Version 2.13.0-44.0.dev

Merge commit '0897b95f3cc2d776c0b6f272cbe1137f3ebd5523' into 'dev'
diff --git a/DEPS b/DEPS
index 990085c..aa76f78 100644
--- a/DEPS
+++ b/DEPS
@@ -102,7 +102,7 @@
 
   "chromedriver_tag": "83.0.4103.39",
   "dartdoc_rev" : "9e61a4f11091aaa8998525a2692b14148dc24ab5",
-  "ffi_rev": "afb6b2c3a15c50e8f12ac15f368c7f1560f2d2f1",
+  "ffi_rev": "f3346299c55669cc0db48afae85b8110088bf8da",
   "fixnum_rev": "16d3890c6dc82ca629659da1934e412292508bba",
   "file_rev": "0e09370f581ab6388d46fda4cdab66638c0171a1",
   "glob_rev": "a62acf590598f458d3198d9f2930c1c9dd4b1379",
diff --git a/pkg/analyzer/lib/src/dart/constant/compute.dart b/pkg/analyzer/lib/src/dart/constant/compute.dart
index e81acbb..b7a2d02 100644
--- a/pkg/analyzer/lib/src/dart/constant/compute.dart
+++ b/pkg/analyzer/lib/src/dart/constant/compute.dart
@@ -77,7 +77,8 @@
   }
 
   ConstantEvaluationEngine _getEvaluationEngine(_ConstantNode node) {
-    return ConstantEvaluationEngine(declaredVariables);
+    return ConstantEvaluationEngine(
+        declaredVariables, experimentStatus.triple_shift);
   }
 
   _ConstantNode _getNode(ConstantEvaluationTarget constant) {
diff --git a/pkg/analyzer/lib/src/dart/constant/constant_verifier.dart b/pkg/analyzer/lib/src/dart/constant/constant_verifier.dart
index 3462422..e64a4ab 100644
--- a/pkg/analyzer/lib/src/dart/constant/constant_verifier.dart
+++ b/pkg/analyzer/lib/src/dart/constant/constant_verifier.dart
@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/dart/analysis/declared_variables.dart';
+import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/token.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
@@ -65,7 +66,8 @@
     this._typeSystem,
     this._typeProvider,
     this.declaredVariables,
-  ) : _evaluationEngine = ConstantEvaluationEngine(declaredVariables);
+  ) : _evaluationEngine = ConstantEvaluationEngine(declaredVariables,
+            _currentLibrary.featureSet.isEnabled(Feature.triple_shift));
 
   bool get _isNonNullableByDefault => _currentLibrary.isNonNullableByDefault;
 
diff --git a/pkg/analyzer/lib/src/dart/constant/evaluation.dart b/pkg/analyzer/lib/src/dart/constant/evaluation.dart
index ce9b3b7..89ce0ba 100644
--- a/pkg/analyzer/lib/src/dart/constant/evaluation.dart
+++ b/pkg/analyzer/lib/src/dart/constant/evaluation.dart
@@ -58,11 +58,15 @@
   /// The set of variables declared on the command line using '-D'.
   final DeclaredVariables _declaredVariables;
 
+  /// Whether the `triple_shift` experiment is enabled.
+  final bool _isTripleShiftExperimentEnabled;
+
   /// Initialize a newly created [ConstantEvaluationEngine].
   ///
   /// [declaredVariables] is the set of variables declared on the command
   /// line using '-D'.
-  ConstantEvaluationEngine(DeclaredVariables declaredVariables)
+  ConstantEvaluationEngine(
+      DeclaredVariables declaredVariables, this._isTripleShiftExperimentEnabled)
       : _declaredVariables = declaredVariables;
 
   /// Check that the arguments to a call to fromEnvironment() are correct. The
@@ -127,7 +131,14 @@
       return false;
     }
     var name = argumentValues[0]?.toStringValue();
-    return name != null && isValidPublicSymbol(name);
+    if (name == null) {
+      return false;
+    }
+    // TODO(srawlins): If the argument is '>>>' but triple-shift is not enabled,
+    // report a different error indicating that the triple-shift experiment
+    // should be enabled, or a minimum SDK version set, when one is declared.
+    return isValidPublicSymbol(name) ||
+        (_isTripleShiftExperimentEnabled && name == '>>>');
   }
 
   /// Compute the constant value associated with the given [constant].
@@ -414,11 +425,11 @@
 
     constructor = followConstantRedirectionChain(constructor);
     InterfaceType definingType = constructor.returnType;
-    ClassElement definingClass = constructor.enclosingElement;
     if (constructor.isFactory) {
       // We couldn't find a non-factory constructor.
       // See if it's because we reached an external const factory constructor
       // that we can emulate.
+      ClassElement definingClass = constructor.enclosingElement;
       if (constructor.name == "fromEnvironment") {
         if (!checkFromEnvironmentArguments(
             library, arguments, argumentValues, namedValues, definingType)) {
@@ -479,8 +490,6 @@
         definingType,
       );
     }
-    var constructorBase = constructor.declaration as ConstructorElementImpl;
-    var initializers = constructorBase.constantInitializers;
 
     var fieldMap = HashMap<String, DartObjectImpl>();
 
@@ -597,6 +606,8 @@
       lexicalEnvironment: parameterMap,
       substitution: Substitution.fromInterfaceType(definingType),
     );
+    var constructorBase = constructor.declaration as ConstructorElementImpl;
+    var initializers = constructorBase.constantInitializers;
     String? superName;
     NodeList<Expression>? superArguments;
     for (var i = 0; i < initializers.length; i++) {
diff --git a/pkg/analyzer/lib/src/dart/constant/value.dart b/pkg/analyzer/lib/src/dart/constant/value.dart
index 0730163..ca4a5a1 100644
--- a/pkg/analyzer/lib/src/dart/constant/value.dart
+++ b/pkg/analyzer/lib/src/dart/constant/value.dart
@@ -1676,8 +1676,8 @@
     return BoolState.from(leftValue | rightValue);
   }
 
-  /// Return the result of invoking the '&gt;&gt;' operator on this object with
-  /// the [rightOperand].
+  /// Return the result of invoking the '&gt;&gt;&gt;' operator on this object
+  /// with the [rightOperand].
   ///
   /// Throws an [EvaluationException] if the operator is not appropriate for an
   /// object of this kind.
diff --git a/pkg/analyzer/lib/src/generated/constant.dart b/pkg/analyzer/lib/src/generated/constant.dart
index 922128a..fecdee1 100644
--- a/pkg/analyzer/lib/src/generated/constant.dart
+++ b/pkg/analyzer/lib/src/generated/constant.dart
@@ -3,6 +3,7 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:analyzer/dart/analysis/declared_variables.dart';
+import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/listener.dart';
@@ -113,6 +114,7 @@
     var result = expression.accept(ConstantVisitor(
         ConstantEvaluationEngine(
           DeclaredVariables(),
+          _library.featureSet.isEnabled(Feature.triple_shift),
         ),
         _library,
         errorReporter));
diff --git a/pkg/analyzer/lib/src/lint/linter.dart b/pkg/analyzer/lib/src/lint/linter.dart
index fd04724..9d8c65f 100644
--- a/pkg/analyzer/lib/src/lint/linter.dart
+++ b/pkg/analyzer/lib/src/lint/linter.dart
@@ -369,7 +369,8 @@
     );
 
     var visitor = ConstantVisitor(
-      ConstantEvaluationEngine(declaredVariables),
+      ConstantEvaluationEngine(
+          declaredVariables, isEnabled(Feature.triple_shift)),
       libraryElement,
       errorReporter,
     );
diff --git a/pkg/analyzer/test/src/dart/constant/evaluation_test.dart b/pkg/analyzer/test/src/dart/constant/evaluation_test.dart
index c835e16..00f46d5 100644
--- a/pkg/analyzer/test/src/dart/constant/evaluation_test.dart
+++ b/pkg/analyzer/test/src/dart/constant/evaluation_test.dart
@@ -2,6 +2,7 @@
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
+import 'package:analyzer/dart/analysis/features.dart';
 import 'package:analyzer/error/error.dart';
 import 'package:analyzer/error/listener.dart';
 import 'package:analyzer/src/dart/analysis/experiments.dart';
@@ -1042,7 +1043,11 @@
   }) {
     var expression = findNode.topVariableDeclarationByName(name).initializer!;
 
-    var source = this.result.unit!.declaredElement!.source;
+    var unit = this.result.unit;
+    if (unit == null) {
+      throw StateError('analysis result unit is null');
+    }
+    var source = unit.declaredElement!.source;
     var errorListener = GatheringErrorListener();
     var errorReporter = ErrorReporter(
       errorListener,
@@ -1054,6 +1059,7 @@
       ConstantVisitor(
         ConstantEvaluationEngine(
           DeclaredVariables.fromMap(declaredVariables),
+          unit.featureSet.isEnabled(Feature.triple_shift),
         ),
         this.result.libraryElement as LibraryElementImpl,
         errorReporter,
diff --git a/pkg/analyzer/test/src/diagnostics/wrong_number_of_parameters_for_operator_test.dart b/pkg/analyzer/test/src/diagnostics/wrong_number_of_parameters_for_operator_test.dart
index 9b90ee6..9ee48c6 100644
--- a/pkg/analyzer/test/src/diagnostics/wrong_number_of_parameters_for_operator_test.dart
+++ b/pkg/analyzer/test/src/diagnostics/wrong_number_of_parameters_for_operator_test.dart
@@ -80,6 +80,8 @@
   test_unaryTilde() async {
     await _check('~', 'a');
     await _check('~', 'a, b');
+    await _check('~', 'a, [b]');
+    await _check('~', 'a, {b}');
   }
 
   Future<void> _check(String name, String parameters) async {
@@ -108,5 +110,7 @@
   Future<void> _checkTooFewAndTooMany(String name) async {
     await _check(name, '');
     await _check(name, 'a, b');
+    await _check(name, 'a, [b]');
+    await _check(name, 'a, {b}');
   }
 }
diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index 614454c..bedea60 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -2726,7 +2726,12 @@
   @override
   void handleAssignmentExpression(Token token) {
     assert(checkState(token, [
-      unionOfKinds(<ValueKind>[ValueKinds.Expression, ValueKinds.Generator]),
+      unionOfKinds(<ValueKind>[
+        ValueKinds.Expression,
+        ValueKinds.Generator,
+        // TODO(johnniwinther): Avoid problem builders here.
+        ValueKinds.ProblemBuilder
+      ]),
       unionOfKinds(<ValueKind>[
         ValueKinds.Expression, ValueKinds.Generator,
         // TODO(johnniwinther): Avoid problem builders here.
diff --git a/pkg/front_end/lib/src/fasta/source/source_library_builder.dart b/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
index 2597332..a68f32c 100644
--- a/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_library_builder.dart
@@ -892,55 +892,69 @@
     assert(checkForMethodVsSetterConflict != null);
 
     scope.forEachLocalSetter((String name, MemberBuilder setter) {
-      Builder member = scope.lookupLocalMember(name, setter: false);
-      if (member == null) {
+      Builder getable = scope.lookupLocalMember(name, setter: false);
+      if (getable == null) {
         // Setter without getter.
         return;
       }
-      MemberBuilderImpl setterBuilder = setter;
-      do {
-        bool conflict = checkForInstanceVsStaticConflict &&
-            member.isDeclarationInstanceMember !=
-                setterBuilder.isDeclarationInstanceMember;
-        if (member is FieldBuilder) {
-          if (member.isAssignable) {
+
+      bool isConflictingSetter = false;
+      Set<Builder> conflictingGetables = {};
+      for (Builder currentGetable = getable;
+          currentGetable != null;
+          currentGetable = currentGetable.next) {
+        if (currentGetable is FieldBuilder) {
+          if (currentGetable.isAssignable) {
             // Setter with writable field.
-            setterBuilder.isConflictingSetter = true;
-            conflict = true;
+            isConflictingSetter = true;
+            conflictingGetables.add(currentGetable);
           }
-        } else if (checkForMethodVsSetterConflict && !member.isGetter) {
+        } else if (checkForMethodVsSetterConflict && !currentGetable.isGetter) {
           // Setter with method.
-          conflict = true;
+          conflictingGetables.add(currentGetable);
+        }
+      }
+      for (MemberBuilderImpl currentSetter = setter;
+          currentSetter != null;
+          currentSetter = currentSetter.next) {
+        bool conflict = conflictingGetables.isNotEmpty;
+        for (Builder currentGetable = getable;
+            currentGetable != null;
+            currentGetable = currentGetable.next) {
+          if (checkForInstanceVsStaticConflict &&
+              currentGetable.isDeclarationInstanceMember !=
+                  currentSetter.isDeclarationInstanceMember) {
+            conflict = true;
+            conflictingGetables.add(currentGetable);
+          }
+        }
+        if (isConflictingSetter) {
+          currentSetter.isConflictingSetter = true;
         }
         if (conflict) {
-          if (setterBuilder.isConflictingSetter) {
+          if (currentSetter.isConflictingSetter) {
             sourceLibraryBuilder.addProblem(
                 templateConflictsWithImplicitSetter.withArguments(name),
-                setterBuilder.charOffset,
+                currentSetter.charOffset,
                 noLength,
-                setterBuilder.fileUri);
-            // TODO(ahe): Context argument to previous message?
-            sourceLibraryBuilder.addProblem(
-                templateConflictsWithSetter.withArguments(name),
-                member.charOffset,
-                noLength,
-                member.fileUri);
+                currentSetter.fileUri);
           } else {
             sourceLibraryBuilder.addProblem(
                 templateConflictsWithMember.withArguments(name),
-                setterBuilder.charOffset,
+                currentSetter.charOffset,
                 noLength,
-                setterBuilder.fileUri);
-            // TODO(ahe): Context argument to previous message?
-            sourceLibraryBuilder.addProblem(
-                templateConflictsWithSetter.withArguments(name),
-                member.charOffset,
-                noLength,
-                member.fileUri);
+                currentSetter.fileUri);
           }
         }
-        setterBuilder = setterBuilder.next;
-      } while (setterBuilder != null);
+      }
+      for (Builder conflictingGetable in conflictingGetables) {
+        // TODO(ahe): Context argument to previous message?
+        sourceLibraryBuilder.addProblem(
+            templateConflictsWithSetter.withArguments(name),
+            conflictingGetable.charOffset,
+            noLength,
+            conflictingGetable.fileUri);
+      }
     });
   }
 
diff --git a/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.outline.expect b/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.outline.expect
index c1106cd..9754b6c 100644
--- a/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.outline.expect
+++ b/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.outline.expect
@@ -241,12 +241,16 @@
 //   set Foo {
 //       ^
 //
+// pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:23:7: Error: Conflicts with the implicit setter of the field 'Foo'.
+//   set Foo => 0;
+//       ^
+//
 // pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:40:10: Error: Conflicts with setter 'Foo'.
 //   int A, Foo, B;
 //          ^
 //
-// pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:23:7: Error: Conflicts with the implicit setter of the field 'Foo'.
-//   set Foo => 0;
+// pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:39:7: Error: Conflicts with setter 'Foo'.
+//   int Foo;
 //       ^
 //
 import self as self;
diff --git a/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.strong.expect b/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.strong.expect
index e9229ec..77778a5 100644
--- a/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.strong.expect
+++ b/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.strong.expect
@@ -241,12 +241,16 @@
 //   set Foo {
 //       ^
 //
+// pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:23:7: Error: Conflicts with the implicit setter of the field 'Foo'.
+//   set Foo => 0;
+//       ^
+//
 // pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:40:10: Error: Conflicts with setter 'Foo'.
 //   int A, Foo, B;
 //          ^
 //
-// pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:23:7: Error: Conflicts with the implicit setter of the field 'Foo'.
-//   set Foo => 0;
+// pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:39:7: Error: Conflicts with setter 'Foo'.
+//   int Foo;
 //       ^
 //
 // pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:5:13: Error: 'initializer' isn't an instance field of this class.
diff --git a/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.strong.transformed.expect b/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.strong.transformed.expect
index e9229ec..77778a5 100644
--- a/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart.strong.transformed.expect
@@ -241,12 +241,16 @@
 //   set Foo {
 //       ^
 //
+// pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:23:7: Error: Conflicts with the implicit setter of the field 'Foo'.
+//   set Foo => 0;
+//       ^
+//
 // pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:40:10: Error: Conflicts with setter 'Foo'.
 //   int A, Foo, B;
 //          ^
 //
-// pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:23:7: Error: Conflicts with the implicit setter of the field 'Foo'.
-//   set Foo => 0;
+// pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:39:7: Error: Conflicts with setter 'Foo'.
+//   int Foo;
 //       ^
 //
 // pkg/front_end/testcases/general/error_recovery/constructor_recovery_bad_name_general.crash_dart:5:13: Error: 'initializer' isn't an instance field of this class.
diff --git a/pkg/front_end/testcases/general_nnbd_opt_out/ffi_sample.dart.weak.transformed.expect b/pkg/front_end/testcases/general_nnbd_opt_out/ffi_sample.dart.weak.transformed.expect
index 8c4ed96..6fa5bec 100644
--- a/pkg/front_end/testcases/general_nnbd_opt_out/ffi_sample.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general_nnbd_opt_out/ffi_sample.dart.weak.transformed.expect
@@ -1,8 +1,3 @@
-//
-// Problems outside component:
-//
-// third_party/pkg/ffi/lib/src/allocation.dart: Info: Support for using non-constant type arguments 'T' in this FFI API is deprecated and will be removed in the next stable version of Dart. Rewrite the code to ensure that type arguments are compile time constants referring to a valid native type.
-//
 library;
 import self as self;
 import "dart:core" as core;
diff --git a/pkg/front_end/testcases/nnbd/ffi_sample.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/ffi_sample.dart.strong.transformed.expect
index e8d0533..e7212d8 100644
--- a/pkg/front_end/testcases/nnbd/ffi_sample.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/ffi_sample.dart.strong.transformed.expect
@@ -1,8 +1,3 @@
-//
-// Problems outside component:
-//
-// third_party/pkg/ffi/lib/src/allocation.dart: Info: Support for using non-constant type arguments 'T' in this FFI API is deprecated and will be removed in the next stable version of Dart. Rewrite the code to ensure that type arguments are compile time constants referring to a valid native type.
-//
 library /*isNonNullableByDefault*/;
 import self as self;
 import "dart:core" as core;
diff --git a/pkg/front_end/testcases/nnbd/ffi_sample.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/ffi_sample.dart.weak.transformed.expect
index e8d0533..e7212d8 100644
--- a/pkg/front_end/testcases/nnbd/ffi_sample.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/ffi_sample.dart.weak.transformed.expect
@@ -1,8 +1,3 @@
-//
-// Problems outside component:
-//
-// third_party/pkg/ffi/lib/src/allocation.dart: Info: Support for using non-constant type arguments 'T' in this FFI API is deprecated and will be removed in the next stable version of Dart. Rewrite the code to ensure that type arguments are compile time constants referring to a valid native type.
-//
 library /*isNonNullableByDefault*/;
 import self as self;
 import "dart:core" as core;
diff --git a/pkg/front_end/testcases/nnbd/field_vs_setter.dart b/pkg/front_end/testcases/nnbd/field_vs_setter.dart
index 17d64ba..e4dbee8 100644
--- a/pkg/front_end/testcases/nnbd/field_vs_setter.dart
+++ b/pkg/front_end/testcases/nnbd/field_vs_setter.dart
@@ -9,6 +9,14 @@
 void set topLevelFieldAndDuplicateSetter(int? value) {}
 void set topLevelFieldAndDuplicateSetter(int? value) {}
 
+int? duplicateTopLevelFieldAndSetter1;
+final int? duplicateTopLevelFieldAndSetter1 = null;
+void set duplicateTopLevelFieldAndSetter1(int? value) {}
+
+final int? duplicateTopLevelFieldAndSetter2 = null;
+int? duplicateTopLevelFieldAndSetter2;
+void set duplicateTopLevelFieldAndSetter2(int? value) {}
+
 late final int? topLevelLateFinalFieldAndSetter;
 void set topLevelLateFinalFieldAndSetter(int? value) {}
 
@@ -24,6 +32,14 @@
   void set instanceFieldAndDuplicateSetter(int? value) {}
   void set instanceFieldAndDuplicateSetter(int? value) {}
 
+  int? duplicateInstanceFieldAndSetter1;
+  final int? duplicateInstanceFieldAndSetter1 = null;
+  void set duplicateInstanceFieldAndSetter1(int? value) {}
+
+  final int? duplicateInstanceFieldAndSetter2 = null;
+  int? duplicateInstanceFieldAndSetter2;
+  void set duplicateInstanceFieldAndSetter2(int? value) {}
+
   late final int? instanceLateFinalFieldAndSetter;
   void set instanceLateFinalFieldAndSetter(int? value) {}
 
@@ -38,6 +54,14 @@
   static void set staticFieldAndDuplicateSetter(int? value) {}
   static void set staticFieldAndDuplicateSetter(int? value) {}
 
+  static int? duplicateStaticFieldAndSetter1;
+  static final int? duplicateStaticFieldAndSetter1 = null;
+  static void set duplicateStaticFieldAndSetter1(int? value) {}
+
+  static final int? duplicateStaticFieldAndSetter2 = null;
+  static int? duplicateStaticFieldAndSetter2;
+  static void set duplicateStaticFieldAndSetter2(int? value) {}
+
   static late final int? staticLateFinalFieldAndSetter;
   static void set staticLateFinalFieldAndSetter(int? value) {}
 
@@ -58,6 +82,22 @@
   int? instanceFieldAndStaticDuplicateSetter;
   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+
+  int? duplicateInstanceFieldAndStaticSetter1;
+  final int? duplicateInstanceFieldAndStaticSetter1 = null;
+  static void set duplicateInstanceFieldAndStaticSetter1(int? value) {}
+
+  final int? duplicateInstanceFieldAndStaticSetter2 = null;
+  int? duplicateInstanceFieldAndStaticSetter2;
+  static void set duplicateInstanceFieldAndStaticSetter2(int? value) {}
+
+  static int? duplicateStaticFieldAndInstanceSetter1;
+  static final int? duplicateStaticFieldAndInstanceSetter1 = null;
+  void set duplicateStaticFieldAndInstanceSetter1(int? value) {}
+
+  static final int? duplicateStaticFieldAndInstanceSetter2 = null;
+  static int? duplicateStaticFieldAndInstanceSetter2;
+  void set duplicateStaticFieldAndInstanceSetter2(int? value) {}
 }
 
 extension Extension on int? {
@@ -68,6 +108,14 @@
   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 
+  int? duplicateExtensionInstanceFieldAndSetter1;
+  final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+  void set duplicateExtensionInstanceFieldAndSetter1(int? value) {}
+
+  final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+  int? duplicateExtensionInstanceFieldAndSetter2;
+  void set duplicateExtensionInstanceFieldAndSetter2(int? value) {}
+
   static int? extensionStaticFieldAndSetter;
   static void set extensionStaticFieldAndSetter(int? value) {}
 
@@ -75,6 +123,14 @@
   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 
+  static int? duplicateExtensionStaticFieldAndSetter1;
+  static final int? duplicateExtensionStaticFieldAndSetter1 = null;
+  static void set duplicateExtensionStaticFieldAndSetter1(int? value) {}
+
+  static final int? duplicateExtensionStaticFieldAndSetter2 = null;
+  static int? duplicateExtensionStaticFieldAndSetter2;
+  static void set duplicateExtensionStaticFieldAndSetter2(int? value) {}
+
   static late final int? extensionStaticLateFinalFieldAndSetter;
   static void set extensionStaticLateFinalFieldAndSetter(int? value) {}
 
@@ -95,6 +151,22 @@
   int? extensionInstanceFieldAndStaticDuplicateSetter;
   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+
+  int? duplicateExtensionInstanceFieldAndStaticSetter1;
+  final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+  static void set duplicateExtensionInstanceFieldAndStaticSetter1(int? value) {}
+
+  final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+  int? duplicateExtensionInstanceFieldAndStaticSetter2;
+  static void set duplicateExtensionInstanceFieldAndStaticSetter2(int? value) {}
+
+  static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+  static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+  void set duplicateExtensionStaticFieldAndInstanceSetter1(int? value) {}
+
+  static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+  static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+  void set duplicateExtensionStaticFieldAndInstanceSetter2(int? value) {}
 }
 
 test() {
@@ -103,6 +175,8 @@
   topLevelLateFinalFieldAndSetter = topLevelLateFinalFieldAndSetter;
   topLevelLateFinalFieldAndDuplicateSetter =
       topLevelLateFinalFieldAndDuplicateSetter;
+  duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+  duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
 
   var c = new Class();
 
@@ -111,12 +185,18 @@
   c.instanceLateFinalFieldAndSetter = c.instanceLateFinalFieldAndSetter;
   c.instanceLateFinalFieldAndDuplicateSetter =
       c.instanceLateFinalFieldAndDuplicateSetter;
+  c.duplicateInstanceFieldAndStaticSetter1 =
+      c.duplicateInstanceFieldAndStaticSetter1;
+  c.duplicateInstanceFieldAndStaticSetter2 =
+      c.duplicateInstanceFieldAndStaticSetter2;
 
   Class.staticFieldAndSetter = Class.staticFieldAndSetter;
   Class.staticFieldAndDuplicateSetter = Class.staticFieldAndDuplicateSetter;
   Class.staticLateFinalFieldAndSetter = Class.staticLateFinalFieldAndSetter;
   Class.staticLateFinalFieldAndDuplicateSetter =
       Class.staticLateFinalFieldAndDuplicateSetter;
+  Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+  Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
 
   c.staticFieldAndInstanceSetter = Class.staticFieldAndInstanceSetter;
   Class.staticFieldAndInstanceSetter = Class.staticFieldAndInstanceSetter;
@@ -134,10 +214,30 @@
   c.instanceFieldAndStaticDuplicateSetter =
       c.instanceFieldAndStaticDuplicateSetter;
 
+  c.duplicateStaticFieldAndInstanceSetter1 =
+      Class.duplicateStaticFieldAndInstanceSetter1;
+  Class.duplicateStaticFieldAndInstanceSetter1 =
+      Class.duplicateStaticFieldAndInstanceSetter1;
+
+  c.duplicateStaticFieldAndInstanceSetter2 =
+      Class.duplicateStaticFieldAndInstanceSetter2;
+  Class.duplicateStaticFieldAndInstanceSetter2 =
+      Class.duplicateStaticFieldAndInstanceSetter2;
+
+  Class.duplicateInstanceFieldAndStaticSetter1 =
+      0.duplicateInstanceFieldAndStaticSetter1;
+  Class.duplicateInstanceFieldAndStaticSetter2 =
+      0.duplicateInstanceFieldAndStaticSetter2;
+
   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
   0.extensionInstanceFieldAndDuplicateSetter =
       0.extensionInstanceFieldAndDuplicateSetter;
 
+  0.duplicateExtensionInstanceFieldAndSetter1 =
+      0.duplicateExtensionInstanceFieldAndSetter1;
+  0.duplicateExtensionInstanceFieldAndSetter2 =
+      0.duplicateExtensionInstanceFieldAndSetter2;
+
   Extension.extensionStaticFieldAndSetter =
       Extension.extensionStaticFieldAndSetter;
 
@@ -149,6 +249,10 @@
 
   Extension.extensionStaticLateFinalFieldAndDuplicateSetter =
       Extension.extensionStaticLateFinalFieldAndDuplicateSetter;
+  Extension.duplicateExtensionStaticFieldAndSetter1 =
+      Extension.duplicateExtensionStaticFieldAndSetter1;
+  Extension.duplicateExtensionStaticFieldAndSetter2 =
+      Extension.duplicateExtensionStaticFieldAndSetter2;
 
   0.extensionStaticFieldAndInstanceSetter =
       Extension.extensionStaticFieldAndInstanceSetter;
@@ -169,6 +273,26 @@
       0.extensionInstanceFieldAndStaticDuplicateSetter;
   0.extensionInstanceFieldAndStaticDuplicateSetter =
       0.extensionInstanceFieldAndStaticDuplicateSetter;
+
+  Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+      0.duplicateExtensionInstanceFieldAndStaticSetter1;
+  0.duplicateExtensionInstanceFieldAndStaticSetter1 =
+      0.duplicateExtensionInstanceFieldAndStaticSetter1;
+
+  Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+      0.duplicateExtensionInstanceFieldAndStaticSetter2;
+  0.duplicateExtensionInstanceFieldAndStaticSetter2 =
+      0.duplicateExtensionInstanceFieldAndStaticSetter2;
+
+  Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+      Extension.duplicateExtensionStaticFieldAndInstanceSetter1;
+  0.duplicateExtensionStaticFieldAndInstanceSetter1 =
+      Extension.duplicateExtensionStaticFieldAndInstanceSetter1;
+
+  Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+      Extension.duplicateExtensionStaticFieldAndInstanceSetter2;
+  0.duplicateExtensionStaticFieldAndInstanceSetter2 =
+      Extension.duplicateExtensionStaticFieldAndInstanceSetter2;
 }
 
 main() {}
diff --git a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.outline.expect b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.outline.expect
index 3731cb56..87c41fa 100644
--- a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.outline.expect
+++ b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.outline.expect
@@ -9,110 +9,276 @@
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:10: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:13:12: Error: 'duplicateTopLevelFieldAndSetter1' is already declared in this scope.
+// final int? duplicateTopLevelFieldAndSetter1 = null;
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:6: Context: Previous declaration of 'duplicateTopLevelFieldAndSetter1'.
+// int? duplicateTopLevelFieldAndSetter1;
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:6: Error: 'duplicateTopLevelFieldAndSetter2' is already declared in this scope.
+// int? duplicateTopLevelFieldAndSetter2;
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:12: Context: Previous declaration of 'duplicateTopLevelFieldAndSetter2'.
+// final int? duplicateTopLevelFieldAndSetter2 = null;
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:10: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:10: Context: Previous declaration of 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:10: Context: Previous declaration of 'topLevelLateFinalFieldAndDuplicateSetter'.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:12: Error: 'instanceFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:33:12: Error: 'instanceFieldAndDuplicateSetter' is already declared in this scope.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:12: Context: Previous declaration of 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Context: Previous declaration of 'instanceFieldAndDuplicateSetter'.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: 'instanceLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:36:14: Error: 'duplicateInstanceFieldAndSetter1' is already declared in this scope.
+//   final int? duplicateInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:8: Context: Previous declaration of 'duplicateInstanceFieldAndSetter1'.
+//   int? duplicateInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:40:8: Error: 'duplicateInstanceFieldAndSetter2' is already declared in this scope.
+//   int? duplicateInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:14: Context: Previous declaration of 'duplicateInstanceFieldAndSetter2'.
+//   final int? duplicateInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:12: Error: 'instanceLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:12: Context: Previous declaration of 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:47:12: Context: Previous declaration of 'instanceLateFinalFieldAndDuplicateSetter'.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:19: Error: 'staticFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:19: Error: 'staticFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:38:19: Context: Previous declaration of 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:54:19: Context: Previous declaration of 'staticFieldAndDuplicateSetter'.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: 'staticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:58:21: Error: 'duplicateStaticFieldAndSetter1' is already declared in this scope.
+//   static final int? duplicateStaticFieldAndSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:57:15: Context: Previous declaration of 'duplicateStaticFieldAndSetter1'.
+//   static int? duplicateStaticFieldAndSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:62:15: Error: 'duplicateStaticFieldAndSetter2' is already declared in this scope.
+//   static int? duplicateStaticFieldAndSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:61:21: Context: Previous declaration of 'duplicateStaticFieldAndSetter2'.
+//   static final int? duplicateStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:70:19: Error: 'staticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:45:19: Context: Previous declaration of 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:19: Context: Previous declaration of 'staticLateFinalFieldAndDuplicateSetter'.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:12: Error: 'staticFieldAndInstanceDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:77:12: Error: 'staticFieldAndInstanceDuplicateSetter' is already declared in this scope.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:52:12: Context: Previous declaration of 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:12: Context: Previous declaration of 'staticFieldAndInstanceDuplicateSetter'.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:60:19: Error: 'instanceFieldAndStaticDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:84:19: Error: 'instanceFieldAndStaticDuplicateSetter' is already declared in this scope.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Context: Previous declaration of 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Context: Previous declaration of 'instanceFieldAndStaticDuplicateSetter'.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:64:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:87:14: Error: 'duplicateInstanceFieldAndStaticSetter1' is already declared in this scope.
+//   final int? duplicateInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:8: Context: Previous declaration of 'duplicateInstanceFieldAndStaticSetter1'.
+//   int? duplicateInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:91:8: Error: 'duplicateInstanceFieldAndStaticSetter2' is already declared in this scope.
+//   int? duplicateInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:14: Context: Previous declaration of 'duplicateInstanceFieldAndStaticSetter2'.
+//   final int? duplicateInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:21: Error: 'duplicateStaticFieldAndInstanceSetter1' is already declared in this scope.
+//   static final int? duplicateStaticFieldAndInstanceSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:94:15: Context: Previous declaration of 'duplicateStaticFieldAndInstanceSetter1'.
+//   static int? duplicateStaticFieldAndInstanceSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:99:15: Error: 'duplicateStaticFieldAndInstanceSetter2' is already declared in this scope.
+//   static int? duplicateStaticFieldAndInstanceSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:98:21: Context: Previous declaration of 'duplicateStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:104:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:67:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:107:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndDuplicateSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:12: Error: 'extensionInstanceFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:109:12: Error: 'extensionInstanceFieldAndDuplicateSetter' is already declared in this scope.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:12: Context: Previous declaration of 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:108:12: Context: Previous declaration of 'extensionInstanceFieldAndDuplicateSetter'.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:19: Error: 'extensionStaticFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:112:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:112:14: Error: 'duplicateExtensionInstanceFieldAndSetter1' is already declared in this scope.
+//   final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndSetter1'.
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:115:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: 'duplicateExtensionInstanceFieldAndSetter2' is already declared in this scope.
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:115:14: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:19: Error: 'extensionStaticFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:19: Context: Previous declaration of 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:123:19: Context: Previous declaration of 'extensionStaticFieldAndDuplicateSetter'.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: 'extensionStaticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:127:21: Error: 'duplicateExtensionStaticFieldAndSetter1' is already declared in this scope.
+//   static final int? duplicateExtensionStaticFieldAndSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:126:15: Context: Previous declaration of 'duplicateExtensionStaticFieldAndSetter1'.
+//   static int? duplicateExtensionStaticFieldAndSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:131:15: Error: 'duplicateExtensionStaticFieldAndSetter2' is already declared in this scope.
+//   static int? duplicateExtensionStaticFieldAndSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:130:21: Context: Previous declaration of 'duplicateExtensionStaticFieldAndSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:19: Error: 'extensionStaticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:19: Context: Previous declaration of 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:19: Context: Previous declaration of 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:12: Error: 'extensionStaticFieldAndInstanceDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:146:12: Error: 'extensionStaticFieldAndInstanceDuplicateSetter' is already declared in this scope.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:89:12: Context: Previous declaration of 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:145:12: Context: Previous declaration of 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:148:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndStaticSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:151:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndStaticDuplicateSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:97:19: Error: 'extensionInstanceFieldAndStaticDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:19: Error: 'extensionInstanceFieldAndStaticDuplicateSetter' is already declared in this scope.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:19: Context: Previous declaration of 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:152:19: Context: Previous declaration of 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: 'duplicateExtensionInstanceFieldAndStaticSetter1' is already declared in this scope.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: 'duplicateExtensionInstanceFieldAndStaticSetter2' is already declared in this scope.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:164:21: Error: 'duplicateExtensionStaticFieldAndInstanceSetter1' is already declared in this scope.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:15: Context: Previous declaration of 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:15: Error: 'duplicateExtensionStaticFieldAndInstanceSetter2' is already declared in this scope.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:167:21: Context: Previous declaration of 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart: Error: 'topLevelFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 //
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
@@ -129,299 +295,485 @@
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:8:6: Error: Conflicts with setter 'topLevelFieldAndDuplicateSetter'.
-// int? topLevelFieldAndDuplicateSetter;
-//      ^
-//
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart:9:10: Error: Conflicts with the implicit setter of the field 'topLevelFieldAndDuplicateSetter'.
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:13:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:8:6: Error: Conflicts with setter 'topLevelFieldAndDuplicateSetter'.
+// int? topLevelFieldAndDuplicateSetter;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:14:10: Error: Conflicts with the implicit setter of the field 'duplicateTopLevelFieldAndSetter1'.
+// void set duplicateTopLevelFieldAndSetter1(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:6: Error: Conflicts with setter 'duplicateTopLevelFieldAndSetter1'.
+// int? duplicateTopLevelFieldAndSetter1;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:18:10: Error: Conflicts with the implicit setter of the field 'duplicateTopLevelFieldAndSetter2'.
+// void set duplicateTopLevelFieldAndSetter2(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:6: Error: Conflicts with setter 'duplicateTopLevelFieldAndSetter2'.
+// int? duplicateTopLevelFieldAndSetter2;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:21:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndSetter'.
 // void set topLevelLateFinalFieldAndSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:20:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndSetter'.
 // late final int? topLevelLateFinalFieldAndSetter;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:15:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
+// void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:23:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndDuplicateSetter'.
 // late final int? topLevelLateFinalFieldAndDuplicateSetter;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
-// void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
-//          ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:21:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:29:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndSetter'.
 //   void set instanceFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:20:8: Error: Conflicts with setter 'instanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:28:8: Error: Conflicts with setter 'instanceFieldAndSetter'.
 //   int? instanceFieldAndSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:33:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:23:8: Error: Conflicts with setter 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
+//   void set instanceFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:8: Error: Conflicts with setter 'instanceFieldAndDuplicateSetter'.
 //   int? instanceFieldAndDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
-//   void set instanceFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:37:12: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndSetter1'.
+//   void set duplicateInstanceFieldAndSetter1(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:28:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:8: Error: Conflicts with setter 'duplicateInstanceFieldAndSetter1'.
+//   int? duplicateInstanceFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:41:12: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndSetter2'.
+//   void set duplicateInstanceFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:40:8: Error: Conflicts with setter 'duplicateInstanceFieldAndSetter2'.
+//   int? duplicateInstanceFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:44:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndSetter'.
 //   void set instanceLateFinalFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:27:19: Error: Conflicts with setter 'instanceLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:43:19: Error: Conflicts with setter 'instanceLateFinalFieldAndSetter'.
 //   late final int? instanceLateFinalFieldAndSetter;
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:30:19: Error: Conflicts with setter 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:47:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
+//   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: Conflicts with setter 'instanceLateFinalFieldAndDuplicateSetter'.
 //   late final int? instanceLateFinalFieldAndDuplicateSetter;
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
-//   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:51:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndSetter'.
 //   static void set staticFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:34:15: Error: Conflicts with setter 'staticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:50:15: Error: Conflicts with setter 'staticFieldAndSetter'.
 //   static int? staticFieldAndSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:37:15: Error: Conflicts with setter 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:54:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
+//   static void set staticFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:15: Error: Conflicts with setter 'staticFieldAndDuplicateSetter'.
 //   static int? staticFieldAndDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:38:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
-//   static void set staticFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndSetter1'.
+//   static void set duplicateStaticFieldAndSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:42:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:57:15: Error: Conflicts with setter 'duplicateStaticFieldAndSetter1'.
+//   static int? duplicateStaticFieldAndSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:63:19: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndSetter2'.
+//   static void set duplicateStaticFieldAndSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:62:15: Error: Conflicts with setter 'duplicateStaticFieldAndSetter2'.
+//   static int? duplicateStaticFieldAndSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:66:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndSetter'.
 //   static void set staticLateFinalFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:41:26: Error: Conflicts with setter 'staticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:65:26: Error: Conflicts with setter 'staticLateFinalFieldAndSetter'.
 //   static late final int? staticLateFinalFieldAndSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:70:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:44:26: Error: Conflicts with setter 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
+//   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:26: Error: Conflicts with setter 'staticLateFinalFieldAndDuplicateSetter'.
 //   static late final int? staticLateFinalFieldAndDuplicateSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:45:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
-//   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
-//                   ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:49:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:73:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceSetter'.
 //   void set staticFieldAndInstanceSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:15: Error: Conflicts with setter 'staticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:72:15: Error: Conflicts with setter 'staticFieldAndInstanceSetter'.
 //   static int? staticFieldAndInstanceSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:77:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:51:15: Error: Conflicts with setter 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
+//   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:15: Error: Conflicts with setter 'staticFieldAndInstanceDuplicateSetter'.
 //   static int? staticFieldAndInstanceDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:52:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
-//   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:56:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:80:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticSetter'.
 //   static void set instanceFieldAndStaticSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:8: Error: Conflicts with setter 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:79:8: Error: Conflicts with setter 'instanceFieldAndStaticSetter'.
 //   int? instanceFieldAndStaticSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:60:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:84:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:58:8: Error: Conflicts with setter 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
+//   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:8: Error: Conflicts with setter 'instanceFieldAndStaticDuplicateSetter'.
 //   int? instanceFieldAndStaticDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
-//   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:88:19: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndStaticSetter1'.
+//   static void set duplicateInstanceFieldAndStaticSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:65:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:8: Error: Conflicts with setter 'duplicateInstanceFieldAndStaticSetter1'.
+//   int? duplicateInstanceFieldAndStaticSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:19: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndStaticSetter2'.
+//   static void set duplicateInstanceFieldAndStaticSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:91:8: Error: Conflicts with setter 'duplicateInstanceFieldAndStaticSetter2'.
+//   int? duplicateInstanceFieldAndStaticSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:12: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndInstanceSetter1'.
+//   void set duplicateStaticFieldAndInstanceSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:94:15: Error: Conflicts with setter 'duplicateStaticFieldAndInstanceSetter1'.
+//   static int? duplicateStaticFieldAndInstanceSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:100:12: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndInstanceSetter2'.
+//   void set duplicateStaticFieldAndInstanceSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:99:15: Error: Conflicts with setter 'duplicateStaticFieldAndInstanceSetter2'.
+//   static int? duplicateStaticFieldAndInstanceSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:105:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndSetter'.
 //   void set extensionInstanceFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:64:8: Error: Conflicts with setter 'extensionInstanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:104:8: Error: Conflicts with setter 'extensionInstanceFieldAndSetter'.
 //   int? extensionInstanceFieldAndSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:109:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:67:8: Error: Conflicts with setter 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:108:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
+//   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:107:8: Error: Conflicts with setter 'extensionInstanceFieldAndDuplicateSetter'.
 //   int? extensionInstanceFieldAndDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
-//   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:113:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndSetter1'.
+//   void set duplicateExtensionInstanceFieldAndSetter1(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:72:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndSetter1'.
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:117:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndSetter2'.
+//   void set duplicateExtensionInstanceFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndSetter2'.
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:120:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndSetter'.
 //   static void set extensionStaticFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:71:15: Error: Conflicts with setter 'extensionStaticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:119:15: Error: Conflicts with setter 'extensionStaticFieldAndSetter'.
 //   static int? extensionStaticFieldAndSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:74:15: Error: Conflicts with setter 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:123:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
+//   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:122:15: Error: Conflicts with setter 'extensionStaticFieldAndDuplicateSetter'.
 //   static int? extensionStaticFieldAndDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
-//   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:128:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndSetter1'.
+//   static void set duplicateExtensionStaticFieldAndSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:79:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:126:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndSetter1'.
+//   static int? duplicateExtensionStaticFieldAndSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndSetter2'.
+//   static void set duplicateExtensionStaticFieldAndSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:131:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndSetter2'.
+//   static int? duplicateExtensionStaticFieldAndSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:135:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndSetter'.
 //   static void set extensionStaticLateFinalFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:78:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:134:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndSetter'.
 //   static late final int? extensionStaticLateFinalFieldAndSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:81:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+//   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static late final int? extensionStaticLateFinalFieldAndDuplicateSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
-//   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
-//                   ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:142:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceSetter'.
 //   void set extensionStaticFieldAndInstanceSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:85:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:141:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceSetter'.
 //   static int? extensionStaticFieldAndInstanceSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:146:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:88:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:145:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
+//   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:144:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   static int? extensionStaticFieldAndInstanceDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:89:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
-//   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:93:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:149:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticSetter'.
 //   static void set extensionInstanceFieldAndStaticSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:148:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticSetter'.
 //   int? extensionInstanceFieldAndStaticSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:97:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:152:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
+//   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:151:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   int? extensionInstanceFieldAndStaticDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
-//   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:157:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   static void set duplicateExtensionInstanceFieldAndStaticSetter1(int? value) {}
 //                   ^
 //
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:161:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   static void set duplicateExtensionInstanceFieldAndStaticSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   void set duplicateExtensionStaticFieldAndInstanceSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:164:21: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+//                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:169:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   void set duplicateExtensionStaticFieldAndInstanceSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:167:21: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+//                     ^
+//
 import self as self;
 import "dart:core" as core;
 
 class Class extends core::Object {
   field core::int? instanceFieldAndSetter;
   field core::int? instanceFieldAndDuplicateSetter;
+  field core::int? duplicateInstanceFieldAndSetter1;
+  final field core::int? duplicateInstanceFieldAndSetter2;
   late final [setter] field core::int? instanceLateFinalFieldAndSetter;
   late final [setter] field core::int? instanceLateFinalFieldAndDuplicateSetter;
   static field core::int? staticFieldAndSetter;
   static field core::int? staticFieldAndDuplicateSetter;
+  static field core::int? duplicateStaticFieldAndSetter1;
+  static final field core::int? duplicateStaticFieldAndSetter2;
   late static final [setter] field core::int? staticLateFinalFieldAndSetter;
   late static final [setter] field core::int? staticLateFinalFieldAndDuplicateSetter;
   static field core::int? staticFieldAndInstanceSetter;
   static field core::int? staticFieldAndInstanceDuplicateSetter;
   field core::int? instanceFieldAndStaticSetter;
   field core::int? instanceFieldAndStaticDuplicateSetter;
+  field core::int? duplicateInstanceFieldAndStaticSetter1;
+  final field core::int? duplicateInstanceFieldAndStaticSetter2;
+  static field core::int? duplicateStaticFieldAndInstanceSetter1;
+  static final field core::int? duplicateStaticFieldAndInstanceSetter2;
   synthetic constructor •() → self::Class
     ;
 }
 extension Extension on core::int? {
   field extensionInstanceFieldAndSetter = self::Extension|extensionInstanceFieldAndSetter;
   field extensionInstanceFieldAndDuplicateSetter = self::Extension|extensionInstanceFieldAndDuplicateSetter;
+  field duplicateExtensionInstanceFieldAndSetter1 = self::Extension|duplicateExtensionInstanceFieldAndSetter1;
+  field duplicateExtensionInstanceFieldAndSetter2 = self::Extension|duplicateExtensionInstanceFieldAndSetter2;
   static field extensionStaticFieldAndSetter = self::Extension|extensionStaticFieldAndSetter;
   static field extensionStaticFieldAndDuplicateSetter = self::Extension|extensionStaticFieldAndDuplicateSetter;
+  static field duplicateExtensionStaticFieldAndSetter1 = self::Extension|duplicateExtensionStaticFieldAndSetter1;
+  static field duplicateExtensionStaticFieldAndSetter2 = self::Extension|duplicateExtensionStaticFieldAndSetter2;
   static field extensionStaticLateFinalFieldAndSetter = self::Extension|extensionStaticLateFinalFieldAndSetter;
   static field extensionStaticLateFinalFieldAndDuplicateSetter = self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
   static field extensionStaticFieldAndInstanceSetter = self::Extension|extensionStaticFieldAndInstanceSetter;
   static field extensionStaticFieldAndInstanceDuplicateSetter = self::Extension|extensionStaticFieldAndInstanceDuplicateSetter;
   field extensionInstanceFieldAndStaticSetter = self::Extension|extensionInstanceFieldAndStaticSetter;
   field extensionInstanceFieldAndStaticDuplicateSetter = self::Extension|extensionInstanceFieldAndStaticDuplicateSetter;
+  field duplicateExtensionInstanceFieldAndStaticSetter1 = self::Extension|duplicateExtensionInstanceFieldAndStaticSetter1;
+  field duplicateExtensionInstanceFieldAndStaticSetter2 = self::Extension|duplicateExtensionInstanceFieldAndStaticSetter2;
+  static field duplicateExtensionStaticFieldAndInstanceSetter1 = self::Extension|duplicateExtensionStaticFieldAndInstanceSetter1;
+  static field duplicateExtensionStaticFieldAndInstanceSetter2 = self::Extension|duplicateExtensionStaticFieldAndInstanceSetter2;
 }
 static field core::int? topLevelFieldAndSetter;
 static field core::int? topLevelFieldAndDuplicateSetter;
+static field core::int? duplicateTopLevelFieldAndSetter1;
+static final field core::int? duplicateTopLevelFieldAndSetter2;
 late static final [setter] field core::int? topLevelLateFinalFieldAndSetter;
 late static final [setter] field core::int? topLevelLateFinalFieldAndDuplicateSetter;
 static field core::int? Extension|extensionInstanceFieldAndSetter;
 static field core::int? Extension|extensionInstanceFieldAndDuplicateSetter;
+static field core::int? Extension|duplicateExtensionInstanceFieldAndSetter1;
+static final field core::int? Extension|duplicateExtensionInstanceFieldAndSetter2;
 static field core::int? Extension|extensionStaticFieldAndSetter;
 static field core::int? Extension|extensionStaticFieldAndDuplicateSetter;
+static field core::int? Extension|duplicateExtensionStaticFieldAndSetter1;
+static final field core::int? Extension|duplicateExtensionStaticFieldAndSetter2;
 late static final [setter] field core::int? Extension|extensionStaticLateFinalFieldAndSetter;
 late static final [setter] field core::int? Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
 static field core::int? Extension|extensionStaticFieldAndInstanceSetter;
 static field core::int? Extension|extensionStaticFieldAndInstanceDuplicateSetter;
 static field core::int? Extension|extensionInstanceFieldAndStaticSetter;
 static field core::int? Extension|extensionInstanceFieldAndStaticDuplicateSetter;
+static field core::int? Extension|duplicateExtensionInstanceFieldAndStaticSetter1;
+static final field core::int? Extension|duplicateExtensionInstanceFieldAndStaticSetter2;
+static field core::int? Extension|duplicateExtensionStaticFieldAndInstanceSetter1;
+static final field core::int? Extension|duplicateExtensionStaticFieldAndInstanceSetter2;
 static const field dynamic _exports# = "{\"topLevelFieldAndDuplicateSetter\":\"'topLevelFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.\",\"topLevelLateFinalFieldAndDuplicateSetter\":\"'topLevelLateFinalFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.\"}" /*isLegacy, from null */;
 static method test() → dynamic
   ;
diff --git a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.strong.expect b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.strong.expect
index f523434..4827498 100644
--- a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.strong.expect
@@ -9,110 +9,276 @@
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:10: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:13:12: Error: 'duplicateTopLevelFieldAndSetter1' is already declared in this scope.
+// final int? duplicateTopLevelFieldAndSetter1 = null;
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:6: Context: Previous declaration of 'duplicateTopLevelFieldAndSetter1'.
+// int? duplicateTopLevelFieldAndSetter1;
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:6: Error: 'duplicateTopLevelFieldAndSetter2' is already declared in this scope.
+// int? duplicateTopLevelFieldAndSetter2;
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:12: Context: Previous declaration of 'duplicateTopLevelFieldAndSetter2'.
+// final int? duplicateTopLevelFieldAndSetter2 = null;
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:10: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:10: Context: Previous declaration of 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:10: Context: Previous declaration of 'topLevelLateFinalFieldAndDuplicateSetter'.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:12: Error: 'instanceFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:33:12: Error: 'instanceFieldAndDuplicateSetter' is already declared in this scope.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:12: Context: Previous declaration of 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Context: Previous declaration of 'instanceFieldAndDuplicateSetter'.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: 'instanceLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:36:14: Error: 'duplicateInstanceFieldAndSetter1' is already declared in this scope.
+//   final int? duplicateInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:8: Context: Previous declaration of 'duplicateInstanceFieldAndSetter1'.
+//   int? duplicateInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:40:8: Error: 'duplicateInstanceFieldAndSetter2' is already declared in this scope.
+//   int? duplicateInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:14: Context: Previous declaration of 'duplicateInstanceFieldAndSetter2'.
+//   final int? duplicateInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:12: Error: 'instanceLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:12: Context: Previous declaration of 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:47:12: Context: Previous declaration of 'instanceLateFinalFieldAndDuplicateSetter'.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:19: Error: 'staticFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:19: Error: 'staticFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:38:19: Context: Previous declaration of 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:54:19: Context: Previous declaration of 'staticFieldAndDuplicateSetter'.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: 'staticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:58:21: Error: 'duplicateStaticFieldAndSetter1' is already declared in this scope.
+//   static final int? duplicateStaticFieldAndSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:57:15: Context: Previous declaration of 'duplicateStaticFieldAndSetter1'.
+//   static int? duplicateStaticFieldAndSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:62:15: Error: 'duplicateStaticFieldAndSetter2' is already declared in this scope.
+//   static int? duplicateStaticFieldAndSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:61:21: Context: Previous declaration of 'duplicateStaticFieldAndSetter2'.
+//   static final int? duplicateStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:70:19: Error: 'staticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:45:19: Context: Previous declaration of 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:19: Context: Previous declaration of 'staticLateFinalFieldAndDuplicateSetter'.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:12: Error: 'staticFieldAndInstanceDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:77:12: Error: 'staticFieldAndInstanceDuplicateSetter' is already declared in this scope.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:52:12: Context: Previous declaration of 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:12: Context: Previous declaration of 'staticFieldAndInstanceDuplicateSetter'.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:60:19: Error: 'instanceFieldAndStaticDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:84:19: Error: 'instanceFieldAndStaticDuplicateSetter' is already declared in this scope.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Context: Previous declaration of 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Context: Previous declaration of 'instanceFieldAndStaticDuplicateSetter'.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:64:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:87:14: Error: 'duplicateInstanceFieldAndStaticSetter1' is already declared in this scope.
+//   final int? duplicateInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:8: Context: Previous declaration of 'duplicateInstanceFieldAndStaticSetter1'.
+//   int? duplicateInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:91:8: Error: 'duplicateInstanceFieldAndStaticSetter2' is already declared in this scope.
+//   int? duplicateInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:14: Context: Previous declaration of 'duplicateInstanceFieldAndStaticSetter2'.
+//   final int? duplicateInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:21: Error: 'duplicateStaticFieldAndInstanceSetter1' is already declared in this scope.
+//   static final int? duplicateStaticFieldAndInstanceSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:94:15: Context: Previous declaration of 'duplicateStaticFieldAndInstanceSetter1'.
+//   static int? duplicateStaticFieldAndInstanceSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:99:15: Error: 'duplicateStaticFieldAndInstanceSetter2' is already declared in this scope.
+//   static int? duplicateStaticFieldAndInstanceSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:98:21: Context: Previous declaration of 'duplicateStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:104:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:67:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:107:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndDuplicateSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:12: Error: 'extensionInstanceFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:109:12: Error: 'extensionInstanceFieldAndDuplicateSetter' is already declared in this scope.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:12: Context: Previous declaration of 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:108:12: Context: Previous declaration of 'extensionInstanceFieldAndDuplicateSetter'.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:19: Error: 'extensionStaticFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:112:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:112:14: Error: 'duplicateExtensionInstanceFieldAndSetter1' is already declared in this scope.
+//   final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndSetter1'.
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:115:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: 'duplicateExtensionInstanceFieldAndSetter2' is already declared in this scope.
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:115:14: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:19: Error: 'extensionStaticFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:19: Context: Previous declaration of 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:123:19: Context: Previous declaration of 'extensionStaticFieldAndDuplicateSetter'.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: 'extensionStaticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:127:21: Error: 'duplicateExtensionStaticFieldAndSetter1' is already declared in this scope.
+//   static final int? duplicateExtensionStaticFieldAndSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:126:15: Context: Previous declaration of 'duplicateExtensionStaticFieldAndSetter1'.
+//   static int? duplicateExtensionStaticFieldAndSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:131:15: Error: 'duplicateExtensionStaticFieldAndSetter2' is already declared in this scope.
+//   static int? duplicateExtensionStaticFieldAndSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:130:21: Context: Previous declaration of 'duplicateExtensionStaticFieldAndSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:19: Error: 'extensionStaticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:19: Context: Previous declaration of 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:19: Context: Previous declaration of 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:12: Error: 'extensionStaticFieldAndInstanceDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:146:12: Error: 'extensionStaticFieldAndInstanceDuplicateSetter' is already declared in this scope.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:89:12: Context: Previous declaration of 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:145:12: Context: Previous declaration of 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:148:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndStaticSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:151:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndStaticDuplicateSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:97:19: Error: 'extensionInstanceFieldAndStaticDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:19: Error: 'extensionInstanceFieldAndStaticDuplicateSetter' is already declared in this scope.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:19: Context: Previous declaration of 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:152:19: Context: Previous declaration of 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: 'duplicateExtensionInstanceFieldAndStaticSetter1' is already declared in this scope.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: 'duplicateExtensionInstanceFieldAndStaticSetter2' is already declared in this scope.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:164:21: Error: 'duplicateExtensionStaticFieldAndInstanceSetter1' is already declared in this scope.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:15: Context: Previous declaration of 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:15: Error: 'duplicateExtensionStaticFieldAndInstanceSetter2' is already declared in this scope.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:167:21: Context: Previous declaration of 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart: Error: 'topLevelFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 //
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
@@ -129,356 +295,806 @@
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:8:6: Error: Conflicts with setter 'topLevelFieldAndDuplicateSetter'.
-// int? topLevelFieldAndDuplicateSetter;
-//      ^
-//
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart:9:10: Error: Conflicts with the implicit setter of the field 'topLevelFieldAndDuplicateSetter'.
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:13:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:8:6: Error: Conflicts with setter 'topLevelFieldAndDuplicateSetter'.
+// int? topLevelFieldAndDuplicateSetter;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:14:10: Error: Conflicts with the implicit setter of the field 'duplicateTopLevelFieldAndSetter1'.
+// void set duplicateTopLevelFieldAndSetter1(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:6: Error: Conflicts with setter 'duplicateTopLevelFieldAndSetter1'.
+// int? duplicateTopLevelFieldAndSetter1;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:18:10: Error: Conflicts with the implicit setter of the field 'duplicateTopLevelFieldAndSetter2'.
+// void set duplicateTopLevelFieldAndSetter2(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:6: Error: Conflicts with setter 'duplicateTopLevelFieldAndSetter2'.
+// int? duplicateTopLevelFieldAndSetter2;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:21:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndSetter'.
 // void set topLevelLateFinalFieldAndSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:20:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndSetter'.
 // late final int? topLevelLateFinalFieldAndSetter;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:15:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
+// void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:23:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndDuplicateSetter'.
 // late final int? topLevelLateFinalFieldAndDuplicateSetter;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
-// void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
-//          ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:21:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:29:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndSetter'.
 //   void set instanceFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:20:8: Error: Conflicts with setter 'instanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:28:8: Error: Conflicts with setter 'instanceFieldAndSetter'.
 //   int? instanceFieldAndSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:33:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:23:8: Error: Conflicts with setter 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
+//   void set instanceFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:8: Error: Conflicts with setter 'instanceFieldAndDuplicateSetter'.
 //   int? instanceFieldAndDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
-//   void set instanceFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:37:12: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndSetter1'.
+//   void set duplicateInstanceFieldAndSetter1(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:28:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:8: Error: Conflicts with setter 'duplicateInstanceFieldAndSetter1'.
+//   int? duplicateInstanceFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:41:12: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndSetter2'.
+//   void set duplicateInstanceFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:40:8: Error: Conflicts with setter 'duplicateInstanceFieldAndSetter2'.
+//   int? duplicateInstanceFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:44:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndSetter'.
 //   void set instanceLateFinalFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:27:19: Error: Conflicts with setter 'instanceLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:43:19: Error: Conflicts with setter 'instanceLateFinalFieldAndSetter'.
 //   late final int? instanceLateFinalFieldAndSetter;
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:30:19: Error: Conflicts with setter 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:47:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
+//   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: Conflicts with setter 'instanceLateFinalFieldAndDuplicateSetter'.
 //   late final int? instanceLateFinalFieldAndDuplicateSetter;
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
-//   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:51:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndSetter'.
 //   static void set staticFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:34:15: Error: Conflicts with setter 'staticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:50:15: Error: Conflicts with setter 'staticFieldAndSetter'.
 //   static int? staticFieldAndSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:37:15: Error: Conflicts with setter 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:54:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
+//   static void set staticFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:15: Error: Conflicts with setter 'staticFieldAndDuplicateSetter'.
 //   static int? staticFieldAndDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:38:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
-//   static void set staticFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndSetter1'.
+//   static void set duplicateStaticFieldAndSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:42:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:57:15: Error: Conflicts with setter 'duplicateStaticFieldAndSetter1'.
+//   static int? duplicateStaticFieldAndSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:63:19: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndSetter2'.
+//   static void set duplicateStaticFieldAndSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:62:15: Error: Conflicts with setter 'duplicateStaticFieldAndSetter2'.
+//   static int? duplicateStaticFieldAndSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:66:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndSetter'.
 //   static void set staticLateFinalFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:41:26: Error: Conflicts with setter 'staticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:65:26: Error: Conflicts with setter 'staticLateFinalFieldAndSetter'.
 //   static late final int? staticLateFinalFieldAndSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:70:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:44:26: Error: Conflicts with setter 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
+//   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:26: Error: Conflicts with setter 'staticLateFinalFieldAndDuplicateSetter'.
 //   static late final int? staticLateFinalFieldAndDuplicateSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:45:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
-//   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
-//                   ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:49:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:73:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceSetter'.
 //   void set staticFieldAndInstanceSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:15: Error: Conflicts with setter 'staticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:72:15: Error: Conflicts with setter 'staticFieldAndInstanceSetter'.
 //   static int? staticFieldAndInstanceSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:77:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:51:15: Error: Conflicts with setter 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
+//   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:15: Error: Conflicts with setter 'staticFieldAndInstanceDuplicateSetter'.
 //   static int? staticFieldAndInstanceDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:52:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
-//   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:56:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:80:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticSetter'.
 //   static void set instanceFieldAndStaticSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:8: Error: Conflicts with setter 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:79:8: Error: Conflicts with setter 'instanceFieldAndStaticSetter'.
 //   int? instanceFieldAndStaticSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:60:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:84:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:58:8: Error: Conflicts with setter 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
+//   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:8: Error: Conflicts with setter 'instanceFieldAndStaticDuplicateSetter'.
 //   int? instanceFieldAndStaticDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
-//   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:88:19: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndStaticSetter1'.
+//   static void set duplicateInstanceFieldAndStaticSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:65:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:8: Error: Conflicts with setter 'duplicateInstanceFieldAndStaticSetter1'.
+//   int? duplicateInstanceFieldAndStaticSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:19: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndStaticSetter2'.
+//   static void set duplicateInstanceFieldAndStaticSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:91:8: Error: Conflicts with setter 'duplicateInstanceFieldAndStaticSetter2'.
+//   int? duplicateInstanceFieldAndStaticSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:12: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndInstanceSetter1'.
+//   void set duplicateStaticFieldAndInstanceSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:94:15: Error: Conflicts with setter 'duplicateStaticFieldAndInstanceSetter1'.
+//   static int? duplicateStaticFieldAndInstanceSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:100:12: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndInstanceSetter2'.
+//   void set duplicateStaticFieldAndInstanceSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:99:15: Error: Conflicts with setter 'duplicateStaticFieldAndInstanceSetter2'.
+//   static int? duplicateStaticFieldAndInstanceSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:105:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndSetter'.
 //   void set extensionInstanceFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:64:8: Error: Conflicts with setter 'extensionInstanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:104:8: Error: Conflicts with setter 'extensionInstanceFieldAndSetter'.
 //   int? extensionInstanceFieldAndSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:109:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:67:8: Error: Conflicts with setter 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:108:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
+//   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:107:8: Error: Conflicts with setter 'extensionInstanceFieldAndDuplicateSetter'.
 //   int? extensionInstanceFieldAndDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
-//   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:113:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndSetter1'.
+//   void set duplicateExtensionInstanceFieldAndSetter1(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:72:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndSetter1'.
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:117:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndSetter2'.
+//   void set duplicateExtensionInstanceFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndSetter2'.
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:120:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndSetter'.
 //   static void set extensionStaticFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:71:15: Error: Conflicts with setter 'extensionStaticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:119:15: Error: Conflicts with setter 'extensionStaticFieldAndSetter'.
 //   static int? extensionStaticFieldAndSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:74:15: Error: Conflicts with setter 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:123:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
+//   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:122:15: Error: Conflicts with setter 'extensionStaticFieldAndDuplicateSetter'.
 //   static int? extensionStaticFieldAndDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
-//   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:128:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndSetter1'.
+//   static void set duplicateExtensionStaticFieldAndSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:79:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:126:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndSetter1'.
+//   static int? duplicateExtensionStaticFieldAndSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndSetter2'.
+//   static void set duplicateExtensionStaticFieldAndSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:131:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndSetter2'.
+//   static int? duplicateExtensionStaticFieldAndSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:135:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndSetter'.
 //   static void set extensionStaticLateFinalFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:78:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:134:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndSetter'.
 //   static late final int? extensionStaticLateFinalFieldAndSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:81:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+//   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static late final int? extensionStaticLateFinalFieldAndDuplicateSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
-//   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
-//                   ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:142:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceSetter'.
 //   void set extensionStaticFieldAndInstanceSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:85:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:141:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceSetter'.
 //   static int? extensionStaticFieldAndInstanceSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:146:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:88:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:145:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
+//   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:144:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   static int? extensionStaticFieldAndInstanceDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:89:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
-//   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:93:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:149:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticSetter'.
 //   static void set extensionInstanceFieldAndStaticSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:148:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticSetter'.
 //   int? extensionInstanceFieldAndStaticSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:97:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:152:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
+//   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:151:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   int? extensionInstanceFieldAndStaticDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
-//   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:157:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   static void set duplicateExtensionInstanceFieldAndStaticSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:129:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:161:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   static void set duplicateExtensionInstanceFieldAndStaticSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   void set duplicateExtensionStaticFieldAndInstanceSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:164:21: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+//                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:169:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   void set duplicateExtensionStaticFieldAndInstanceSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:167:21: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+//                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:38: Error: Can't use 'duplicateTopLevelFieldAndSetter1' because it is declared more than once.
+//   duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+//                                      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:36: Error: Can't assign to this.
+//   duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:38: Error: Can't use 'duplicateTopLevelFieldAndSetter2' because it is declared more than once.
+//   duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+//                                      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:36: Error: Can't assign to this.
+//   duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:9: Error: Can't use 'duplicateStaticFieldAndSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:48: Error: Can't use 'duplicateStaticFieldAndSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:40: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//                                        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:9: Error: Can't use 'duplicateStaticFieldAndSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:48: Error: Can't use 'duplicateStaticFieldAndSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:40: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//                                        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:209:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
 //   Class.instanceFieldAndStaticSetter = c.instanceFieldAndStaticSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:9: Error: Can't use 'instanceFieldAndStaticDuplicateSetter' because it is declared more than once.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:9: Error: Can't use 'instanceFieldAndStaticDuplicateSetter' because it is declared more than once.
 //   Class.instanceFieldAndStaticDuplicateSetter =
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:47: Error: Can't assign to this.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:47: Error: Can't assign to this.
 //   Class.instanceFieldAndStaticDuplicateSetter =
 //                                               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:218:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter1;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:9: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndInstanceSetter1 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:220:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter1;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:48: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndInstanceSetter1 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:223:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter2;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:9: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndInstanceSetter2 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:225:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter2;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:48: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndInstanceSetter2 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   Class.duplicateInstanceFieldAndStaticSetter1 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:48: Error: Can't assign to this.
+//   Class.duplicateInstanceFieldAndStaticSetter1 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   Class.duplicateInstanceFieldAndStaticSetter2 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:48: Error: Can't assign to this.
+//   Class.duplicateInstanceFieldAndStaticSetter2 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:13: Error: Can't use 'duplicateExtensionStaticFieldAndSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:253:17: Error: Can't use 'duplicateExtensionStaticFieldAndSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:53: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndSetter1 =
+//                                                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:13: Error: Can't use 'duplicateExtensionStaticFieldAndSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:255:17: Error: Can't use 'duplicateExtensionStaticFieldAndSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:53: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndSetter2 =
+//                                                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:267:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
 //   Extension.extensionInstanceFieldAndStaticSetter =
 //             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:13: Error: Can't use 'extensionInstanceFieldAndStaticDuplicateSetter' because it is declared more than once.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:13: Error: Can't use 'extensionInstanceFieldAndStaticDuplicateSetter' because it is declared more than once.
 //   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
 //             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:60: Error: Can't assign to this.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:60: Error: Can't assign to this.
 //   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
 //                                                            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:121:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:13: Error: Can't use 'duplicateExtensionInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:13: Error: Can't use 'duplicateExtensionInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:13: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:288:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:290:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:13: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:293:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:295:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   c.duplicateInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:189:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//       c.duplicateInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:189:9: Error: The getter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+//       c.duplicateInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+//   c.duplicateInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   c.duplicateInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:191:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//       c.duplicateInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:191:9: Error: The getter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+//       c.duplicateInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+//   c.duplicateInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:201:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
 //  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceSetter'.
 //   c.staticFieldAndInstanceSetter = Class.staticFieldAndInstanceSetter;
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:204:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
 //  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceDuplicateSetter'.
 //   c.staticFieldAndInstanceDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:41: Error: The getter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:217:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter1'.
+//   c.duplicateStaticFieldAndInstanceSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:222:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter2'.
+//   c.duplicateStaticFieldAndInstanceSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:41: Error: The getter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndSetter'.
 //   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
 //                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndSetter'.
 //   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:9: Error: The getter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:234:9: Error: The getter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndDuplicateSetter'.
 //       0.extensionInstanceFieldAndDuplicateSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:233:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndDuplicateSetter'.
 //   0.extensionInstanceFieldAndDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:237:9: Error: The getter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+//       0.duplicateExtensionInstanceFieldAndSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:236:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+//   0.duplicateExtensionInstanceFieldAndSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:239:9: Error: The getter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+//       0.duplicateExtensionInstanceFieldAndSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:238:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+//   0.duplicateExtensionInstanceFieldAndSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:257:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceSetter'.
 //   0.extensionStaticFieldAndInstanceSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:158:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:262:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   0.extensionStaticFieldAndInstanceDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:166:9: Error: The getter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:270:9: Error: The getter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndStaticSetter'.
 //       0.extensionInstanceFieldAndStaticSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:269:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticSetter'.
 //   0.extensionInstanceFieldAndStaticSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:171:9: Error: The getter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:275:9: Error: The getter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //       0.extensionInstanceFieldAndStaticDuplicateSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:170:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:274:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   0.extensionInstanceFieldAndStaticDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:280:9: Error: The getter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//       0.duplicateExtensionInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:279:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   0.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:285:9: Error: The getter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//       0.duplicateExtensionInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:284:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   0.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:289:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   0.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:294:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   0.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:14: Error: Final field 'duplicateInstanceFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? duplicateInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:61:21: Error: Final field 'duplicateStaticFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   static final int? duplicateStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:14: Error: Final field 'duplicateInstanceFieldAndStaticSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? duplicateInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:98:21: Error: Final field 'duplicateStaticFieldAndInstanceSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   static final int? duplicateStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
 import self as self;
 import "dart:core" as core;
 
 class Class extends core::Object {
   field core::int? instanceFieldAndSetter = null;
   field core::int? instanceFieldAndDuplicateSetter = null;
+  field core::int? duplicateInstanceFieldAndSetter1 = null;
+  final field core::int? duplicateInstanceFieldAndSetter2 = null;
   late final [setter] field core::int? instanceLateFinalFieldAndSetter;
   late final [setter] field core::int? instanceLateFinalFieldAndDuplicateSetter;
   static field core::int? staticFieldAndSetter = null;
   static field core::int? staticFieldAndDuplicateSetter = null;
+  static field core::int? duplicateStaticFieldAndSetter1 = null;
+  static final field core::int? duplicateStaticFieldAndSetter2 = null;
   late static final [setter] field core::int? staticLateFinalFieldAndSetter;
   late static final [setter] field core::int? staticLateFinalFieldAndDuplicateSetter;
   static field core::int? staticFieldAndInstanceSetter = null;
   static field core::int? staticFieldAndInstanceDuplicateSetter = null;
   field core::int? instanceFieldAndStaticSetter = null;
   field core::int? instanceFieldAndStaticDuplicateSetter = null;
+  field core::int? duplicateInstanceFieldAndStaticSetter1 = null;
+  final field core::int? duplicateInstanceFieldAndStaticSetter2 = null;
+  static field core::int? duplicateStaticFieldAndInstanceSetter1 = null;
+  static final field core::int? duplicateStaticFieldAndInstanceSetter2 = null;
   synthetic constructor •() → self::Class
     : super core::Object::•()
     ;
@@ -486,100 +1102,204 @@
 extension Extension on core::int? {
   field extensionInstanceFieldAndSetter = self::Extension|extensionInstanceFieldAndSetter;
   field extensionInstanceFieldAndDuplicateSetter = self::Extension|extensionInstanceFieldAndDuplicateSetter;
+  field duplicateExtensionInstanceFieldAndSetter1 = self::Extension|duplicateExtensionInstanceFieldAndSetter1;
+  field duplicateExtensionInstanceFieldAndSetter2 = self::Extension|duplicateExtensionInstanceFieldAndSetter2;
   static field extensionStaticFieldAndSetter = self::Extension|extensionStaticFieldAndSetter;
   static field extensionStaticFieldAndDuplicateSetter = self::Extension|extensionStaticFieldAndDuplicateSetter;
+  static field duplicateExtensionStaticFieldAndSetter1 = self::Extension|duplicateExtensionStaticFieldAndSetter1;
+  static field duplicateExtensionStaticFieldAndSetter2 = self::Extension|duplicateExtensionStaticFieldAndSetter2;
   static field extensionStaticLateFinalFieldAndSetter = self::Extension|extensionStaticLateFinalFieldAndSetter;
   static field extensionStaticLateFinalFieldAndDuplicateSetter = self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
   static field extensionStaticFieldAndInstanceSetter = self::Extension|extensionStaticFieldAndInstanceSetter;
   static field extensionStaticFieldAndInstanceDuplicateSetter = self::Extension|extensionStaticFieldAndInstanceDuplicateSetter;
   field extensionInstanceFieldAndStaticSetter = self::Extension|extensionInstanceFieldAndStaticSetter;
   field extensionInstanceFieldAndStaticDuplicateSetter = self::Extension|extensionInstanceFieldAndStaticDuplicateSetter;
+  field duplicateExtensionInstanceFieldAndStaticSetter1 = self::Extension|duplicateExtensionInstanceFieldAndStaticSetter1;
+  field duplicateExtensionInstanceFieldAndStaticSetter2 = self::Extension|duplicateExtensionInstanceFieldAndStaticSetter2;
+  static field duplicateExtensionStaticFieldAndInstanceSetter1 = self::Extension|duplicateExtensionStaticFieldAndInstanceSetter1;
+  static field duplicateExtensionStaticFieldAndInstanceSetter2 = self::Extension|duplicateExtensionStaticFieldAndInstanceSetter2;
 }
 static field core::int? topLevelFieldAndSetter;
 static field core::int? topLevelFieldAndDuplicateSetter;
+static field core::int? duplicateTopLevelFieldAndSetter1;
+static final field core::int? duplicateTopLevelFieldAndSetter2;
 late static final [setter] field core::int? topLevelLateFinalFieldAndSetter;
 late static final [setter] field core::int? topLevelLateFinalFieldAndDuplicateSetter;
 static field core::int? Extension|extensionInstanceFieldAndSetter;
 static field core::int? Extension|extensionInstanceFieldAndDuplicateSetter;
+static field core::int? Extension|duplicateExtensionInstanceFieldAndSetter1;
+static final field core::int? Extension|duplicateExtensionInstanceFieldAndSetter2;
 static field core::int? Extension|extensionStaticFieldAndSetter;
 static field core::int? Extension|extensionStaticFieldAndDuplicateSetter;
+static field core::int? Extension|duplicateExtensionStaticFieldAndSetter1;
+static final field core::int? Extension|duplicateExtensionStaticFieldAndSetter2;
 late static final [setter] field core::int? Extension|extensionStaticLateFinalFieldAndSetter;
 late static final [setter] field core::int? Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
 static field core::int? Extension|extensionStaticFieldAndInstanceSetter;
 static field core::int? Extension|extensionStaticFieldAndInstanceDuplicateSetter;
 static field core::int? Extension|extensionInstanceFieldAndStaticSetter;
 static field core::int? Extension|extensionInstanceFieldAndStaticDuplicateSetter;
+static field core::int? Extension|duplicateExtensionInstanceFieldAndStaticSetter1;
+static final field core::int? Extension|duplicateExtensionInstanceFieldAndStaticSetter2;
+static field core::int? Extension|duplicateExtensionStaticFieldAndInstanceSetter1;
+static final field core::int? Extension|duplicateExtensionStaticFieldAndInstanceSetter2;
 static const field dynamic _exports# = #C1 /*isLegacy, from null */;
 static method test() → dynamic {
   self::topLevelFieldAndSetter = self::topLevelFieldAndSetter;
   self::topLevelFieldAndDuplicateSetter = self::topLevelFieldAndDuplicateSetter;
   self::topLevelLateFinalFieldAndSetter = self::topLevelLateFinalFieldAndSetter;
   self::topLevelLateFinalFieldAndDuplicateSetter = self::topLevelLateFinalFieldAndDuplicateSetter;
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:36: Error: Can't assign to this.
+  duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+                                   ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:36: Error: Can't assign to this.
+  duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+                                   ^";
   self::Class c = new self::Class::•();
   c.{self::Class::instanceFieldAndSetter} = c.{self::Class::instanceFieldAndSetter};
   c.{self::Class::instanceFieldAndDuplicateSetter} = c.{self::Class::instanceFieldAndDuplicateSetter};
   c.{self::Class::instanceLateFinalFieldAndSetter} = c.{self::Class::instanceLateFinalFieldAndSetter};
   c.{self::Class::instanceLateFinalFieldAndDuplicateSetter} = c.{self::Class::instanceLateFinalFieldAndDuplicateSetter};
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+  c.duplicateInstanceFieldAndStaticSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+  c.duplicateInstanceFieldAndStaticSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndSetter = self::Class::staticFieldAndSetter;
   self::Class::staticFieldAndDuplicateSetter = self::Class::staticFieldAndDuplicateSetter;
   self::Class::staticLateFinalFieldAndSetter = self::Class::staticLateFinalFieldAndSetter;
   self::Class::staticLateFinalFieldAndDuplicateSetter = self::Class::staticLateFinalFieldAndDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:121:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:40: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+                                       ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:40: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+                                       ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:201:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceSetter'.
   c.staticFieldAndInstanceSetter = Class.staticFieldAndInstanceSetter;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndInstanceSetter = self::Class::staticFieldAndInstanceSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:204:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceDuplicateSetter'.
   c.staticFieldAndInstanceDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndInstanceDuplicateSetter = self::Class::staticFieldAndInstanceDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:129:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:209:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
   Class.instanceFieldAndStaticSetter = c.instanceFieldAndStaticSetter;
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   c.{self::Class::instanceFieldAndStaticSetter} = c.{self::Class::instanceFieldAndStaticSetter};
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:47: Error: Can't assign to this.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:47: Error: Can't assign to this.
   Class.instanceFieldAndStaticDuplicateSetter =
                                               ^";
   c.{self::Class::instanceFieldAndStaticDuplicateSetter} = c.{self::Class::instanceFieldAndStaticDuplicateSetter};
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:217:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter1'.
+  c.duplicateStaticFieldAndInstanceSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:48: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndInstanceSetter1 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:222:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter2'.
+  c.duplicateStaticFieldAndInstanceSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:48: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndInstanceSetter2 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:48: Error: Can't assign to this.
+  Class.duplicateInstanceFieldAndStaticSetter1 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:48: Error: Can't assign to this.
+  Class.duplicateInstanceFieldAndStaticSetter2 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndSetter'.
   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:233:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndDuplicateSetter'.
   0.extensionInstanceFieldAndDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:236:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+  0.duplicateExtensionInstanceFieldAndSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:238:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+  0.duplicateExtensionInstanceFieldAndSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndSetter = self::Extension|extensionStaticFieldAndSetter;
   self::Extension|extensionStaticFieldAndDuplicateSetter = self::Extension|extensionStaticFieldAndDuplicateSetter;
   self::Extension|extensionStaticLateFinalFieldAndSetter = self::Extension|extensionStaticLateFinalFieldAndSetter;
   self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter = self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:53: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndSetter1 =
+                                                    ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:53: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndSetter2 =
+                                                    ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:257:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceSetter'.
   0.extensionStaticFieldAndInstanceSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndInstanceSetter = self::Extension|extensionStaticFieldAndInstanceSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:158:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:262:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceDuplicateSetter'.
   0.extensionStaticFieldAndInstanceDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndInstanceDuplicateSetter = self::Extension|extensionStaticFieldAndInstanceDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:267:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
   Extension.extensionInstanceFieldAndStaticSetter =
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:269:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticSetter'.
   0.extensionInstanceFieldAndStaticSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:60: Error: Can't assign to this.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:60: Error: Can't assign to this.
   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
                                                            ^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:170:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:274:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
   0.extensionInstanceFieldAndStaticDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:61: Error: Can't assign to this.
+  Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:279:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+  0.duplicateExtensionInstanceFieldAndStaticSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:61: Error: Can't assign to this.
+  Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:284:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+  0.duplicateExtensionInstanceFieldAndStaticSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:61: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:289:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+  0.duplicateExtensionStaticFieldAndInstanceSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:61: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:294:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+  0.duplicateExtensionStaticFieldAndInstanceSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.strong.transformed.expect
index f523434..4827498 100644
--- a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.strong.transformed.expect
@@ -9,110 +9,276 @@
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:10: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:13:12: Error: 'duplicateTopLevelFieldAndSetter1' is already declared in this scope.
+// final int? duplicateTopLevelFieldAndSetter1 = null;
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:6: Context: Previous declaration of 'duplicateTopLevelFieldAndSetter1'.
+// int? duplicateTopLevelFieldAndSetter1;
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:6: Error: 'duplicateTopLevelFieldAndSetter2' is already declared in this scope.
+// int? duplicateTopLevelFieldAndSetter2;
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:12: Context: Previous declaration of 'duplicateTopLevelFieldAndSetter2'.
+// final int? duplicateTopLevelFieldAndSetter2 = null;
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:10: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:10: Context: Previous declaration of 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:10: Context: Previous declaration of 'topLevelLateFinalFieldAndDuplicateSetter'.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:12: Error: 'instanceFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:33:12: Error: 'instanceFieldAndDuplicateSetter' is already declared in this scope.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:12: Context: Previous declaration of 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Context: Previous declaration of 'instanceFieldAndDuplicateSetter'.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: 'instanceLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:36:14: Error: 'duplicateInstanceFieldAndSetter1' is already declared in this scope.
+//   final int? duplicateInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:8: Context: Previous declaration of 'duplicateInstanceFieldAndSetter1'.
+//   int? duplicateInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:40:8: Error: 'duplicateInstanceFieldAndSetter2' is already declared in this scope.
+//   int? duplicateInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:14: Context: Previous declaration of 'duplicateInstanceFieldAndSetter2'.
+//   final int? duplicateInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:12: Error: 'instanceLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:12: Context: Previous declaration of 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:47:12: Context: Previous declaration of 'instanceLateFinalFieldAndDuplicateSetter'.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:19: Error: 'staticFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:19: Error: 'staticFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:38:19: Context: Previous declaration of 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:54:19: Context: Previous declaration of 'staticFieldAndDuplicateSetter'.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: 'staticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:58:21: Error: 'duplicateStaticFieldAndSetter1' is already declared in this scope.
+//   static final int? duplicateStaticFieldAndSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:57:15: Context: Previous declaration of 'duplicateStaticFieldAndSetter1'.
+//   static int? duplicateStaticFieldAndSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:62:15: Error: 'duplicateStaticFieldAndSetter2' is already declared in this scope.
+//   static int? duplicateStaticFieldAndSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:61:21: Context: Previous declaration of 'duplicateStaticFieldAndSetter2'.
+//   static final int? duplicateStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:70:19: Error: 'staticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:45:19: Context: Previous declaration of 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:19: Context: Previous declaration of 'staticLateFinalFieldAndDuplicateSetter'.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:12: Error: 'staticFieldAndInstanceDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:77:12: Error: 'staticFieldAndInstanceDuplicateSetter' is already declared in this scope.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:52:12: Context: Previous declaration of 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:12: Context: Previous declaration of 'staticFieldAndInstanceDuplicateSetter'.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:60:19: Error: 'instanceFieldAndStaticDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:84:19: Error: 'instanceFieldAndStaticDuplicateSetter' is already declared in this scope.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Context: Previous declaration of 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Context: Previous declaration of 'instanceFieldAndStaticDuplicateSetter'.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:64:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:87:14: Error: 'duplicateInstanceFieldAndStaticSetter1' is already declared in this scope.
+//   final int? duplicateInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:8: Context: Previous declaration of 'duplicateInstanceFieldAndStaticSetter1'.
+//   int? duplicateInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:91:8: Error: 'duplicateInstanceFieldAndStaticSetter2' is already declared in this scope.
+//   int? duplicateInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:14: Context: Previous declaration of 'duplicateInstanceFieldAndStaticSetter2'.
+//   final int? duplicateInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:21: Error: 'duplicateStaticFieldAndInstanceSetter1' is already declared in this scope.
+//   static final int? duplicateStaticFieldAndInstanceSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:94:15: Context: Previous declaration of 'duplicateStaticFieldAndInstanceSetter1'.
+//   static int? duplicateStaticFieldAndInstanceSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:99:15: Error: 'duplicateStaticFieldAndInstanceSetter2' is already declared in this scope.
+//   static int? duplicateStaticFieldAndInstanceSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:98:21: Context: Previous declaration of 'duplicateStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:104:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:67:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:107:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndDuplicateSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:12: Error: 'extensionInstanceFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:109:12: Error: 'extensionInstanceFieldAndDuplicateSetter' is already declared in this scope.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:12: Context: Previous declaration of 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:108:12: Context: Previous declaration of 'extensionInstanceFieldAndDuplicateSetter'.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:19: Error: 'extensionStaticFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:112:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:112:14: Error: 'duplicateExtensionInstanceFieldAndSetter1' is already declared in this scope.
+//   final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndSetter1'.
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:115:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: 'duplicateExtensionInstanceFieldAndSetter2' is already declared in this scope.
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:115:14: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:19: Error: 'extensionStaticFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:19: Context: Previous declaration of 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:123:19: Context: Previous declaration of 'extensionStaticFieldAndDuplicateSetter'.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: 'extensionStaticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:127:21: Error: 'duplicateExtensionStaticFieldAndSetter1' is already declared in this scope.
+//   static final int? duplicateExtensionStaticFieldAndSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:126:15: Context: Previous declaration of 'duplicateExtensionStaticFieldAndSetter1'.
+//   static int? duplicateExtensionStaticFieldAndSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:131:15: Error: 'duplicateExtensionStaticFieldAndSetter2' is already declared in this scope.
+//   static int? duplicateExtensionStaticFieldAndSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:130:21: Context: Previous declaration of 'duplicateExtensionStaticFieldAndSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:19: Error: 'extensionStaticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:19: Context: Previous declaration of 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:19: Context: Previous declaration of 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:12: Error: 'extensionStaticFieldAndInstanceDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:146:12: Error: 'extensionStaticFieldAndInstanceDuplicateSetter' is already declared in this scope.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:89:12: Context: Previous declaration of 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:145:12: Context: Previous declaration of 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:148:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndStaticSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:151:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndStaticDuplicateSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:97:19: Error: 'extensionInstanceFieldAndStaticDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:19: Error: 'extensionInstanceFieldAndStaticDuplicateSetter' is already declared in this scope.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:19: Context: Previous declaration of 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:152:19: Context: Previous declaration of 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: 'duplicateExtensionInstanceFieldAndStaticSetter1' is already declared in this scope.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: 'duplicateExtensionInstanceFieldAndStaticSetter2' is already declared in this scope.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:164:21: Error: 'duplicateExtensionStaticFieldAndInstanceSetter1' is already declared in this scope.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:15: Context: Previous declaration of 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:15: Error: 'duplicateExtensionStaticFieldAndInstanceSetter2' is already declared in this scope.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:167:21: Context: Previous declaration of 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart: Error: 'topLevelFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 //
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
@@ -129,356 +295,806 @@
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:8:6: Error: Conflicts with setter 'topLevelFieldAndDuplicateSetter'.
-// int? topLevelFieldAndDuplicateSetter;
-//      ^
-//
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart:9:10: Error: Conflicts with the implicit setter of the field 'topLevelFieldAndDuplicateSetter'.
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:13:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:8:6: Error: Conflicts with setter 'topLevelFieldAndDuplicateSetter'.
+// int? topLevelFieldAndDuplicateSetter;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:14:10: Error: Conflicts with the implicit setter of the field 'duplicateTopLevelFieldAndSetter1'.
+// void set duplicateTopLevelFieldAndSetter1(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:6: Error: Conflicts with setter 'duplicateTopLevelFieldAndSetter1'.
+// int? duplicateTopLevelFieldAndSetter1;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:18:10: Error: Conflicts with the implicit setter of the field 'duplicateTopLevelFieldAndSetter2'.
+// void set duplicateTopLevelFieldAndSetter2(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:6: Error: Conflicts with setter 'duplicateTopLevelFieldAndSetter2'.
+// int? duplicateTopLevelFieldAndSetter2;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:21:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndSetter'.
 // void set topLevelLateFinalFieldAndSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:20:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndSetter'.
 // late final int? topLevelLateFinalFieldAndSetter;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:15:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
+// void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:23:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndDuplicateSetter'.
 // late final int? topLevelLateFinalFieldAndDuplicateSetter;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
-// void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
-//          ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:21:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:29:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndSetter'.
 //   void set instanceFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:20:8: Error: Conflicts with setter 'instanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:28:8: Error: Conflicts with setter 'instanceFieldAndSetter'.
 //   int? instanceFieldAndSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:33:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:23:8: Error: Conflicts with setter 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
+//   void set instanceFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:8: Error: Conflicts with setter 'instanceFieldAndDuplicateSetter'.
 //   int? instanceFieldAndDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
-//   void set instanceFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:37:12: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndSetter1'.
+//   void set duplicateInstanceFieldAndSetter1(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:28:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:8: Error: Conflicts with setter 'duplicateInstanceFieldAndSetter1'.
+//   int? duplicateInstanceFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:41:12: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndSetter2'.
+//   void set duplicateInstanceFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:40:8: Error: Conflicts with setter 'duplicateInstanceFieldAndSetter2'.
+//   int? duplicateInstanceFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:44:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndSetter'.
 //   void set instanceLateFinalFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:27:19: Error: Conflicts with setter 'instanceLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:43:19: Error: Conflicts with setter 'instanceLateFinalFieldAndSetter'.
 //   late final int? instanceLateFinalFieldAndSetter;
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:30:19: Error: Conflicts with setter 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:47:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
+//   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: Conflicts with setter 'instanceLateFinalFieldAndDuplicateSetter'.
 //   late final int? instanceLateFinalFieldAndDuplicateSetter;
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
-//   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:51:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndSetter'.
 //   static void set staticFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:34:15: Error: Conflicts with setter 'staticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:50:15: Error: Conflicts with setter 'staticFieldAndSetter'.
 //   static int? staticFieldAndSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:37:15: Error: Conflicts with setter 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:54:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
+//   static void set staticFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:15: Error: Conflicts with setter 'staticFieldAndDuplicateSetter'.
 //   static int? staticFieldAndDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:38:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
-//   static void set staticFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndSetter1'.
+//   static void set duplicateStaticFieldAndSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:42:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:57:15: Error: Conflicts with setter 'duplicateStaticFieldAndSetter1'.
+//   static int? duplicateStaticFieldAndSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:63:19: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndSetter2'.
+//   static void set duplicateStaticFieldAndSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:62:15: Error: Conflicts with setter 'duplicateStaticFieldAndSetter2'.
+//   static int? duplicateStaticFieldAndSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:66:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndSetter'.
 //   static void set staticLateFinalFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:41:26: Error: Conflicts with setter 'staticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:65:26: Error: Conflicts with setter 'staticLateFinalFieldAndSetter'.
 //   static late final int? staticLateFinalFieldAndSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:70:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:44:26: Error: Conflicts with setter 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
+//   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:26: Error: Conflicts with setter 'staticLateFinalFieldAndDuplicateSetter'.
 //   static late final int? staticLateFinalFieldAndDuplicateSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:45:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
-//   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
-//                   ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:49:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:73:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceSetter'.
 //   void set staticFieldAndInstanceSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:15: Error: Conflicts with setter 'staticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:72:15: Error: Conflicts with setter 'staticFieldAndInstanceSetter'.
 //   static int? staticFieldAndInstanceSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:77:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:51:15: Error: Conflicts with setter 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
+//   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:15: Error: Conflicts with setter 'staticFieldAndInstanceDuplicateSetter'.
 //   static int? staticFieldAndInstanceDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:52:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
-//   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:56:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:80:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticSetter'.
 //   static void set instanceFieldAndStaticSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:8: Error: Conflicts with setter 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:79:8: Error: Conflicts with setter 'instanceFieldAndStaticSetter'.
 //   int? instanceFieldAndStaticSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:60:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:84:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:58:8: Error: Conflicts with setter 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
+//   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:8: Error: Conflicts with setter 'instanceFieldAndStaticDuplicateSetter'.
 //   int? instanceFieldAndStaticDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
-//   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:88:19: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndStaticSetter1'.
+//   static void set duplicateInstanceFieldAndStaticSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:65:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:8: Error: Conflicts with setter 'duplicateInstanceFieldAndStaticSetter1'.
+//   int? duplicateInstanceFieldAndStaticSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:19: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndStaticSetter2'.
+//   static void set duplicateInstanceFieldAndStaticSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:91:8: Error: Conflicts with setter 'duplicateInstanceFieldAndStaticSetter2'.
+//   int? duplicateInstanceFieldAndStaticSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:12: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndInstanceSetter1'.
+//   void set duplicateStaticFieldAndInstanceSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:94:15: Error: Conflicts with setter 'duplicateStaticFieldAndInstanceSetter1'.
+//   static int? duplicateStaticFieldAndInstanceSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:100:12: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndInstanceSetter2'.
+//   void set duplicateStaticFieldAndInstanceSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:99:15: Error: Conflicts with setter 'duplicateStaticFieldAndInstanceSetter2'.
+//   static int? duplicateStaticFieldAndInstanceSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:105:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndSetter'.
 //   void set extensionInstanceFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:64:8: Error: Conflicts with setter 'extensionInstanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:104:8: Error: Conflicts with setter 'extensionInstanceFieldAndSetter'.
 //   int? extensionInstanceFieldAndSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:109:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:67:8: Error: Conflicts with setter 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:108:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
+//   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:107:8: Error: Conflicts with setter 'extensionInstanceFieldAndDuplicateSetter'.
 //   int? extensionInstanceFieldAndDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
-//   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:113:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndSetter1'.
+//   void set duplicateExtensionInstanceFieldAndSetter1(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:72:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndSetter1'.
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:117:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndSetter2'.
+//   void set duplicateExtensionInstanceFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndSetter2'.
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:120:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndSetter'.
 //   static void set extensionStaticFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:71:15: Error: Conflicts with setter 'extensionStaticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:119:15: Error: Conflicts with setter 'extensionStaticFieldAndSetter'.
 //   static int? extensionStaticFieldAndSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:74:15: Error: Conflicts with setter 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:123:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
+//   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:122:15: Error: Conflicts with setter 'extensionStaticFieldAndDuplicateSetter'.
 //   static int? extensionStaticFieldAndDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
-//   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:128:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndSetter1'.
+//   static void set duplicateExtensionStaticFieldAndSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:79:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:126:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndSetter1'.
+//   static int? duplicateExtensionStaticFieldAndSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndSetter2'.
+//   static void set duplicateExtensionStaticFieldAndSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:131:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndSetter2'.
+//   static int? duplicateExtensionStaticFieldAndSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:135:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndSetter'.
 //   static void set extensionStaticLateFinalFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:78:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:134:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndSetter'.
 //   static late final int? extensionStaticLateFinalFieldAndSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:81:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+//   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static late final int? extensionStaticLateFinalFieldAndDuplicateSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
-//   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
-//                   ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:142:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceSetter'.
 //   void set extensionStaticFieldAndInstanceSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:85:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:141:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceSetter'.
 //   static int? extensionStaticFieldAndInstanceSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:146:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:88:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:145:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
+//   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:144:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   static int? extensionStaticFieldAndInstanceDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:89:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
-//   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:93:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:149:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticSetter'.
 //   static void set extensionInstanceFieldAndStaticSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:148:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticSetter'.
 //   int? extensionInstanceFieldAndStaticSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:97:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:152:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
+//   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:151:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   int? extensionInstanceFieldAndStaticDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
-//   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:157:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   static void set duplicateExtensionInstanceFieldAndStaticSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:129:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:161:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   static void set duplicateExtensionInstanceFieldAndStaticSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   void set duplicateExtensionStaticFieldAndInstanceSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:164:21: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+//                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:169:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   void set duplicateExtensionStaticFieldAndInstanceSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:167:21: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+//                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:38: Error: Can't use 'duplicateTopLevelFieldAndSetter1' because it is declared more than once.
+//   duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+//                                      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:36: Error: Can't assign to this.
+//   duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:38: Error: Can't use 'duplicateTopLevelFieldAndSetter2' because it is declared more than once.
+//   duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+//                                      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:36: Error: Can't assign to this.
+//   duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:9: Error: Can't use 'duplicateStaticFieldAndSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:48: Error: Can't use 'duplicateStaticFieldAndSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:40: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//                                        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:9: Error: Can't use 'duplicateStaticFieldAndSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:48: Error: Can't use 'duplicateStaticFieldAndSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:40: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//                                        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:209:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
 //   Class.instanceFieldAndStaticSetter = c.instanceFieldAndStaticSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:9: Error: Can't use 'instanceFieldAndStaticDuplicateSetter' because it is declared more than once.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:9: Error: Can't use 'instanceFieldAndStaticDuplicateSetter' because it is declared more than once.
 //   Class.instanceFieldAndStaticDuplicateSetter =
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:47: Error: Can't assign to this.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:47: Error: Can't assign to this.
 //   Class.instanceFieldAndStaticDuplicateSetter =
 //                                               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:218:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter1;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:9: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndInstanceSetter1 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:220:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter1;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:48: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndInstanceSetter1 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:223:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter2;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:9: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndInstanceSetter2 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:225:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter2;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:48: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndInstanceSetter2 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   Class.duplicateInstanceFieldAndStaticSetter1 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:48: Error: Can't assign to this.
+//   Class.duplicateInstanceFieldAndStaticSetter1 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   Class.duplicateInstanceFieldAndStaticSetter2 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:48: Error: Can't assign to this.
+//   Class.duplicateInstanceFieldAndStaticSetter2 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:13: Error: Can't use 'duplicateExtensionStaticFieldAndSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:253:17: Error: Can't use 'duplicateExtensionStaticFieldAndSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:53: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndSetter1 =
+//                                                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:13: Error: Can't use 'duplicateExtensionStaticFieldAndSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:255:17: Error: Can't use 'duplicateExtensionStaticFieldAndSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:53: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndSetter2 =
+//                                                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:267:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
 //   Extension.extensionInstanceFieldAndStaticSetter =
 //             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:13: Error: Can't use 'extensionInstanceFieldAndStaticDuplicateSetter' because it is declared more than once.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:13: Error: Can't use 'extensionInstanceFieldAndStaticDuplicateSetter' because it is declared more than once.
 //   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
 //             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:60: Error: Can't assign to this.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:60: Error: Can't assign to this.
 //   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
 //                                                            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:121:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:13: Error: Can't use 'duplicateExtensionInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:13: Error: Can't use 'duplicateExtensionInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:13: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:288:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:290:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:13: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:293:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:295:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   c.duplicateInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:189:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//       c.duplicateInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:189:9: Error: The getter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+//       c.duplicateInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+//   c.duplicateInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   c.duplicateInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:191:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//       c.duplicateInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:191:9: Error: The getter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+//       c.duplicateInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+//   c.duplicateInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:201:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
 //  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceSetter'.
 //   c.staticFieldAndInstanceSetter = Class.staticFieldAndInstanceSetter;
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:204:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
 //  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceDuplicateSetter'.
 //   c.staticFieldAndInstanceDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:41: Error: The getter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:217:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter1'.
+//   c.duplicateStaticFieldAndInstanceSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:222:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter2'.
+//   c.duplicateStaticFieldAndInstanceSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:41: Error: The getter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndSetter'.
 //   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
 //                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndSetter'.
 //   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:9: Error: The getter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:234:9: Error: The getter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndDuplicateSetter'.
 //       0.extensionInstanceFieldAndDuplicateSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:233:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndDuplicateSetter'.
 //   0.extensionInstanceFieldAndDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:237:9: Error: The getter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+//       0.duplicateExtensionInstanceFieldAndSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:236:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+//   0.duplicateExtensionInstanceFieldAndSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:239:9: Error: The getter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+//       0.duplicateExtensionInstanceFieldAndSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:238:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+//   0.duplicateExtensionInstanceFieldAndSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:257:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceSetter'.
 //   0.extensionStaticFieldAndInstanceSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:158:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:262:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   0.extensionStaticFieldAndInstanceDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:166:9: Error: The getter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:270:9: Error: The getter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndStaticSetter'.
 //       0.extensionInstanceFieldAndStaticSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:269:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticSetter'.
 //   0.extensionInstanceFieldAndStaticSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:171:9: Error: The getter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:275:9: Error: The getter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //       0.extensionInstanceFieldAndStaticDuplicateSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:170:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:274:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   0.extensionInstanceFieldAndStaticDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:280:9: Error: The getter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//       0.duplicateExtensionInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:279:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   0.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:285:9: Error: The getter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//       0.duplicateExtensionInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:284:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   0.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:289:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   0.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:294:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   0.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:14: Error: Final field 'duplicateInstanceFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? duplicateInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:61:21: Error: Final field 'duplicateStaticFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   static final int? duplicateStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:14: Error: Final field 'duplicateInstanceFieldAndStaticSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? duplicateInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:98:21: Error: Final field 'duplicateStaticFieldAndInstanceSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   static final int? duplicateStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
 import self as self;
 import "dart:core" as core;
 
 class Class extends core::Object {
   field core::int? instanceFieldAndSetter = null;
   field core::int? instanceFieldAndDuplicateSetter = null;
+  field core::int? duplicateInstanceFieldAndSetter1 = null;
+  final field core::int? duplicateInstanceFieldAndSetter2 = null;
   late final [setter] field core::int? instanceLateFinalFieldAndSetter;
   late final [setter] field core::int? instanceLateFinalFieldAndDuplicateSetter;
   static field core::int? staticFieldAndSetter = null;
   static field core::int? staticFieldAndDuplicateSetter = null;
+  static field core::int? duplicateStaticFieldAndSetter1 = null;
+  static final field core::int? duplicateStaticFieldAndSetter2 = null;
   late static final [setter] field core::int? staticLateFinalFieldAndSetter;
   late static final [setter] field core::int? staticLateFinalFieldAndDuplicateSetter;
   static field core::int? staticFieldAndInstanceSetter = null;
   static field core::int? staticFieldAndInstanceDuplicateSetter = null;
   field core::int? instanceFieldAndStaticSetter = null;
   field core::int? instanceFieldAndStaticDuplicateSetter = null;
+  field core::int? duplicateInstanceFieldAndStaticSetter1 = null;
+  final field core::int? duplicateInstanceFieldAndStaticSetter2 = null;
+  static field core::int? duplicateStaticFieldAndInstanceSetter1 = null;
+  static final field core::int? duplicateStaticFieldAndInstanceSetter2 = null;
   synthetic constructor •() → self::Class
     : super core::Object::•()
     ;
@@ -486,100 +1102,204 @@
 extension Extension on core::int? {
   field extensionInstanceFieldAndSetter = self::Extension|extensionInstanceFieldAndSetter;
   field extensionInstanceFieldAndDuplicateSetter = self::Extension|extensionInstanceFieldAndDuplicateSetter;
+  field duplicateExtensionInstanceFieldAndSetter1 = self::Extension|duplicateExtensionInstanceFieldAndSetter1;
+  field duplicateExtensionInstanceFieldAndSetter2 = self::Extension|duplicateExtensionInstanceFieldAndSetter2;
   static field extensionStaticFieldAndSetter = self::Extension|extensionStaticFieldAndSetter;
   static field extensionStaticFieldAndDuplicateSetter = self::Extension|extensionStaticFieldAndDuplicateSetter;
+  static field duplicateExtensionStaticFieldAndSetter1 = self::Extension|duplicateExtensionStaticFieldAndSetter1;
+  static field duplicateExtensionStaticFieldAndSetter2 = self::Extension|duplicateExtensionStaticFieldAndSetter2;
   static field extensionStaticLateFinalFieldAndSetter = self::Extension|extensionStaticLateFinalFieldAndSetter;
   static field extensionStaticLateFinalFieldAndDuplicateSetter = self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
   static field extensionStaticFieldAndInstanceSetter = self::Extension|extensionStaticFieldAndInstanceSetter;
   static field extensionStaticFieldAndInstanceDuplicateSetter = self::Extension|extensionStaticFieldAndInstanceDuplicateSetter;
   field extensionInstanceFieldAndStaticSetter = self::Extension|extensionInstanceFieldAndStaticSetter;
   field extensionInstanceFieldAndStaticDuplicateSetter = self::Extension|extensionInstanceFieldAndStaticDuplicateSetter;
+  field duplicateExtensionInstanceFieldAndStaticSetter1 = self::Extension|duplicateExtensionInstanceFieldAndStaticSetter1;
+  field duplicateExtensionInstanceFieldAndStaticSetter2 = self::Extension|duplicateExtensionInstanceFieldAndStaticSetter2;
+  static field duplicateExtensionStaticFieldAndInstanceSetter1 = self::Extension|duplicateExtensionStaticFieldAndInstanceSetter1;
+  static field duplicateExtensionStaticFieldAndInstanceSetter2 = self::Extension|duplicateExtensionStaticFieldAndInstanceSetter2;
 }
 static field core::int? topLevelFieldAndSetter;
 static field core::int? topLevelFieldAndDuplicateSetter;
+static field core::int? duplicateTopLevelFieldAndSetter1;
+static final field core::int? duplicateTopLevelFieldAndSetter2;
 late static final [setter] field core::int? topLevelLateFinalFieldAndSetter;
 late static final [setter] field core::int? topLevelLateFinalFieldAndDuplicateSetter;
 static field core::int? Extension|extensionInstanceFieldAndSetter;
 static field core::int? Extension|extensionInstanceFieldAndDuplicateSetter;
+static field core::int? Extension|duplicateExtensionInstanceFieldAndSetter1;
+static final field core::int? Extension|duplicateExtensionInstanceFieldAndSetter2;
 static field core::int? Extension|extensionStaticFieldAndSetter;
 static field core::int? Extension|extensionStaticFieldAndDuplicateSetter;
+static field core::int? Extension|duplicateExtensionStaticFieldAndSetter1;
+static final field core::int? Extension|duplicateExtensionStaticFieldAndSetter2;
 late static final [setter] field core::int? Extension|extensionStaticLateFinalFieldAndSetter;
 late static final [setter] field core::int? Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
 static field core::int? Extension|extensionStaticFieldAndInstanceSetter;
 static field core::int? Extension|extensionStaticFieldAndInstanceDuplicateSetter;
 static field core::int? Extension|extensionInstanceFieldAndStaticSetter;
 static field core::int? Extension|extensionInstanceFieldAndStaticDuplicateSetter;
+static field core::int? Extension|duplicateExtensionInstanceFieldAndStaticSetter1;
+static final field core::int? Extension|duplicateExtensionInstanceFieldAndStaticSetter2;
+static field core::int? Extension|duplicateExtensionStaticFieldAndInstanceSetter1;
+static final field core::int? Extension|duplicateExtensionStaticFieldAndInstanceSetter2;
 static const field dynamic _exports# = #C1 /*isLegacy, from null */;
 static method test() → dynamic {
   self::topLevelFieldAndSetter = self::topLevelFieldAndSetter;
   self::topLevelFieldAndDuplicateSetter = self::topLevelFieldAndDuplicateSetter;
   self::topLevelLateFinalFieldAndSetter = self::topLevelLateFinalFieldAndSetter;
   self::topLevelLateFinalFieldAndDuplicateSetter = self::topLevelLateFinalFieldAndDuplicateSetter;
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:36: Error: Can't assign to this.
+  duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+                                   ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:36: Error: Can't assign to this.
+  duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+                                   ^";
   self::Class c = new self::Class::•();
   c.{self::Class::instanceFieldAndSetter} = c.{self::Class::instanceFieldAndSetter};
   c.{self::Class::instanceFieldAndDuplicateSetter} = c.{self::Class::instanceFieldAndDuplicateSetter};
   c.{self::Class::instanceLateFinalFieldAndSetter} = c.{self::Class::instanceLateFinalFieldAndSetter};
   c.{self::Class::instanceLateFinalFieldAndDuplicateSetter} = c.{self::Class::instanceLateFinalFieldAndDuplicateSetter};
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+  c.duplicateInstanceFieldAndStaticSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+  c.duplicateInstanceFieldAndStaticSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndSetter = self::Class::staticFieldAndSetter;
   self::Class::staticFieldAndDuplicateSetter = self::Class::staticFieldAndDuplicateSetter;
   self::Class::staticLateFinalFieldAndSetter = self::Class::staticLateFinalFieldAndSetter;
   self::Class::staticLateFinalFieldAndDuplicateSetter = self::Class::staticLateFinalFieldAndDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:121:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:40: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+                                       ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:40: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+                                       ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:201:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceSetter'.
   c.staticFieldAndInstanceSetter = Class.staticFieldAndInstanceSetter;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndInstanceSetter = self::Class::staticFieldAndInstanceSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:204:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceDuplicateSetter'.
   c.staticFieldAndInstanceDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndInstanceDuplicateSetter = self::Class::staticFieldAndInstanceDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:129:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:209:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
   Class.instanceFieldAndStaticSetter = c.instanceFieldAndStaticSetter;
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   c.{self::Class::instanceFieldAndStaticSetter} = c.{self::Class::instanceFieldAndStaticSetter};
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:47: Error: Can't assign to this.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:47: Error: Can't assign to this.
   Class.instanceFieldAndStaticDuplicateSetter =
                                               ^";
   c.{self::Class::instanceFieldAndStaticDuplicateSetter} = c.{self::Class::instanceFieldAndStaticDuplicateSetter};
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:217:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter1'.
+  c.duplicateStaticFieldAndInstanceSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:48: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndInstanceSetter1 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:222:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter2'.
+  c.duplicateStaticFieldAndInstanceSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:48: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndInstanceSetter2 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:48: Error: Can't assign to this.
+  Class.duplicateInstanceFieldAndStaticSetter1 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:48: Error: Can't assign to this.
+  Class.duplicateInstanceFieldAndStaticSetter2 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndSetter'.
   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:233:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndDuplicateSetter'.
   0.extensionInstanceFieldAndDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:236:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+  0.duplicateExtensionInstanceFieldAndSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:238:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+  0.duplicateExtensionInstanceFieldAndSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndSetter = self::Extension|extensionStaticFieldAndSetter;
   self::Extension|extensionStaticFieldAndDuplicateSetter = self::Extension|extensionStaticFieldAndDuplicateSetter;
   self::Extension|extensionStaticLateFinalFieldAndSetter = self::Extension|extensionStaticLateFinalFieldAndSetter;
   self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter = self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:53: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndSetter1 =
+                                                    ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:53: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndSetter2 =
+                                                    ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:257:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceSetter'.
   0.extensionStaticFieldAndInstanceSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndInstanceSetter = self::Extension|extensionStaticFieldAndInstanceSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:158:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:262:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceDuplicateSetter'.
   0.extensionStaticFieldAndInstanceDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndInstanceDuplicateSetter = self::Extension|extensionStaticFieldAndInstanceDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:267:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
   Extension.extensionInstanceFieldAndStaticSetter =
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:269:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticSetter'.
   0.extensionInstanceFieldAndStaticSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:60: Error: Can't assign to this.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:60: Error: Can't assign to this.
   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
                                                            ^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:170:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:274:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
   0.extensionInstanceFieldAndStaticDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:61: Error: Can't assign to this.
+  Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:279:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+  0.duplicateExtensionInstanceFieldAndStaticSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:61: Error: Can't assign to this.
+  Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:284:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+  0.duplicateExtensionInstanceFieldAndStaticSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:61: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:289:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+  0.duplicateExtensionStaticFieldAndInstanceSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:61: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:294:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+  0.duplicateExtensionStaticFieldAndInstanceSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.textual_outline.expect b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.textual_outline.expect
index 72d8b77..93febe8 100644
--- a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.textual_outline.expect
+++ b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.textual_outline.expect
@@ -3,6 +3,12 @@
 int? topLevelFieldAndDuplicateSetter;
 void set topLevelFieldAndDuplicateSetter(int? value) {}
 void set topLevelFieldAndDuplicateSetter(int? value) {}
+int? duplicateTopLevelFieldAndSetter1;
+final int? duplicateTopLevelFieldAndSetter1 = null;
+void set duplicateTopLevelFieldAndSetter1(int? value) {}
+final int? duplicateTopLevelFieldAndSetter2 = null;
+int? duplicateTopLevelFieldAndSetter2;
+void set duplicateTopLevelFieldAndSetter2(int? value) {}
 late
 final int? topLevelLateFinalFieldAndSetter;
 void set topLevelLateFinalFieldAndSetter(int? value) {}
@@ -16,6 +22,12 @@
   int? instanceFieldAndDuplicateSetter;
   void set instanceFieldAndDuplicateSetter(int? value) {}
   void set instanceFieldAndDuplicateSetter(int? value) {}
+  int? duplicateInstanceFieldAndSetter1;
+  final int? duplicateInstanceFieldAndSetter1 = null;
+  void set duplicateInstanceFieldAndSetter1(int? value) {}
+  final int? duplicateInstanceFieldAndSetter2 = null;
+  int? duplicateInstanceFieldAndSetter2;
+  void set duplicateInstanceFieldAndSetter2(int? value) {}
   late
   final int? instanceLateFinalFieldAndSetter;
   void set instanceLateFinalFieldAndSetter(int? value) {}
@@ -28,6 +40,12 @@
   static int? staticFieldAndDuplicateSetter;
   static void set staticFieldAndDuplicateSetter(int? value) {}
   static void set staticFieldAndDuplicateSetter(int? value) {}
+  static int? duplicateStaticFieldAndSetter1;
+  static final int? duplicateStaticFieldAndSetter1 = null;
+  static void set duplicateStaticFieldAndSetter1(int? value) {}
+  static final int? duplicateStaticFieldAndSetter2 = null;
+  static int? duplicateStaticFieldAndSetter2;
+  static void set duplicateStaticFieldAndSetter2(int? value) {}
   static late ;
   final int? staticLateFinalFieldAndSetter;
   static void set staticLateFinalFieldAndSetter(int? value) {}
@@ -45,6 +63,18 @@
   int? instanceFieldAndStaticDuplicateSetter;
   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+  int? duplicateInstanceFieldAndStaticSetter1;
+  final int? duplicateInstanceFieldAndStaticSetter1 = null;
+  static void set duplicateInstanceFieldAndStaticSetter1(int? value) {}
+  final int? duplicateInstanceFieldAndStaticSetter2 = null;
+  int? duplicateInstanceFieldAndStaticSetter2;
+  static void set duplicateInstanceFieldAndStaticSetter2(int? value) {}
+  static int? duplicateStaticFieldAndInstanceSetter1;
+  static final int? duplicateStaticFieldAndInstanceSetter1 = null;
+  void set duplicateStaticFieldAndInstanceSetter1(int? value) {}
+  static final int? duplicateStaticFieldAndInstanceSetter2 = null;
+  static int? duplicateStaticFieldAndInstanceSetter2;
+  void set duplicateStaticFieldAndInstanceSetter2(int? value) {}
 }
 extension Extension on int? {
   int? extensionInstanceFieldAndSetter;
@@ -52,11 +82,23 @@
   int? extensionInstanceFieldAndDuplicateSetter;
   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
+  int? duplicateExtensionInstanceFieldAndSetter1;
+  final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+  void set duplicateExtensionInstanceFieldAndSetter1(int? value) {}
+  final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+  int? duplicateExtensionInstanceFieldAndSetter2;
+  void set duplicateExtensionInstanceFieldAndSetter2(int? value) {}
   static int? extensionStaticFieldAndSetter;
   static void set extensionStaticFieldAndSetter(int? value) {}
   static int? extensionStaticFieldAndDuplicateSetter;
   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
+  static int? duplicateExtensionStaticFieldAndSetter1;
+  static final int? duplicateExtensionStaticFieldAndSetter1 = null;
+  static void set duplicateExtensionStaticFieldAndSetter1(int? value) {}
+  static final int? duplicateExtensionStaticFieldAndSetter2 = null;
+  static int? duplicateExtensionStaticFieldAndSetter2;
+  static void set duplicateExtensionStaticFieldAndSetter2(int? value) {}
   static late ;
   final int? extensionStaticLateFinalFieldAndSetter;
   static void set extensionStaticLateFinalFieldAndSetter(int? value) {}
@@ -74,6 +116,18 @@
   int? extensionInstanceFieldAndStaticDuplicateSetter;
   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+  int? duplicateExtensionInstanceFieldAndStaticSetter1;
+  final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+  static void set duplicateExtensionInstanceFieldAndStaticSetter1(int? value) {}
+  final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+  int? duplicateExtensionInstanceFieldAndStaticSetter2;
+  static void set duplicateExtensionInstanceFieldAndStaticSetter2(int? value) {}
+  static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+  static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+  void set duplicateExtensionStaticFieldAndInstanceSetter1(int? value) {}
+  static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+  static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+  void set duplicateExtensionStaticFieldAndInstanceSetter2(int? value) {}
 }
 test() {}
 main() {}
diff --git a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.weak.expect b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.weak.expect
index f523434..4827498 100644
--- a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.weak.expect
@@ -9,110 +9,276 @@
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:10: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:13:12: Error: 'duplicateTopLevelFieldAndSetter1' is already declared in this scope.
+// final int? duplicateTopLevelFieldAndSetter1 = null;
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:6: Context: Previous declaration of 'duplicateTopLevelFieldAndSetter1'.
+// int? duplicateTopLevelFieldAndSetter1;
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:6: Error: 'duplicateTopLevelFieldAndSetter2' is already declared in this scope.
+// int? duplicateTopLevelFieldAndSetter2;
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:12: Context: Previous declaration of 'duplicateTopLevelFieldAndSetter2'.
+// final int? duplicateTopLevelFieldAndSetter2 = null;
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:10: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:10: Context: Previous declaration of 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:10: Context: Previous declaration of 'topLevelLateFinalFieldAndDuplicateSetter'.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:12: Error: 'instanceFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:33:12: Error: 'instanceFieldAndDuplicateSetter' is already declared in this scope.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:12: Context: Previous declaration of 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Context: Previous declaration of 'instanceFieldAndDuplicateSetter'.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: 'instanceLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:36:14: Error: 'duplicateInstanceFieldAndSetter1' is already declared in this scope.
+//   final int? duplicateInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:8: Context: Previous declaration of 'duplicateInstanceFieldAndSetter1'.
+//   int? duplicateInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:40:8: Error: 'duplicateInstanceFieldAndSetter2' is already declared in this scope.
+//   int? duplicateInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:14: Context: Previous declaration of 'duplicateInstanceFieldAndSetter2'.
+//   final int? duplicateInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:12: Error: 'instanceLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:12: Context: Previous declaration of 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:47:12: Context: Previous declaration of 'instanceLateFinalFieldAndDuplicateSetter'.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:19: Error: 'staticFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:19: Error: 'staticFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:38:19: Context: Previous declaration of 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:54:19: Context: Previous declaration of 'staticFieldAndDuplicateSetter'.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: 'staticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:58:21: Error: 'duplicateStaticFieldAndSetter1' is already declared in this scope.
+//   static final int? duplicateStaticFieldAndSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:57:15: Context: Previous declaration of 'duplicateStaticFieldAndSetter1'.
+//   static int? duplicateStaticFieldAndSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:62:15: Error: 'duplicateStaticFieldAndSetter2' is already declared in this scope.
+//   static int? duplicateStaticFieldAndSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:61:21: Context: Previous declaration of 'duplicateStaticFieldAndSetter2'.
+//   static final int? duplicateStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:70:19: Error: 'staticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:45:19: Context: Previous declaration of 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:19: Context: Previous declaration of 'staticLateFinalFieldAndDuplicateSetter'.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:12: Error: 'staticFieldAndInstanceDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:77:12: Error: 'staticFieldAndInstanceDuplicateSetter' is already declared in this scope.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:52:12: Context: Previous declaration of 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:12: Context: Previous declaration of 'staticFieldAndInstanceDuplicateSetter'.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:60:19: Error: 'instanceFieldAndStaticDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:84:19: Error: 'instanceFieldAndStaticDuplicateSetter' is already declared in this scope.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Context: Previous declaration of 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Context: Previous declaration of 'instanceFieldAndStaticDuplicateSetter'.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:64:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:87:14: Error: 'duplicateInstanceFieldAndStaticSetter1' is already declared in this scope.
+//   final int? duplicateInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:8: Context: Previous declaration of 'duplicateInstanceFieldAndStaticSetter1'.
+//   int? duplicateInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:91:8: Error: 'duplicateInstanceFieldAndStaticSetter2' is already declared in this scope.
+//   int? duplicateInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:14: Context: Previous declaration of 'duplicateInstanceFieldAndStaticSetter2'.
+//   final int? duplicateInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:21: Error: 'duplicateStaticFieldAndInstanceSetter1' is already declared in this scope.
+//   static final int? duplicateStaticFieldAndInstanceSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:94:15: Context: Previous declaration of 'duplicateStaticFieldAndInstanceSetter1'.
+//   static int? duplicateStaticFieldAndInstanceSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:99:15: Error: 'duplicateStaticFieldAndInstanceSetter2' is already declared in this scope.
+//   static int? duplicateStaticFieldAndInstanceSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:98:21: Context: Previous declaration of 'duplicateStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:104:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:67:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:107:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndDuplicateSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:12: Error: 'extensionInstanceFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:109:12: Error: 'extensionInstanceFieldAndDuplicateSetter' is already declared in this scope.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:12: Context: Previous declaration of 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:108:12: Context: Previous declaration of 'extensionInstanceFieldAndDuplicateSetter'.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:19: Error: 'extensionStaticFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:112:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:112:14: Error: 'duplicateExtensionInstanceFieldAndSetter1' is already declared in this scope.
+//   final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndSetter1'.
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:115:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: 'duplicateExtensionInstanceFieldAndSetter2' is already declared in this scope.
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:115:14: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:19: Error: 'extensionStaticFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:19: Context: Previous declaration of 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:123:19: Context: Previous declaration of 'extensionStaticFieldAndDuplicateSetter'.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: 'extensionStaticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:127:21: Error: 'duplicateExtensionStaticFieldAndSetter1' is already declared in this scope.
+//   static final int? duplicateExtensionStaticFieldAndSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:126:15: Context: Previous declaration of 'duplicateExtensionStaticFieldAndSetter1'.
+//   static int? duplicateExtensionStaticFieldAndSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:131:15: Error: 'duplicateExtensionStaticFieldAndSetter2' is already declared in this scope.
+//   static int? duplicateExtensionStaticFieldAndSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:130:21: Context: Previous declaration of 'duplicateExtensionStaticFieldAndSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:19: Error: 'extensionStaticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:19: Context: Previous declaration of 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:19: Context: Previous declaration of 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:12: Error: 'extensionStaticFieldAndInstanceDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:146:12: Error: 'extensionStaticFieldAndInstanceDuplicateSetter' is already declared in this scope.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:89:12: Context: Previous declaration of 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:145:12: Context: Previous declaration of 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:148:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndStaticSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:151:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndStaticDuplicateSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:97:19: Error: 'extensionInstanceFieldAndStaticDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:19: Error: 'extensionInstanceFieldAndStaticDuplicateSetter' is already declared in this scope.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:19: Context: Previous declaration of 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:152:19: Context: Previous declaration of 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: 'duplicateExtensionInstanceFieldAndStaticSetter1' is already declared in this scope.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: 'duplicateExtensionInstanceFieldAndStaticSetter2' is already declared in this scope.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:164:21: Error: 'duplicateExtensionStaticFieldAndInstanceSetter1' is already declared in this scope.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:15: Context: Previous declaration of 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:15: Error: 'duplicateExtensionStaticFieldAndInstanceSetter2' is already declared in this scope.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:167:21: Context: Previous declaration of 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart: Error: 'topLevelFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 //
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
@@ -129,356 +295,806 @@
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:8:6: Error: Conflicts with setter 'topLevelFieldAndDuplicateSetter'.
-// int? topLevelFieldAndDuplicateSetter;
-//      ^
-//
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart:9:10: Error: Conflicts with the implicit setter of the field 'topLevelFieldAndDuplicateSetter'.
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:13:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:8:6: Error: Conflicts with setter 'topLevelFieldAndDuplicateSetter'.
+// int? topLevelFieldAndDuplicateSetter;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:14:10: Error: Conflicts with the implicit setter of the field 'duplicateTopLevelFieldAndSetter1'.
+// void set duplicateTopLevelFieldAndSetter1(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:6: Error: Conflicts with setter 'duplicateTopLevelFieldAndSetter1'.
+// int? duplicateTopLevelFieldAndSetter1;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:18:10: Error: Conflicts with the implicit setter of the field 'duplicateTopLevelFieldAndSetter2'.
+// void set duplicateTopLevelFieldAndSetter2(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:6: Error: Conflicts with setter 'duplicateTopLevelFieldAndSetter2'.
+// int? duplicateTopLevelFieldAndSetter2;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:21:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndSetter'.
 // void set topLevelLateFinalFieldAndSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:20:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndSetter'.
 // late final int? topLevelLateFinalFieldAndSetter;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:15:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
+// void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:23:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndDuplicateSetter'.
 // late final int? topLevelLateFinalFieldAndDuplicateSetter;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
-// void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
-//          ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:21:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:29:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndSetter'.
 //   void set instanceFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:20:8: Error: Conflicts with setter 'instanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:28:8: Error: Conflicts with setter 'instanceFieldAndSetter'.
 //   int? instanceFieldAndSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:33:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:23:8: Error: Conflicts with setter 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
+//   void set instanceFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:8: Error: Conflicts with setter 'instanceFieldAndDuplicateSetter'.
 //   int? instanceFieldAndDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
-//   void set instanceFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:37:12: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndSetter1'.
+//   void set duplicateInstanceFieldAndSetter1(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:28:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:8: Error: Conflicts with setter 'duplicateInstanceFieldAndSetter1'.
+//   int? duplicateInstanceFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:41:12: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndSetter2'.
+//   void set duplicateInstanceFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:40:8: Error: Conflicts with setter 'duplicateInstanceFieldAndSetter2'.
+//   int? duplicateInstanceFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:44:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndSetter'.
 //   void set instanceLateFinalFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:27:19: Error: Conflicts with setter 'instanceLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:43:19: Error: Conflicts with setter 'instanceLateFinalFieldAndSetter'.
 //   late final int? instanceLateFinalFieldAndSetter;
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:30:19: Error: Conflicts with setter 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:47:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
+//   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: Conflicts with setter 'instanceLateFinalFieldAndDuplicateSetter'.
 //   late final int? instanceLateFinalFieldAndDuplicateSetter;
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
-//   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:51:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndSetter'.
 //   static void set staticFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:34:15: Error: Conflicts with setter 'staticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:50:15: Error: Conflicts with setter 'staticFieldAndSetter'.
 //   static int? staticFieldAndSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:37:15: Error: Conflicts with setter 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:54:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
+//   static void set staticFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:15: Error: Conflicts with setter 'staticFieldAndDuplicateSetter'.
 //   static int? staticFieldAndDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:38:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
-//   static void set staticFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndSetter1'.
+//   static void set duplicateStaticFieldAndSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:42:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:57:15: Error: Conflicts with setter 'duplicateStaticFieldAndSetter1'.
+//   static int? duplicateStaticFieldAndSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:63:19: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndSetter2'.
+//   static void set duplicateStaticFieldAndSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:62:15: Error: Conflicts with setter 'duplicateStaticFieldAndSetter2'.
+//   static int? duplicateStaticFieldAndSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:66:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndSetter'.
 //   static void set staticLateFinalFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:41:26: Error: Conflicts with setter 'staticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:65:26: Error: Conflicts with setter 'staticLateFinalFieldAndSetter'.
 //   static late final int? staticLateFinalFieldAndSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:70:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:44:26: Error: Conflicts with setter 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
+//   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:26: Error: Conflicts with setter 'staticLateFinalFieldAndDuplicateSetter'.
 //   static late final int? staticLateFinalFieldAndDuplicateSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:45:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
-//   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
-//                   ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:49:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:73:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceSetter'.
 //   void set staticFieldAndInstanceSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:15: Error: Conflicts with setter 'staticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:72:15: Error: Conflicts with setter 'staticFieldAndInstanceSetter'.
 //   static int? staticFieldAndInstanceSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:77:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:51:15: Error: Conflicts with setter 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
+//   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:15: Error: Conflicts with setter 'staticFieldAndInstanceDuplicateSetter'.
 //   static int? staticFieldAndInstanceDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:52:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
-//   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:56:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:80:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticSetter'.
 //   static void set instanceFieldAndStaticSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:8: Error: Conflicts with setter 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:79:8: Error: Conflicts with setter 'instanceFieldAndStaticSetter'.
 //   int? instanceFieldAndStaticSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:60:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:84:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:58:8: Error: Conflicts with setter 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
+//   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:8: Error: Conflicts with setter 'instanceFieldAndStaticDuplicateSetter'.
 //   int? instanceFieldAndStaticDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
-//   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:88:19: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndStaticSetter1'.
+//   static void set duplicateInstanceFieldAndStaticSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:65:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:8: Error: Conflicts with setter 'duplicateInstanceFieldAndStaticSetter1'.
+//   int? duplicateInstanceFieldAndStaticSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:19: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndStaticSetter2'.
+//   static void set duplicateInstanceFieldAndStaticSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:91:8: Error: Conflicts with setter 'duplicateInstanceFieldAndStaticSetter2'.
+//   int? duplicateInstanceFieldAndStaticSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:12: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndInstanceSetter1'.
+//   void set duplicateStaticFieldAndInstanceSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:94:15: Error: Conflicts with setter 'duplicateStaticFieldAndInstanceSetter1'.
+//   static int? duplicateStaticFieldAndInstanceSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:100:12: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndInstanceSetter2'.
+//   void set duplicateStaticFieldAndInstanceSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:99:15: Error: Conflicts with setter 'duplicateStaticFieldAndInstanceSetter2'.
+//   static int? duplicateStaticFieldAndInstanceSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:105:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndSetter'.
 //   void set extensionInstanceFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:64:8: Error: Conflicts with setter 'extensionInstanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:104:8: Error: Conflicts with setter 'extensionInstanceFieldAndSetter'.
 //   int? extensionInstanceFieldAndSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:109:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:67:8: Error: Conflicts with setter 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:108:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
+//   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:107:8: Error: Conflicts with setter 'extensionInstanceFieldAndDuplicateSetter'.
 //   int? extensionInstanceFieldAndDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
-//   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:113:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndSetter1'.
+//   void set duplicateExtensionInstanceFieldAndSetter1(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:72:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndSetter1'.
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:117:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndSetter2'.
+//   void set duplicateExtensionInstanceFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndSetter2'.
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:120:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndSetter'.
 //   static void set extensionStaticFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:71:15: Error: Conflicts with setter 'extensionStaticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:119:15: Error: Conflicts with setter 'extensionStaticFieldAndSetter'.
 //   static int? extensionStaticFieldAndSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:74:15: Error: Conflicts with setter 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:123:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
+//   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:122:15: Error: Conflicts with setter 'extensionStaticFieldAndDuplicateSetter'.
 //   static int? extensionStaticFieldAndDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
-//   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:128:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndSetter1'.
+//   static void set duplicateExtensionStaticFieldAndSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:79:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:126:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndSetter1'.
+//   static int? duplicateExtensionStaticFieldAndSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndSetter2'.
+//   static void set duplicateExtensionStaticFieldAndSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:131:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndSetter2'.
+//   static int? duplicateExtensionStaticFieldAndSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:135:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndSetter'.
 //   static void set extensionStaticLateFinalFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:78:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:134:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndSetter'.
 //   static late final int? extensionStaticLateFinalFieldAndSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:81:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+//   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static late final int? extensionStaticLateFinalFieldAndDuplicateSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
-//   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
-//                   ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:142:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceSetter'.
 //   void set extensionStaticFieldAndInstanceSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:85:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:141:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceSetter'.
 //   static int? extensionStaticFieldAndInstanceSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:146:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:88:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:145:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
+//   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:144:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   static int? extensionStaticFieldAndInstanceDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:89:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
-//   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:93:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:149:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticSetter'.
 //   static void set extensionInstanceFieldAndStaticSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:148:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticSetter'.
 //   int? extensionInstanceFieldAndStaticSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:97:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:152:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
+//   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:151:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   int? extensionInstanceFieldAndStaticDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
-//   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:157:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   static void set duplicateExtensionInstanceFieldAndStaticSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:129:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:161:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   static void set duplicateExtensionInstanceFieldAndStaticSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   void set duplicateExtensionStaticFieldAndInstanceSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:164:21: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+//                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:169:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   void set duplicateExtensionStaticFieldAndInstanceSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:167:21: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+//                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:38: Error: Can't use 'duplicateTopLevelFieldAndSetter1' because it is declared more than once.
+//   duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+//                                      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:36: Error: Can't assign to this.
+//   duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:38: Error: Can't use 'duplicateTopLevelFieldAndSetter2' because it is declared more than once.
+//   duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+//                                      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:36: Error: Can't assign to this.
+//   duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:9: Error: Can't use 'duplicateStaticFieldAndSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:48: Error: Can't use 'duplicateStaticFieldAndSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:40: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//                                        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:9: Error: Can't use 'duplicateStaticFieldAndSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:48: Error: Can't use 'duplicateStaticFieldAndSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:40: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//                                        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:209:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
 //   Class.instanceFieldAndStaticSetter = c.instanceFieldAndStaticSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:9: Error: Can't use 'instanceFieldAndStaticDuplicateSetter' because it is declared more than once.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:9: Error: Can't use 'instanceFieldAndStaticDuplicateSetter' because it is declared more than once.
 //   Class.instanceFieldAndStaticDuplicateSetter =
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:47: Error: Can't assign to this.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:47: Error: Can't assign to this.
 //   Class.instanceFieldAndStaticDuplicateSetter =
 //                                               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:218:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter1;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:9: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndInstanceSetter1 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:220:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter1;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:48: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndInstanceSetter1 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:223:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter2;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:9: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndInstanceSetter2 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:225:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter2;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:48: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndInstanceSetter2 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   Class.duplicateInstanceFieldAndStaticSetter1 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:48: Error: Can't assign to this.
+//   Class.duplicateInstanceFieldAndStaticSetter1 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   Class.duplicateInstanceFieldAndStaticSetter2 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:48: Error: Can't assign to this.
+//   Class.duplicateInstanceFieldAndStaticSetter2 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:13: Error: Can't use 'duplicateExtensionStaticFieldAndSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:253:17: Error: Can't use 'duplicateExtensionStaticFieldAndSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:53: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndSetter1 =
+//                                                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:13: Error: Can't use 'duplicateExtensionStaticFieldAndSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:255:17: Error: Can't use 'duplicateExtensionStaticFieldAndSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:53: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndSetter2 =
+//                                                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:267:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
 //   Extension.extensionInstanceFieldAndStaticSetter =
 //             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:13: Error: Can't use 'extensionInstanceFieldAndStaticDuplicateSetter' because it is declared more than once.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:13: Error: Can't use 'extensionInstanceFieldAndStaticDuplicateSetter' because it is declared more than once.
 //   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
 //             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:60: Error: Can't assign to this.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:60: Error: Can't assign to this.
 //   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
 //                                                            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:121:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:13: Error: Can't use 'duplicateExtensionInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:13: Error: Can't use 'duplicateExtensionInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:13: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:288:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:290:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:13: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:293:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:295:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   c.duplicateInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:189:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//       c.duplicateInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:189:9: Error: The getter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+//       c.duplicateInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+//   c.duplicateInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   c.duplicateInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:191:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//       c.duplicateInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:191:9: Error: The getter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+//       c.duplicateInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+//   c.duplicateInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:201:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
 //  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceSetter'.
 //   c.staticFieldAndInstanceSetter = Class.staticFieldAndInstanceSetter;
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:204:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
 //  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceDuplicateSetter'.
 //   c.staticFieldAndInstanceDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:41: Error: The getter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:217:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter1'.
+//   c.duplicateStaticFieldAndInstanceSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:222:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter2'.
+//   c.duplicateStaticFieldAndInstanceSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:41: Error: The getter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndSetter'.
 //   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
 //                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndSetter'.
 //   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:9: Error: The getter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:234:9: Error: The getter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndDuplicateSetter'.
 //       0.extensionInstanceFieldAndDuplicateSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:233:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndDuplicateSetter'.
 //   0.extensionInstanceFieldAndDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:237:9: Error: The getter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+//       0.duplicateExtensionInstanceFieldAndSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:236:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+//   0.duplicateExtensionInstanceFieldAndSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:239:9: Error: The getter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+//       0.duplicateExtensionInstanceFieldAndSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:238:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+//   0.duplicateExtensionInstanceFieldAndSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:257:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceSetter'.
 //   0.extensionStaticFieldAndInstanceSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:158:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:262:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   0.extensionStaticFieldAndInstanceDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:166:9: Error: The getter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:270:9: Error: The getter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndStaticSetter'.
 //       0.extensionInstanceFieldAndStaticSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:269:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticSetter'.
 //   0.extensionInstanceFieldAndStaticSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:171:9: Error: The getter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:275:9: Error: The getter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //       0.extensionInstanceFieldAndStaticDuplicateSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:170:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:274:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   0.extensionInstanceFieldAndStaticDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:280:9: Error: The getter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//       0.duplicateExtensionInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:279:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   0.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:285:9: Error: The getter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//       0.duplicateExtensionInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:284:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   0.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:289:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   0.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:294:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   0.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:14: Error: Final field 'duplicateInstanceFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? duplicateInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:61:21: Error: Final field 'duplicateStaticFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   static final int? duplicateStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:14: Error: Final field 'duplicateInstanceFieldAndStaticSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? duplicateInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:98:21: Error: Final field 'duplicateStaticFieldAndInstanceSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   static final int? duplicateStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
 import self as self;
 import "dart:core" as core;
 
 class Class extends core::Object {
   field core::int? instanceFieldAndSetter = null;
   field core::int? instanceFieldAndDuplicateSetter = null;
+  field core::int? duplicateInstanceFieldAndSetter1 = null;
+  final field core::int? duplicateInstanceFieldAndSetter2 = null;
   late final [setter] field core::int? instanceLateFinalFieldAndSetter;
   late final [setter] field core::int? instanceLateFinalFieldAndDuplicateSetter;
   static field core::int? staticFieldAndSetter = null;
   static field core::int? staticFieldAndDuplicateSetter = null;
+  static field core::int? duplicateStaticFieldAndSetter1 = null;
+  static final field core::int? duplicateStaticFieldAndSetter2 = null;
   late static final [setter] field core::int? staticLateFinalFieldAndSetter;
   late static final [setter] field core::int? staticLateFinalFieldAndDuplicateSetter;
   static field core::int? staticFieldAndInstanceSetter = null;
   static field core::int? staticFieldAndInstanceDuplicateSetter = null;
   field core::int? instanceFieldAndStaticSetter = null;
   field core::int? instanceFieldAndStaticDuplicateSetter = null;
+  field core::int? duplicateInstanceFieldAndStaticSetter1 = null;
+  final field core::int? duplicateInstanceFieldAndStaticSetter2 = null;
+  static field core::int? duplicateStaticFieldAndInstanceSetter1 = null;
+  static final field core::int? duplicateStaticFieldAndInstanceSetter2 = null;
   synthetic constructor •() → self::Class
     : super core::Object::•()
     ;
@@ -486,100 +1102,204 @@
 extension Extension on core::int? {
   field extensionInstanceFieldAndSetter = self::Extension|extensionInstanceFieldAndSetter;
   field extensionInstanceFieldAndDuplicateSetter = self::Extension|extensionInstanceFieldAndDuplicateSetter;
+  field duplicateExtensionInstanceFieldAndSetter1 = self::Extension|duplicateExtensionInstanceFieldAndSetter1;
+  field duplicateExtensionInstanceFieldAndSetter2 = self::Extension|duplicateExtensionInstanceFieldAndSetter2;
   static field extensionStaticFieldAndSetter = self::Extension|extensionStaticFieldAndSetter;
   static field extensionStaticFieldAndDuplicateSetter = self::Extension|extensionStaticFieldAndDuplicateSetter;
+  static field duplicateExtensionStaticFieldAndSetter1 = self::Extension|duplicateExtensionStaticFieldAndSetter1;
+  static field duplicateExtensionStaticFieldAndSetter2 = self::Extension|duplicateExtensionStaticFieldAndSetter2;
   static field extensionStaticLateFinalFieldAndSetter = self::Extension|extensionStaticLateFinalFieldAndSetter;
   static field extensionStaticLateFinalFieldAndDuplicateSetter = self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
   static field extensionStaticFieldAndInstanceSetter = self::Extension|extensionStaticFieldAndInstanceSetter;
   static field extensionStaticFieldAndInstanceDuplicateSetter = self::Extension|extensionStaticFieldAndInstanceDuplicateSetter;
   field extensionInstanceFieldAndStaticSetter = self::Extension|extensionInstanceFieldAndStaticSetter;
   field extensionInstanceFieldAndStaticDuplicateSetter = self::Extension|extensionInstanceFieldAndStaticDuplicateSetter;
+  field duplicateExtensionInstanceFieldAndStaticSetter1 = self::Extension|duplicateExtensionInstanceFieldAndStaticSetter1;
+  field duplicateExtensionInstanceFieldAndStaticSetter2 = self::Extension|duplicateExtensionInstanceFieldAndStaticSetter2;
+  static field duplicateExtensionStaticFieldAndInstanceSetter1 = self::Extension|duplicateExtensionStaticFieldAndInstanceSetter1;
+  static field duplicateExtensionStaticFieldAndInstanceSetter2 = self::Extension|duplicateExtensionStaticFieldAndInstanceSetter2;
 }
 static field core::int? topLevelFieldAndSetter;
 static field core::int? topLevelFieldAndDuplicateSetter;
+static field core::int? duplicateTopLevelFieldAndSetter1;
+static final field core::int? duplicateTopLevelFieldAndSetter2;
 late static final [setter] field core::int? topLevelLateFinalFieldAndSetter;
 late static final [setter] field core::int? topLevelLateFinalFieldAndDuplicateSetter;
 static field core::int? Extension|extensionInstanceFieldAndSetter;
 static field core::int? Extension|extensionInstanceFieldAndDuplicateSetter;
+static field core::int? Extension|duplicateExtensionInstanceFieldAndSetter1;
+static final field core::int? Extension|duplicateExtensionInstanceFieldAndSetter2;
 static field core::int? Extension|extensionStaticFieldAndSetter;
 static field core::int? Extension|extensionStaticFieldAndDuplicateSetter;
+static field core::int? Extension|duplicateExtensionStaticFieldAndSetter1;
+static final field core::int? Extension|duplicateExtensionStaticFieldAndSetter2;
 late static final [setter] field core::int? Extension|extensionStaticLateFinalFieldAndSetter;
 late static final [setter] field core::int? Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
 static field core::int? Extension|extensionStaticFieldAndInstanceSetter;
 static field core::int? Extension|extensionStaticFieldAndInstanceDuplicateSetter;
 static field core::int? Extension|extensionInstanceFieldAndStaticSetter;
 static field core::int? Extension|extensionInstanceFieldAndStaticDuplicateSetter;
+static field core::int? Extension|duplicateExtensionInstanceFieldAndStaticSetter1;
+static final field core::int? Extension|duplicateExtensionInstanceFieldAndStaticSetter2;
+static field core::int? Extension|duplicateExtensionStaticFieldAndInstanceSetter1;
+static final field core::int? Extension|duplicateExtensionStaticFieldAndInstanceSetter2;
 static const field dynamic _exports# = #C1 /*isLegacy, from null */;
 static method test() → dynamic {
   self::topLevelFieldAndSetter = self::topLevelFieldAndSetter;
   self::topLevelFieldAndDuplicateSetter = self::topLevelFieldAndDuplicateSetter;
   self::topLevelLateFinalFieldAndSetter = self::topLevelLateFinalFieldAndSetter;
   self::topLevelLateFinalFieldAndDuplicateSetter = self::topLevelLateFinalFieldAndDuplicateSetter;
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:36: Error: Can't assign to this.
+  duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+                                   ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:36: Error: Can't assign to this.
+  duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+                                   ^";
   self::Class c = new self::Class::•();
   c.{self::Class::instanceFieldAndSetter} = c.{self::Class::instanceFieldAndSetter};
   c.{self::Class::instanceFieldAndDuplicateSetter} = c.{self::Class::instanceFieldAndDuplicateSetter};
   c.{self::Class::instanceLateFinalFieldAndSetter} = c.{self::Class::instanceLateFinalFieldAndSetter};
   c.{self::Class::instanceLateFinalFieldAndDuplicateSetter} = c.{self::Class::instanceLateFinalFieldAndDuplicateSetter};
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+  c.duplicateInstanceFieldAndStaticSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+  c.duplicateInstanceFieldAndStaticSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndSetter = self::Class::staticFieldAndSetter;
   self::Class::staticFieldAndDuplicateSetter = self::Class::staticFieldAndDuplicateSetter;
   self::Class::staticLateFinalFieldAndSetter = self::Class::staticLateFinalFieldAndSetter;
   self::Class::staticLateFinalFieldAndDuplicateSetter = self::Class::staticLateFinalFieldAndDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:121:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:40: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+                                       ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:40: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+                                       ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:201:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceSetter'.
   c.staticFieldAndInstanceSetter = Class.staticFieldAndInstanceSetter;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndInstanceSetter = self::Class::staticFieldAndInstanceSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:204:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceDuplicateSetter'.
   c.staticFieldAndInstanceDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndInstanceDuplicateSetter = self::Class::staticFieldAndInstanceDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:129:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:209:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
   Class.instanceFieldAndStaticSetter = c.instanceFieldAndStaticSetter;
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   c.{self::Class::instanceFieldAndStaticSetter} = c.{self::Class::instanceFieldAndStaticSetter};
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:47: Error: Can't assign to this.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:47: Error: Can't assign to this.
   Class.instanceFieldAndStaticDuplicateSetter =
                                               ^";
   c.{self::Class::instanceFieldAndStaticDuplicateSetter} = c.{self::Class::instanceFieldAndStaticDuplicateSetter};
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:217:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter1'.
+  c.duplicateStaticFieldAndInstanceSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:48: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndInstanceSetter1 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:222:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter2'.
+  c.duplicateStaticFieldAndInstanceSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:48: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndInstanceSetter2 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:48: Error: Can't assign to this.
+  Class.duplicateInstanceFieldAndStaticSetter1 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:48: Error: Can't assign to this.
+  Class.duplicateInstanceFieldAndStaticSetter2 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndSetter'.
   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:233:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndDuplicateSetter'.
   0.extensionInstanceFieldAndDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:236:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+  0.duplicateExtensionInstanceFieldAndSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:238:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+  0.duplicateExtensionInstanceFieldAndSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndSetter = self::Extension|extensionStaticFieldAndSetter;
   self::Extension|extensionStaticFieldAndDuplicateSetter = self::Extension|extensionStaticFieldAndDuplicateSetter;
   self::Extension|extensionStaticLateFinalFieldAndSetter = self::Extension|extensionStaticLateFinalFieldAndSetter;
   self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter = self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:53: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndSetter1 =
+                                                    ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:53: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndSetter2 =
+                                                    ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:257:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceSetter'.
   0.extensionStaticFieldAndInstanceSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndInstanceSetter = self::Extension|extensionStaticFieldAndInstanceSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:158:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:262:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceDuplicateSetter'.
   0.extensionStaticFieldAndInstanceDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndInstanceDuplicateSetter = self::Extension|extensionStaticFieldAndInstanceDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:267:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
   Extension.extensionInstanceFieldAndStaticSetter =
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:269:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticSetter'.
   0.extensionInstanceFieldAndStaticSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:60: Error: Can't assign to this.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:60: Error: Can't assign to this.
   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
                                                            ^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:170:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:274:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
   0.extensionInstanceFieldAndStaticDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:61: Error: Can't assign to this.
+  Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:279:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+  0.duplicateExtensionInstanceFieldAndStaticSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:61: Error: Can't assign to this.
+  Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:284:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+  0.duplicateExtensionInstanceFieldAndStaticSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:61: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:289:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+  0.duplicateExtensionStaticFieldAndInstanceSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:61: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:294:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+  0.duplicateExtensionStaticFieldAndInstanceSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.weak.transformed.expect
index f523434..4827498 100644
--- a/pkg/front_end/testcases/nnbd/field_vs_setter.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/field_vs_setter.dart.weak.transformed.expect
@@ -9,110 +9,276 @@
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:10: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:13:12: Error: 'duplicateTopLevelFieldAndSetter1' is already declared in this scope.
+// final int? duplicateTopLevelFieldAndSetter1 = null;
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:6: Context: Previous declaration of 'duplicateTopLevelFieldAndSetter1'.
+// int? duplicateTopLevelFieldAndSetter1;
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:6: Error: 'duplicateTopLevelFieldAndSetter2' is already declared in this scope.
+// int? duplicateTopLevelFieldAndSetter2;
+//      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:12: Context: Previous declaration of 'duplicateTopLevelFieldAndSetter2'.
+// final int? duplicateTopLevelFieldAndSetter2 = null;
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:10: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:10: Context: Previous declaration of 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:10: Context: Previous declaration of 'topLevelLateFinalFieldAndDuplicateSetter'.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:12: Error: 'instanceFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:33:12: Error: 'instanceFieldAndDuplicateSetter' is already declared in this scope.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:12: Context: Previous declaration of 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Context: Previous declaration of 'instanceFieldAndDuplicateSetter'.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: 'instanceLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:36:14: Error: 'duplicateInstanceFieldAndSetter1' is already declared in this scope.
+//   final int? duplicateInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:8: Context: Previous declaration of 'duplicateInstanceFieldAndSetter1'.
+//   int? duplicateInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:40:8: Error: 'duplicateInstanceFieldAndSetter2' is already declared in this scope.
+//   int? duplicateInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:14: Context: Previous declaration of 'duplicateInstanceFieldAndSetter2'.
+//   final int? duplicateInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:12: Error: 'instanceLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:12: Context: Previous declaration of 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:47:12: Context: Previous declaration of 'instanceLateFinalFieldAndDuplicateSetter'.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:19: Error: 'staticFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:19: Error: 'staticFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:38:19: Context: Previous declaration of 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:54:19: Context: Previous declaration of 'staticFieldAndDuplicateSetter'.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: 'staticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:58:21: Error: 'duplicateStaticFieldAndSetter1' is already declared in this scope.
+//   static final int? duplicateStaticFieldAndSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:57:15: Context: Previous declaration of 'duplicateStaticFieldAndSetter1'.
+//   static int? duplicateStaticFieldAndSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:62:15: Error: 'duplicateStaticFieldAndSetter2' is already declared in this scope.
+//   static int? duplicateStaticFieldAndSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:61:21: Context: Previous declaration of 'duplicateStaticFieldAndSetter2'.
+//   static final int? duplicateStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:70:19: Error: 'staticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:45:19: Context: Previous declaration of 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:19: Context: Previous declaration of 'staticLateFinalFieldAndDuplicateSetter'.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:12: Error: 'staticFieldAndInstanceDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:77:12: Error: 'staticFieldAndInstanceDuplicateSetter' is already declared in this scope.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:52:12: Context: Previous declaration of 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:12: Context: Previous declaration of 'staticFieldAndInstanceDuplicateSetter'.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:60:19: Error: 'instanceFieldAndStaticDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:84:19: Error: 'instanceFieldAndStaticDuplicateSetter' is already declared in this scope.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Context: Previous declaration of 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Context: Previous declaration of 'instanceFieldAndStaticDuplicateSetter'.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:64:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:87:14: Error: 'duplicateInstanceFieldAndStaticSetter1' is already declared in this scope.
+//   final int? duplicateInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:8: Context: Previous declaration of 'duplicateInstanceFieldAndStaticSetter1'.
+//   int? duplicateInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:91:8: Error: 'duplicateInstanceFieldAndStaticSetter2' is already declared in this scope.
+//   int? duplicateInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:14: Context: Previous declaration of 'duplicateInstanceFieldAndStaticSetter2'.
+//   final int? duplicateInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:21: Error: 'duplicateStaticFieldAndInstanceSetter1' is already declared in this scope.
+//   static final int? duplicateStaticFieldAndInstanceSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:94:15: Context: Previous declaration of 'duplicateStaticFieldAndInstanceSetter1'.
+//   static int? duplicateStaticFieldAndInstanceSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:99:15: Error: 'duplicateStaticFieldAndInstanceSetter2' is already declared in this scope.
+//   static int? duplicateStaticFieldAndInstanceSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:98:21: Context: Previous declaration of 'duplicateStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:104:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:67:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:107:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndDuplicateSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:12: Error: 'extensionInstanceFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:109:12: Error: 'extensionInstanceFieldAndDuplicateSetter' is already declared in this scope.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:12: Context: Previous declaration of 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:108:12: Context: Previous declaration of 'extensionInstanceFieldAndDuplicateSetter'.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:19: Error: 'extensionStaticFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:112:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:112:14: Error: 'duplicateExtensionInstanceFieldAndSetter1' is already declared in this scope.
+//   final int? duplicateExtensionInstanceFieldAndSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndSetter1'.
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:115:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: 'duplicateExtensionInstanceFieldAndSetter2' is already declared in this scope.
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:115:14: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:19: Error: 'extensionStaticFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:19: Context: Previous declaration of 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:123:19: Context: Previous declaration of 'extensionStaticFieldAndDuplicateSetter'.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: 'extensionStaticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:127:21: Error: 'duplicateExtensionStaticFieldAndSetter1' is already declared in this scope.
+//   static final int? duplicateExtensionStaticFieldAndSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:126:15: Context: Previous declaration of 'duplicateExtensionStaticFieldAndSetter1'.
+//   static int? duplicateExtensionStaticFieldAndSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:131:15: Error: 'duplicateExtensionStaticFieldAndSetter2' is already declared in this scope.
+//   static int? duplicateExtensionStaticFieldAndSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:130:21: Context: Previous declaration of 'duplicateExtensionStaticFieldAndSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:19: Error: 'extensionStaticLateFinalFieldAndDuplicateSetter' is already declared in this scope.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:19: Context: Previous declaration of 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:19: Context: Previous declaration of 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:12: Error: 'extensionStaticFieldAndInstanceDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:146:12: Error: 'extensionStaticFieldAndInstanceDuplicateSetter' is already declared in this scope.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:89:12: Context: Previous declaration of 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:145:12: Context: Previous declaration of 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:148:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndStaticSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:8: Error: Extensions can't declare instance fields
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:151:8: Error: Extensions can't declare instance fields
 // Try removing the field declaration or making it a static field
 //   int? extensionInstanceFieldAndStaticDuplicateSetter;
 //        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:97:19: Error: 'extensionInstanceFieldAndStaticDuplicateSetter' is already declared in this scope.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:19: Error: 'extensionInstanceFieldAndStaticDuplicateSetter' is already declared in this scope.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:19: Context: Previous declaration of 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:152:19: Context: Previous declaration of 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: 'duplicateExtensionInstanceFieldAndStaticSetter1' is already declared in this scope.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: Extensions can't declare instance fields
+// Try removing the field declaration or making it a static field
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: 'duplicateExtensionInstanceFieldAndStaticSetter2' is already declared in this scope.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Context: Previous declaration of 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:164:21: Error: 'duplicateExtensionStaticFieldAndInstanceSetter1' is already declared in this scope.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:15: Context: Previous declaration of 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:15: Error: 'duplicateExtensionStaticFieldAndInstanceSetter2' is already declared in this scope.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+//               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:167:21: Context: Previous declaration of 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart: Error: 'topLevelFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 //
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart: Error: 'topLevelLateFinalFieldAndDuplicateSetter' is exported from both 'pkg/front_end/testcases/nnbd/field_vs_setter.dart' and 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
@@ -129,356 +295,806 @@
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:8:6: Error: Conflicts with setter 'topLevelFieldAndDuplicateSetter'.
-// int? topLevelFieldAndDuplicateSetter;
-//      ^
-//
 // pkg/front_end/testcases/nnbd/field_vs_setter.dart:9:10: Error: Conflicts with the implicit setter of the field 'topLevelFieldAndDuplicateSetter'.
 // void set topLevelFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:13:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:8:6: Error: Conflicts with setter 'topLevelFieldAndDuplicateSetter'.
+// int? topLevelFieldAndDuplicateSetter;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:14:10: Error: Conflicts with the implicit setter of the field 'duplicateTopLevelFieldAndSetter1'.
+// void set duplicateTopLevelFieldAndSetter1(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:6: Error: Conflicts with setter 'duplicateTopLevelFieldAndSetter1'.
+// int? duplicateTopLevelFieldAndSetter1;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:18:10: Error: Conflicts with the implicit setter of the field 'duplicateTopLevelFieldAndSetter2'.
+// void set duplicateTopLevelFieldAndSetter2(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:6: Error: Conflicts with setter 'duplicateTopLevelFieldAndSetter2'.
+// int? duplicateTopLevelFieldAndSetter2;
+//      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:21:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndSetter'.
 // void set topLevelLateFinalFieldAndSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:12:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:20:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndSetter'.
 // late final int? topLevelLateFinalFieldAndSetter;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:17:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
 // void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:15:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
+// void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
+//          ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:23:17: Error: Conflicts with setter 'topLevelLateFinalFieldAndDuplicateSetter'.
 // late final int? topLevelLateFinalFieldAndDuplicateSetter;
 //                 ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:16:10: Error: Conflicts with the implicit setter of the field 'topLevelLateFinalFieldAndDuplicateSetter'.
-// void set topLevelLateFinalFieldAndDuplicateSetter(int? value) {}
-//          ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:21:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:29:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndSetter'.
 //   void set instanceFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:20:8: Error: Conflicts with setter 'instanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:28:8: Error: Conflicts with setter 'instanceFieldAndSetter'.
 //   int? instanceFieldAndSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:25:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:33:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
 //   void set instanceFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:23:8: Error: Conflicts with setter 'instanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
+//   void set instanceFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:8: Error: Conflicts with setter 'instanceFieldAndDuplicateSetter'.
 //   int? instanceFieldAndDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:24:12: Error: Conflicts with the implicit setter of the field 'instanceFieldAndDuplicateSetter'.
-//   void set instanceFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:37:12: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndSetter1'.
+//   void set duplicateInstanceFieldAndSetter1(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:28:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:8: Error: Conflicts with setter 'duplicateInstanceFieldAndSetter1'.
+//   int? duplicateInstanceFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:41:12: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndSetter2'.
+//   void set duplicateInstanceFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:40:8: Error: Conflicts with setter 'duplicateInstanceFieldAndSetter2'.
+//   int? duplicateInstanceFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:44:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndSetter'.
 //   void set instanceLateFinalFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:27:19: Error: Conflicts with setter 'instanceLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:43:19: Error: Conflicts with setter 'instanceLateFinalFieldAndSetter'.
 //   late final int? instanceLateFinalFieldAndSetter;
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:32:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
 //   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:30:19: Error: Conflicts with setter 'instanceLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:47:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
+//   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: Conflicts with setter 'instanceLateFinalFieldAndDuplicateSetter'.
 //   late final int? instanceLateFinalFieldAndDuplicateSetter;
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:31:12: Error: Conflicts with the implicit setter of the field 'instanceLateFinalFieldAndDuplicateSetter'.
-//   void set instanceLateFinalFieldAndDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:35:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:51:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndSetter'.
 //   static void set staticFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:34:15: Error: Conflicts with setter 'staticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:50:15: Error: Conflicts with setter 'staticFieldAndSetter'.
 //   static int? staticFieldAndSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
 //   static void set staticFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:37:15: Error: Conflicts with setter 'staticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:54:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
+//   static void set staticFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:15: Error: Conflicts with setter 'staticFieldAndDuplicateSetter'.
 //   static int? staticFieldAndDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:38:19: Error: Conflicts with the implicit setter of the field 'staticFieldAndDuplicateSetter'.
-//   static void set staticFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndSetter1'.
+//   static void set duplicateStaticFieldAndSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:42:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:57:15: Error: Conflicts with setter 'duplicateStaticFieldAndSetter1'.
+//   static int? duplicateStaticFieldAndSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:63:19: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndSetter2'.
+//   static void set duplicateStaticFieldAndSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:62:15: Error: Conflicts with setter 'duplicateStaticFieldAndSetter2'.
+//   static int? duplicateStaticFieldAndSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:66:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndSetter'.
 //   static void set staticLateFinalFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:41:26: Error: Conflicts with setter 'staticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:65:26: Error: Conflicts with setter 'staticLateFinalFieldAndSetter'.
 //   static late final int? staticLateFinalFieldAndSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:46:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:70:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
 //   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:44:26: Error: Conflicts with setter 'staticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
+//   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:26: Error: Conflicts with setter 'staticLateFinalFieldAndDuplicateSetter'.
 //   static late final int? staticLateFinalFieldAndDuplicateSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:45:19: Error: Conflicts with the implicit setter of the field 'staticLateFinalFieldAndDuplicateSetter'.
-//   static void set staticLateFinalFieldAndDuplicateSetter(int? value) {}
-//                   ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:49:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:73:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceSetter'.
 //   void set staticFieldAndInstanceSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:48:15: Error: Conflicts with setter 'staticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:72:15: Error: Conflicts with setter 'staticFieldAndInstanceSetter'.
 //   static int? staticFieldAndInstanceSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:53:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:77:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
 //   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:51:15: Error: Conflicts with setter 'staticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
+//   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:15: Error: Conflicts with setter 'staticFieldAndInstanceDuplicateSetter'.
 //   static int? staticFieldAndInstanceDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:52:12: Error: Conflicts with the implicit setter of the field 'staticFieldAndInstanceDuplicateSetter'.
-//   void set staticFieldAndInstanceDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:56:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:80:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticSetter'.
 //   static void set instanceFieldAndStaticSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:55:8: Error: Conflicts with setter 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:79:8: Error: Conflicts with setter 'instanceFieldAndStaticSetter'.
 //   int? instanceFieldAndStaticSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:60:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:84:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
 //   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:58:8: Error: Conflicts with setter 'instanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
+//   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:8: Error: Conflicts with setter 'instanceFieldAndStaticDuplicateSetter'.
 //   int? instanceFieldAndStaticDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:59:19: Error: Conflicts with the implicit setter of the field 'instanceFieldAndStaticDuplicateSetter'.
-//   static void set instanceFieldAndStaticDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:88:19: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndStaticSetter1'.
+//   static void set duplicateInstanceFieldAndStaticSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:65:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:8: Error: Conflicts with setter 'duplicateInstanceFieldAndStaticSetter1'.
+//   int? duplicateInstanceFieldAndStaticSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:19: Error: Conflicts with the implicit setter of the field 'duplicateInstanceFieldAndStaticSetter2'.
+//   static void set duplicateInstanceFieldAndStaticSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:91:8: Error: Conflicts with setter 'duplicateInstanceFieldAndStaticSetter2'.
+//   int? duplicateInstanceFieldAndStaticSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:12: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndInstanceSetter1'.
+//   void set duplicateStaticFieldAndInstanceSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:94:15: Error: Conflicts with setter 'duplicateStaticFieldAndInstanceSetter1'.
+//   static int? duplicateStaticFieldAndInstanceSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:100:12: Error: Conflicts with the implicit setter of the field 'duplicateStaticFieldAndInstanceSetter2'.
+//   void set duplicateStaticFieldAndInstanceSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:99:15: Error: Conflicts with setter 'duplicateStaticFieldAndInstanceSetter2'.
+//   static int? duplicateStaticFieldAndInstanceSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:105:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndSetter'.
 //   void set extensionInstanceFieldAndSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:64:8: Error: Conflicts with setter 'extensionInstanceFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:104:8: Error: Conflicts with setter 'extensionInstanceFieldAndSetter'.
 //   int? extensionInstanceFieldAndSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:69:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:109:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
 //   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:67:8: Error: Conflicts with setter 'extensionInstanceFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:108:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
+//   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:107:8: Error: Conflicts with setter 'extensionInstanceFieldAndDuplicateSetter'.
 //   int? extensionInstanceFieldAndDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:68:12: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndDuplicateSetter'.
-//   void set extensionInstanceFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:113:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndSetter1'.
+//   void set duplicateExtensionInstanceFieldAndSetter1(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:72:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:111:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndSetter1'.
+//   int? duplicateExtensionInstanceFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:117:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndSetter2'.
+//   void set duplicateExtensionInstanceFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:116:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndSetter2'.
+//   int? duplicateExtensionInstanceFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:120:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndSetter'.
 //   static void set extensionStaticFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:71:15: Error: Conflicts with setter 'extensionStaticFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:119:15: Error: Conflicts with setter 'extensionStaticFieldAndSetter'.
 //   static int? extensionStaticFieldAndSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:76:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
 //   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:74:15: Error: Conflicts with setter 'extensionStaticFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:123:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
+//   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:122:15: Error: Conflicts with setter 'extensionStaticFieldAndDuplicateSetter'.
 //   static int? extensionStaticFieldAndDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:75:19: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndDuplicateSetter'.
-//   static void set extensionStaticFieldAndDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:128:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndSetter1'.
+//   static void set duplicateExtensionStaticFieldAndSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:79:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:126:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndSetter1'.
+//   static int? duplicateExtensionStaticFieldAndSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndSetter2'.
+//   static void set duplicateExtensionStaticFieldAndSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:131:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndSetter2'.
+//   static int? duplicateExtensionStaticFieldAndSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:135:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndSetter'.
 //   static void set extensionStaticLateFinalFieldAndSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:78:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:134:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndSetter'.
 //   static late final int? extensionStaticLateFinalFieldAndSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:83:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:81:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
+//   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:26: Error: Conflicts with setter 'extensionStaticLateFinalFieldAndDuplicateSetter'.
 //   static late final int? extensionStaticLateFinalFieldAndDuplicateSetter;
 //                          ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:82:19: Error: Conflicts with the implicit setter of the field 'extensionStaticLateFinalFieldAndDuplicateSetter'.
-//   static void set extensionStaticLateFinalFieldAndDuplicateSetter(int? value) {}
-//                   ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:86:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:142:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceSetter'.
 //   void set extensionStaticFieldAndInstanceSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:85:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:141:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceSetter'.
 //   static int? extensionStaticFieldAndInstanceSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:146:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
 //            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:88:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:145:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
+//   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:144:15: Error: Conflicts with setter 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   static int? extensionStaticFieldAndInstanceDuplicateSetter;
 //               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:89:12: Error: Conflicts with the implicit setter of the field 'extensionStaticFieldAndInstanceDuplicateSetter'.
-//   void set extensionStaticFieldAndInstanceDuplicateSetter(int? value) {}
-//            ^
-//
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:93:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:149:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticSetter'.
 //   static void set extensionInstanceFieldAndStaticSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:92:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:148:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticSetter'.
 //   int? extensionInstanceFieldAndStaticSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:97:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:95:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticDuplicateSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:152:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
+//   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:151:8: Error: Conflicts with setter 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   int? extensionInstanceFieldAndStaticDuplicateSetter;
 //        ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:96:19: Error: Conflicts with the implicit setter of the field 'extensionInstanceFieldAndStaticDuplicateSetter'.
-//   static void set extensionInstanceFieldAndStaticDuplicateSetter(int? value) {}
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:157:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   static void set duplicateExtensionInstanceFieldAndStaticSetter1(int? value) {}
 //                   ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:129:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:155:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:156:14: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter1 = null;
+//              ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:161:19: Error: Conflicts with the implicit setter of the field 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   static void set duplicateExtensionInstanceFieldAndStaticSetter2(int? value) {}
+//                   ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:160:8: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   int? duplicateExtensionInstanceFieldAndStaticSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:159:14: Error: Conflicts with setter 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   final int? duplicateExtensionInstanceFieldAndStaticSetter2 = null;
+//              ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   void set duplicateExtensionStaticFieldAndInstanceSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter1;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:164:21: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter1 = null;
+//                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:169:12: Error: Conflicts with the implicit setter of the field 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   void set duplicateExtensionStaticFieldAndInstanceSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:15: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static int? duplicateExtensionStaticFieldAndInstanceSetter2;
+//               ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:167:21: Error: Conflicts with setter 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   static final int? duplicateExtensionStaticFieldAndInstanceSetter2 = null;
+//                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:38: Error: Can't use 'duplicateTopLevelFieldAndSetter1' because it is declared more than once.
+//   duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+//                                      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:36: Error: Can't assign to this.
+//   duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:38: Error: Can't use 'duplicateTopLevelFieldAndSetter2' because it is declared more than once.
+//   duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+//                                      ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:36: Error: Can't assign to this.
+//   duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+//                                    ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:9: Error: Can't use 'duplicateStaticFieldAndSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:48: Error: Can't use 'duplicateStaticFieldAndSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:40: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+//                                        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:9: Error: Can't use 'duplicateStaticFieldAndSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:48: Error: Can't use 'duplicateStaticFieldAndSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//                                                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:40: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+//                                        ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:209:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
 //   Class.instanceFieldAndStaticSetter = c.instanceFieldAndStaticSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:9: Error: Can't use 'instanceFieldAndStaticDuplicateSetter' because it is declared more than once.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:9: Error: Can't use 'instanceFieldAndStaticDuplicateSetter' because it is declared more than once.
 //   Class.instanceFieldAndStaticDuplicateSetter =
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:47: Error: Can't assign to this.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:47: Error: Can't assign to this.
 //   Class.instanceFieldAndStaticDuplicateSetter =
 //                                               ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:218:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter1;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:9: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//   Class.duplicateStaticFieldAndInstanceSetter1 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:220:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter1;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:48: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndInstanceSetter1 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:223:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter2;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:9: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//   Class.duplicateStaticFieldAndInstanceSetter2 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:225:13: Error: Can't use 'duplicateStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Class.duplicateStaticFieldAndInstanceSetter2;
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:48: Error: Can't assign to this.
+//   Class.duplicateStaticFieldAndInstanceSetter2 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   Class.duplicateInstanceFieldAndStaticSetter1 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:48: Error: Can't assign to this.
+//   Class.duplicateInstanceFieldAndStaticSetter1 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   Class.duplicateInstanceFieldAndStaticSetter2 =
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:48: Error: Can't assign to this.
+//   Class.duplicateInstanceFieldAndStaticSetter2 =
+//                                                ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:13: Error: Can't use 'duplicateExtensionStaticFieldAndSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:253:17: Error: Can't use 'duplicateExtensionStaticFieldAndSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:53: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndSetter1 =
+//                                                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:13: Error: Can't use 'duplicateExtensionStaticFieldAndSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:255:17: Error: Can't use 'duplicateExtensionStaticFieldAndSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:53: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndSetter2 =
+//                                                     ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:267:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
 //   Extension.extensionInstanceFieldAndStaticSetter =
 //             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:13: Error: Can't use 'extensionInstanceFieldAndStaticDuplicateSetter' because it is declared more than once.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:13: Error: Can't use 'extensionInstanceFieldAndStaticDuplicateSetter' because it is declared more than once.
 //   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
 //             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:60: Error: Can't assign to this.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:60: Error: Can't assign to this.
 //   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
 //                                                            ^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:121:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:13: Error: Can't use 'duplicateExtensionInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:13: Error: Can't use 'duplicateExtensionInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:13: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:288:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:290:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter1' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter1;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:13: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:293:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:61: Error: Can't assign to this.
+//   Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//                                                             ^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:295:17: Error: Can't use 'duplicateExtensionStaticFieldAndInstanceSetter2' because it is declared more than once.
+//       Extension.duplicateExtensionStaticFieldAndInstanceSetter2;
+//                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//   c.duplicateInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:189:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter1' because it is declared more than once.
+//       c.duplicateInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:189:9: Error: The getter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+//       c.duplicateInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+//   c.duplicateInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//   c.duplicateInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:191:9: Error: Can't use 'duplicateInstanceFieldAndStaticSetter2' because it is declared more than once.
+//       c.duplicateInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:191:9: Error: The getter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+//       c.duplicateInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+//   c.duplicateInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:201:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
 //  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceSetter'.
 //   c.staticFieldAndInstanceSetter = Class.staticFieldAndInstanceSetter;
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:204:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
 //  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceDuplicateSetter'.
 //   c.staticFieldAndInstanceDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:41: Error: The getter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:217:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter1'.
+//   c.duplicateStaticFieldAndInstanceSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:222:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter2'.
+//   c.duplicateStaticFieldAndInstanceSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:41: Error: The getter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndSetter'.
 //   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
 //                                         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndSetter'.
 //   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:139:9: Error: The getter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:234:9: Error: The getter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndDuplicateSetter'.
 //       0.extensionInstanceFieldAndDuplicateSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:233:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndDuplicateSetter'.
 //   0.extensionInstanceFieldAndDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:237:9: Error: The getter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+//       0.duplicateExtensionInstanceFieldAndSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:236:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+//   0.duplicateExtensionInstanceFieldAndSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:239:9: Error: The getter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+//       0.duplicateExtensionInstanceFieldAndSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:238:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+//   0.duplicateExtensionInstanceFieldAndSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:257:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceSetter'.
 //   0.extensionStaticFieldAndInstanceSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:158:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:262:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceDuplicateSetter'.
 //   0.extensionStaticFieldAndInstanceDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:166:9: Error: The getter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:270:9: Error: The getter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndStaticSetter'.
 //       0.extensionInstanceFieldAndStaticSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:269:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticSetter'.
 //   0.extensionInstanceFieldAndStaticSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:171:9: Error: The getter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:275:9: Error: The getter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing getter, or defining a getter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //       0.extensionInstanceFieldAndStaticDuplicateSetter;
 //         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
-// pkg/front_end/testcases/nnbd/field_vs_setter.dart:170:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:274:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 // Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
 //   0.extensionInstanceFieldAndStaticDuplicateSetter =
 //     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 //
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:280:9: Error: The getter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//       0.duplicateExtensionInstanceFieldAndStaticSetter1;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:279:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+//   0.duplicateExtensionInstanceFieldAndStaticSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:285:9: Error: The getter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//       0.duplicateExtensionInstanceFieldAndStaticSetter2;
+//         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:284:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+//   0.duplicateExtensionInstanceFieldAndStaticSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:289:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter1' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+//   0.duplicateExtensionStaticFieldAndInstanceSetter1 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:294:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter2' isn't defined for the class 'int'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+//   0.duplicateExtensionStaticFieldAndInstanceSetter2 =
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:39:14: Error: Final field 'duplicateInstanceFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? duplicateInstanceFieldAndSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:61:21: Error: Final field 'duplicateStaticFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   static final int? duplicateStaticFieldAndSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:90:14: Error: Final field 'duplicateInstanceFieldAndStaticSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? duplicateInstanceFieldAndStaticSetter2 = null;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/field_vs_setter.dart:98:21: Error: Final field 'duplicateStaticFieldAndInstanceSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   static final int? duplicateStaticFieldAndInstanceSetter2 = null;
+//                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
 import self as self;
 import "dart:core" as core;
 
 class Class extends core::Object {
   field core::int? instanceFieldAndSetter = null;
   field core::int? instanceFieldAndDuplicateSetter = null;
+  field core::int? duplicateInstanceFieldAndSetter1 = null;
+  final field core::int? duplicateInstanceFieldAndSetter2 = null;
   late final [setter] field core::int? instanceLateFinalFieldAndSetter;
   late final [setter] field core::int? instanceLateFinalFieldAndDuplicateSetter;
   static field core::int? staticFieldAndSetter = null;
   static field core::int? staticFieldAndDuplicateSetter = null;
+  static field core::int? duplicateStaticFieldAndSetter1 = null;
+  static final field core::int? duplicateStaticFieldAndSetter2 = null;
   late static final [setter] field core::int? staticLateFinalFieldAndSetter;
   late static final [setter] field core::int? staticLateFinalFieldAndDuplicateSetter;
   static field core::int? staticFieldAndInstanceSetter = null;
   static field core::int? staticFieldAndInstanceDuplicateSetter = null;
   field core::int? instanceFieldAndStaticSetter = null;
   field core::int? instanceFieldAndStaticDuplicateSetter = null;
+  field core::int? duplicateInstanceFieldAndStaticSetter1 = null;
+  final field core::int? duplicateInstanceFieldAndStaticSetter2 = null;
+  static field core::int? duplicateStaticFieldAndInstanceSetter1 = null;
+  static final field core::int? duplicateStaticFieldAndInstanceSetter2 = null;
   synthetic constructor •() → self::Class
     : super core::Object::•()
     ;
@@ -486,100 +1102,204 @@
 extension Extension on core::int? {
   field extensionInstanceFieldAndSetter = self::Extension|extensionInstanceFieldAndSetter;
   field extensionInstanceFieldAndDuplicateSetter = self::Extension|extensionInstanceFieldAndDuplicateSetter;
+  field duplicateExtensionInstanceFieldAndSetter1 = self::Extension|duplicateExtensionInstanceFieldAndSetter1;
+  field duplicateExtensionInstanceFieldAndSetter2 = self::Extension|duplicateExtensionInstanceFieldAndSetter2;
   static field extensionStaticFieldAndSetter = self::Extension|extensionStaticFieldAndSetter;
   static field extensionStaticFieldAndDuplicateSetter = self::Extension|extensionStaticFieldAndDuplicateSetter;
+  static field duplicateExtensionStaticFieldAndSetter1 = self::Extension|duplicateExtensionStaticFieldAndSetter1;
+  static field duplicateExtensionStaticFieldAndSetter2 = self::Extension|duplicateExtensionStaticFieldAndSetter2;
   static field extensionStaticLateFinalFieldAndSetter = self::Extension|extensionStaticLateFinalFieldAndSetter;
   static field extensionStaticLateFinalFieldAndDuplicateSetter = self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
   static field extensionStaticFieldAndInstanceSetter = self::Extension|extensionStaticFieldAndInstanceSetter;
   static field extensionStaticFieldAndInstanceDuplicateSetter = self::Extension|extensionStaticFieldAndInstanceDuplicateSetter;
   field extensionInstanceFieldAndStaticSetter = self::Extension|extensionInstanceFieldAndStaticSetter;
   field extensionInstanceFieldAndStaticDuplicateSetter = self::Extension|extensionInstanceFieldAndStaticDuplicateSetter;
+  field duplicateExtensionInstanceFieldAndStaticSetter1 = self::Extension|duplicateExtensionInstanceFieldAndStaticSetter1;
+  field duplicateExtensionInstanceFieldAndStaticSetter2 = self::Extension|duplicateExtensionInstanceFieldAndStaticSetter2;
+  static field duplicateExtensionStaticFieldAndInstanceSetter1 = self::Extension|duplicateExtensionStaticFieldAndInstanceSetter1;
+  static field duplicateExtensionStaticFieldAndInstanceSetter2 = self::Extension|duplicateExtensionStaticFieldAndInstanceSetter2;
 }
 static field core::int? topLevelFieldAndSetter;
 static field core::int? topLevelFieldAndDuplicateSetter;
+static field core::int? duplicateTopLevelFieldAndSetter1;
+static final field core::int? duplicateTopLevelFieldAndSetter2;
 late static final [setter] field core::int? topLevelLateFinalFieldAndSetter;
 late static final [setter] field core::int? topLevelLateFinalFieldAndDuplicateSetter;
 static field core::int? Extension|extensionInstanceFieldAndSetter;
 static field core::int? Extension|extensionInstanceFieldAndDuplicateSetter;
+static field core::int? Extension|duplicateExtensionInstanceFieldAndSetter1;
+static final field core::int? Extension|duplicateExtensionInstanceFieldAndSetter2;
 static field core::int? Extension|extensionStaticFieldAndSetter;
 static field core::int? Extension|extensionStaticFieldAndDuplicateSetter;
+static field core::int? Extension|duplicateExtensionStaticFieldAndSetter1;
+static final field core::int? Extension|duplicateExtensionStaticFieldAndSetter2;
 late static final [setter] field core::int? Extension|extensionStaticLateFinalFieldAndSetter;
 late static final [setter] field core::int? Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
 static field core::int? Extension|extensionStaticFieldAndInstanceSetter;
 static field core::int? Extension|extensionStaticFieldAndInstanceDuplicateSetter;
 static field core::int? Extension|extensionInstanceFieldAndStaticSetter;
 static field core::int? Extension|extensionInstanceFieldAndStaticDuplicateSetter;
+static field core::int? Extension|duplicateExtensionInstanceFieldAndStaticSetter1;
+static final field core::int? Extension|duplicateExtensionInstanceFieldAndStaticSetter2;
+static field core::int? Extension|duplicateExtensionStaticFieldAndInstanceSetter1;
+static final field core::int? Extension|duplicateExtensionStaticFieldAndInstanceSetter2;
 static const field dynamic _exports# = #C1 /*isLegacy, from null */;
 static method test() → dynamic {
   self::topLevelFieldAndSetter = self::topLevelFieldAndSetter;
   self::topLevelFieldAndDuplicateSetter = self::topLevelFieldAndDuplicateSetter;
   self::topLevelLateFinalFieldAndSetter = self::topLevelLateFinalFieldAndSetter;
   self::topLevelLateFinalFieldAndDuplicateSetter = self::topLevelLateFinalFieldAndDuplicateSetter;
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:178:36: Error: Can't assign to this.
+  duplicateTopLevelFieldAndSetter1 = duplicateTopLevelFieldAndSetter1;
+                                   ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:179:36: Error: Can't assign to this.
+  duplicateTopLevelFieldAndSetter2 = duplicateTopLevelFieldAndSetter2;
+                                   ^";
   self::Class c = new self::Class::•();
   c.{self::Class::instanceFieldAndSetter} = c.{self::Class::instanceFieldAndSetter};
   c.{self::Class::instanceFieldAndDuplicateSetter} = c.{self::Class::instanceFieldAndDuplicateSetter};
   c.{self::Class::instanceLateFinalFieldAndSetter} = c.{self::Class::instanceLateFinalFieldAndSetter};
   c.{self::Class::instanceLateFinalFieldAndDuplicateSetter} = c.{self::Class::instanceLateFinalFieldAndDuplicateSetter};
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:188:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter1'.
+  c.duplicateInstanceFieldAndStaticSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:190:5: Error: The setter 'duplicateInstanceFieldAndStaticSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateInstanceFieldAndStaticSetter2'.
+  c.duplicateInstanceFieldAndStaticSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndSetter = self::Class::staticFieldAndSetter;
   self::Class::staticFieldAndDuplicateSetter = self::Class::staticFieldAndDuplicateSetter;
   self::Class::staticLateFinalFieldAndSetter = self::Class::staticLateFinalFieldAndSetter;
   self::Class::staticLateFinalFieldAndDuplicateSetter = self::Class::staticLateFinalFieldAndDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:121:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:198:40: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndSetter1 = Class.duplicateStaticFieldAndSetter1;
+                                       ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:199:40: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndSetter2 = Class.duplicateStaticFieldAndSetter2;
+                                       ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:201:5: Error: The setter 'staticFieldAndInstanceSetter' isn't defined for the class 'Class'.
  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceSetter'.
   c.staticFieldAndInstanceSetter = Class.staticFieldAndInstanceSetter;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndInstanceSetter = self::Class::staticFieldAndInstanceSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:124:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:204:5: Error: The setter 'staticFieldAndInstanceDuplicateSetter' isn't defined for the class 'Class'.
  - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'staticFieldAndInstanceDuplicateSetter'.
   c.staticFieldAndInstanceDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Class::staticFieldAndInstanceDuplicateSetter = self::Class::staticFieldAndInstanceDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:129:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:209:9: Error: Setter not found: 'instanceFieldAndStaticSetter'.
   Class.instanceFieldAndStaticSetter = c.instanceFieldAndStaticSetter;
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   c.{self::Class::instanceFieldAndStaticSetter} = c.{self::Class::instanceFieldAndStaticSetter};
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:132:47: Error: Can't assign to this.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:212:47: Error: Can't assign to this.
   Class.instanceFieldAndStaticDuplicateSetter =
                                               ^";
   c.{self::Class::instanceFieldAndStaticDuplicateSetter} = c.{self::Class::instanceFieldAndStaticDuplicateSetter};
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:137:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:217:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter1'.
+  c.duplicateStaticFieldAndInstanceSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:219:48: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndInstanceSetter1 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:222:5: Error: The setter 'duplicateStaticFieldAndInstanceSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/field_vs_setter.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateStaticFieldAndInstanceSetter2'.
+  c.duplicateStaticFieldAndInstanceSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:224:48: Error: Can't assign to this.
+  Class.duplicateStaticFieldAndInstanceSetter2 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:227:48: Error: Can't assign to this.
+  Class.duplicateInstanceFieldAndStaticSetter1 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:229:48: Error: Can't assign to this.
+  Class.duplicateInstanceFieldAndStaticSetter2 =
+                                               ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:232:5: Error: The setter 'extensionInstanceFieldAndSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndSetter'.
   0.extensionInstanceFieldAndSetter = 0.extensionInstanceFieldAndSetter;
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:138:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:233:5: Error: The setter 'extensionInstanceFieldAndDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndDuplicateSetter'.
   0.extensionInstanceFieldAndDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:236:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter1'.
+  0.duplicateExtensionInstanceFieldAndSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:238:5: Error: The setter 'duplicateExtensionInstanceFieldAndSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndSetter2'.
+  0.duplicateExtensionInstanceFieldAndSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndSetter = self::Extension|extensionStaticFieldAndSetter;
   self::Extension|extensionStaticFieldAndDuplicateSetter = self::Extension|extensionStaticFieldAndDuplicateSetter;
   self::Extension|extensionStaticLateFinalFieldAndSetter = self::Extension|extensionStaticLateFinalFieldAndSetter;
   self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter = self::Extension|extensionStaticLateFinalFieldAndDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:153:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:252:53: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndSetter1 =
+                                                    ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:254:53: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndSetter2 =
+                                                    ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:257:5: Error: The setter 'extensionStaticFieldAndInstanceSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceSetter'.
   0.extensionStaticFieldAndInstanceSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndInstanceSetter = self::Extension|extensionStaticFieldAndInstanceSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:158:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:262:5: Error: The setter 'extensionStaticFieldAndInstanceDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionStaticFieldAndInstanceDuplicateSetter'.
   0.extensionStaticFieldAndInstanceDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
   self::Extension|extensionStaticFieldAndInstanceDuplicateSetter = self::Extension|extensionStaticFieldAndInstanceDuplicateSetter;
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:163:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:267:13: Error: Setter not found: 'extensionInstanceFieldAndStaticSetter'.
   Extension.extensionInstanceFieldAndStaticSetter =
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:165:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:269:5: Error: The setter 'extensionInstanceFieldAndStaticSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticSetter'.
   0.extensionInstanceFieldAndStaticSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:168:60: Error: Can't assign to this.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:272:60: Error: Can't assign to this.
   Extension.extensionInstanceFieldAndStaticDuplicateSetter =
                                                            ^";
-  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:170:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:274:5: Error: The setter 'extensionInstanceFieldAndStaticDuplicateSetter' isn't defined for the class 'int'.
 Try correcting the name to the name of an existing setter, or defining a setter or field named 'extensionInstanceFieldAndStaticDuplicateSetter'.
   0.extensionInstanceFieldAndStaticDuplicateSetter =
     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:277:61: Error: Can't assign to this.
+  Extension.duplicateExtensionInstanceFieldAndStaticSetter1 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:279:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter1'.
+  0.duplicateExtensionInstanceFieldAndStaticSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:282:61: Error: Can't assign to this.
+  Extension.duplicateExtensionInstanceFieldAndStaticSetter2 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:284:5: Error: The setter 'duplicateExtensionInstanceFieldAndStaticSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionInstanceFieldAndStaticSetter2'.
+  0.duplicateExtensionInstanceFieldAndStaticSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:287:61: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndInstanceSetter1 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:289:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter1' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter1'.
+  0.duplicateExtensionStaticFieldAndInstanceSetter1 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:292:61: Error: Can't assign to this.
+  Extension.duplicateExtensionStaticFieldAndInstanceSetter2 =
+                                                            ^";
+  invalid-expression "pkg/front_end/testcases/nnbd/field_vs_setter.dart:294:5: Error: The setter 'duplicateExtensionStaticFieldAndInstanceSetter2' isn't defined for the class 'int'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'duplicateExtensionStaticFieldAndInstanceSetter2'.
+  0.duplicateExtensionStaticFieldAndInstanceSetter2 =
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
 }
 static method main() → dynamic {}
 
diff --git a/pkg/front_end/testcases/nnbd/instance_duplicates.dart b/pkg/front_end/testcases/nnbd/instance_duplicates.dart
new file mode 100644
index 0000000..0fc9231
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/instance_duplicates.dart
@@ -0,0 +1,102 @@
+// Copyright (c) 2021, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+class Class {
+  int? methodAndField1() {}
+  int? methodAndField1;
+
+  int? methodAndField2;
+  int? methodAndField2() {}
+
+  int? methodAndFinalField1() {}
+  final int? methodAndFinalField1 = 0;
+
+  final int? methodAndFinalField2 = 0;
+  int? methodAndFinalField2() {}
+
+  int? methodAndFieldAndSetter1() {}
+  int? methodAndFieldAndSetter1;
+  void set methodAndFieldAndSetter1(int? value) {}
+
+  int? methodAndFieldAndSetter2;
+  int? methodAndFieldAndSetter2() {}
+  void set methodAndFieldAndSetter2(int? value) {}
+
+  void set methodAndFieldAndSetter3(int? value) {}
+  int? methodAndFieldAndSetter3() {}
+  int? methodAndFieldAndSetter3;
+
+  void set methodAndFieldAndSetter4(int? value) {}
+  int? methodAndFieldAndSetter4;
+  int? methodAndFieldAndSetter4() {}
+
+  int? methodAndFinalFieldAndSetter1() {}
+  final int? methodAndFinalFieldAndSetter1 = 0;
+  void set methodAndFinalFieldAndSetter1(int? value) {}
+
+  final int? methodAndFinalFieldAndSetter2 = 0;
+  int? methodAndFinalFieldAndSetter2() {}
+  void set methodAndFinalFieldAndSetter2(int? value) {}
+
+  void set methodAndFinalFieldAndSetter3(int? value) {}
+  int? methodAndFinalFieldAndSetter3() {}
+  final int? methodAndFinalFieldAndSetter3 = 0;
+
+  void set methodAndFinalFieldAndSetter4(int? value) {}
+  final int? methodAndFinalFieldAndSetter4 = 0;
+  int? methodAndFinalFieldAndSetter4() {}
+
+  int? methodAndSetter1() {}
+  void set methodAndSetter1(int? value) {}
+
+  void methodAndSetter2(int? value) {}
+  int? set methodAndSetter2() {}
+
+  int? fieldAndSetter1;
+  void set fieldAndSetter1(int? value) {}
+
+  int? fieldAndSetter2;
+  void set fieldAndSetter2(int? value) {}
+
+  int? fieldAndFinalFieldAndSetter1;
+  final int? fieldAndFinalFieldAndSetter1 = 0;
+  void set fieldAndFinalFieldAndSetter1(int? value) {}
+
+  final int? fieldAndFinalFieldAndSetter2 = 0;
+  int? fieldAndFinalFieldAndSetter2;
+  void set fieldAndFinalFieldAndSetter2(int? value) {}
+
+  void set fieldAndFinalFieldAndSetter3(int? value) {}
+  int? fieldAndFinalFieldAndSetter3;
+  final int? fieldAndFinalFieldAndSetter3 = 0;
+
+  void set fieldAndFinalFieldAndSetter4(int? value) {}
+  final int? fieldAndFinalFieldAndSetter4 = 0;
+  int? fieldAndFinalFieldAndSetter4;
+}
+
+test(Class c) {
+  c.methodAndField1 = c.methodAndField1;
+  c.methodAndField2 = c.methodAndField2;
+  c.methodAndFinalField1;
+  c.methodAndFinalField2;
+  c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+  c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+  c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+  c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+  c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+  c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+  c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+  c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+  c.methodAndSetter1 = c.methodAndSetter1;
+  c.methodAndSetter2 = c.methodAndSetter2;
+  c.fieldAndSetter1 = c.fieldAndSetter1;
+  c.fieldAndSetter2 = c.fieldAndSetter2;
+  c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+  c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+  c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+  c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+}
+
+main() {}
diff --git a/pkg/front_end/testcases/nnbd/instance_duplicates.dart.outline.expect b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.outline.expect
new file mode 100644
index 0000000..e927ed8
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.outline.expect
@@ -0,0 +1,273 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:7:8: Error: 'methodAndField1' is already declared in this scope.
+//   int? methodAndField1;
+//        ^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:6:8: Context: Previous declaration of 'methodAndField1'.
+//   int? methodAndField1() {}
+//        ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:10:8: Error: 'methodAndField2' is already declared in this scope.
+//   int? methodAndField2() {}
+//        ^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:9:8: Context: Previous declaration of 'methodAndField2'.
+//   int? methodAndField2;
+//        ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:13:14: Error: 'methodAndFinalField1' is already declared in this scope.
+//   final int? methodAndFinalField1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:12:8: Context: Previous declaration of 'methodAndFinalField1'.
+//   int? methodAndFinalField1() {}
+//        ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:16:8: Error: 'methodAndFinalField2' is already declared in this scope.
+//   int? methodAndFinalField2() {}
+//        ^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:15:14: Context: Previous declaration of 'methodAndFinalField2'.
+//   final int? methodAndFinalField2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:19:8: Error: 'methodAndFieldAndSetter1' is already declared in this scope.
+//   int? methodAndFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:18:8: Context: Previous declaration of 'methodAndFieldAndSetter1'.
+//   int? methodAndFieldAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:23:8: Error: 'methodAndFieldAndSetter2' is already declared in this scope.
+//   int? methodAndFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:22:8: Context: Previous declaration of 'methodAndFieldAndSetter2'.
+//   int? methodAndFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:28:8: Error: 'methodAndFieldAndSetter3' is already declared in this scope.
+//   int? methodAndFieldAndSetter3;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:27:8: Context: Previous declaration of 'methodAndFieldAndSetter3'.
+//   int? methodAndFieldAndSetter3() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:32:8: Error: 'methodAndFieldAndSetter4' is already declared in this scope.
+//   int? methodAndFieldAndSetter4() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:31:8: Context: Previous declaration of 'methodAndFieldAndSetter4'.
+//   int? methodAndFieldAndSetter4;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:35:14: Error: 'methodAndFinalFieldAndSetter1' is already declared in this scope.
+//   final int? methodAndFinalFieldAndSetter1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:34:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter1'.
+//   int? methodAndFinalFieldAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:39:8: Error: 'methodAndFinalFieldAndSetter2' is already declared in this scope.
+//   int? methodAndFinalFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:38:14: Context: Previous declaration of 'methodAndFinalFieldAndSetter2'.
+//   final int? methodAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:44:14: Error: 'methodAndFinalFieldAndSetter3' is already declared in this scope.
+//   final int? methodAndFinalFieldAndSetter3 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:43:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter3'.
+//   int? methodAndFinalFieldAndSetter3() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:48:8: Error: 'methodAndFinalFieldAndSetter4' is already declared in this scope.
+//   int? methodAndFinalFieldAndSetter4() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:47:14: Context: Previous declaration of 'methodAndFinalFieldAndSetter4'.
+//   final int? methodAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:3: Error: The return type of the setter must be 'void' or absent.
+// Try removing the return type, or define a method rather than a setter.
+//   int? set methodAndSetter2() {}
+//   ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:63:14: Error: 'fieldAndFinalFieldAndSetter1' is already declared in this scope.
+//   final int? fieldAndFinalFieldAndSetter1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:62:8: Context: Previous declaration of 'fieldAndFinalFieldAndSetter1'.
+//   int? fieldAndFinalFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:67:8: Error: 'fieldAndFinalFieldAndSetter2' is already declared in this scope.
+//   int? fieldAndFinalFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:66:14: Context: Previous declaration of 'fieldAndFinalFieldAndSetter2'.
+//   final int? fieldAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:72:14: Error: 'fieldAndFinalFieldAndSetter3' is already declared in this scope.
+//   final int? fieldAndFinalFieldAndSetter3 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:71:8: Context: Previous declaration of 'fieldAndFinalFieldAndSetter3'.
+//   int? fieldAndFinalFieldAndSetter3;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:76:8: Error: 'fieldAndFinalFieldAndSetter4' is already declared in this scope.
+//   int? fieldAndFinalFieldAndSetter4;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:75:14: Context: Previous declaration of 'fieldAndFinalFieldAndSetter4'.
+//   final int? fieldAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:20:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter1'.
+//   void set methodAndFieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:19:8: Error: Conflicts with setter 'methodAndFieldAndSetter1'.
+//   int? methodAndFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:24:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter2'.
+//   void set methodAndFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:22:8: Error: Conflicts with setter 'methodAndFieldAndSetter2'.
+//   int? methodAndFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:26:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter3'.
+//   void set methodAndFieldAndSetter3(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:28:8: Error: Conflicts with setter 'methodAndFieldAndSetter3'.
+//   int? methodAndFieldAndSetter3;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:30:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter4'.
+//   void set methodAndFieldAndSetter4(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:31:8: Error: Conflicts with setter 'methodAndFieldAndSetter4'.
+//   int? methodAndFieldAndSetter4;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:57:12: Error: Conflicts with the implicit setter of the field 'fieldAndSetter1'.
+//   void set fieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:56:8: Error: Conflicts with setter 'fieldAndSetter1'.
+//   int? fieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:60:12: Error: Conflicts with the implicit setter of the field 'fieldAndSetter2'.
+//   void set fieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:59:8: Error: Conflicts with setter 'fieldAndSetter2'.
+//   int? fieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:64:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter1'.
+//   void set fieldAndFinalFieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:62:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter1'.
+//   int? fieldAndFinalFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:68:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter2'.
+//   void set fieldAndFinalFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:67:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter2'.
+//   int? fieldAndFinalFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:70:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter3'.
+//   void set fieldAndFinalFieldAndSetter3(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:71:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter3'.
+//   int? fieldAndFinalFieldAndSetter3;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:74:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter4'.
+//   void set fieldAndFinalFieldAndSetter4(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:76:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter4'.
+//   int? fieldAndFinalFieldAndSetter4;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:40:12: Error: 'methodAndFinalFieldAndSetter2' is already declared in this scope.
+//   void set methodAndFinalFieldAndSetter2(int? value) {}
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:39:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter2'.
+//   int? methodAndFinalFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:51:12: Error: 'methodAndSetter1' is already declared in this scope.
+//   void set methodAndSetter1(int? value) {}
+//            ^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:50:8: Context: Previous declaration of 'methodAndSetter1'.
+//   int? methodAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:12: Error: 'methodAndSetter2' is already declared in this scope.
+//   int? set methodAndSetter2() {}
+//            ^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:53:8: Context: Previous declaration of 'methodAndSetter2'.
+//   void methodAndSetter2(int? value) {}
+//        ^^^^^^^^^^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Class extends core::Object {
+  field core::int? methodAndField2;
+  final field core::int? methodAndFinalField2;
+  field core::int? methodAndFieldAndSetter2;
+  field core::int? methodAndFieldAndSetter4;
+  final field core::int? methodAndFinalFieldAndSetter2;
+  final field core::int? methodAndFinalFieldAndSetter4;
+  field core::int? fieldAndSetter1;
+  field core::int? fieldAndSetter2;
+  field core::int? fieldAndFinalFieldAndSetter1;
+  final field core::int? fieldAndFinalFieldAndSetter2;
+  field core::int? fieldAndFinalFieldAndSetter3;
+  final field core::int? fieldAndFinalFieldAndSetter4;
+  synthetic constructor •() → self::Class
+    ;
+  method methodAndField1() → core::int?
+    ;
+  method methodAndFinalField1() → core::int?
+    ;
+  method methodAndFieldAndSetter1() → core::int?
+    ;
+  method methodAndFieldAndSetter3() → core::int?
+    ;
+  method methodAndFinalFieldAndSetter1() → core::int?
+    ;
+  set methodAndFinalFieldAndSetter1(core::int? value) → void
+    ;
+  set methodAndFinalFieldAndSetter2(core::int? value) → void
+    ;
+  set methodAndFinalFieldAndSetter3(core::int? value) → void
+    ;
+  method methodAndFinalFieldAndSetter3() → core::int?
+    ;
+  set methodAndFinalFieldAndSetter4(core::int? value) → void
+    ;
+  method methodAndSetter1() → core::int?
+    ;
+  set methodAndSetter1(core::int? value) → void
+    ;
+  method methodAndSetter2(core::int? value) → void
+    ;
+  set methodAndSetter2(dynamic #synthetic) → void
+    ;
+}
+static method test(self::Class c) → dynamic
+  ;
+static method main() → dynamic
+  ;
diff --git a/pkg/front_end/testcases/nnbd/instance_duplicates.dart.strong.expect b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.strong.expect
new file mode 100644
index 0000000..8687a05
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.strong.expect
@@ -0,0 +1,628 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:7:8: Error: 'methodAndField1' is already declared in this scope.
+//   int? methodAndField1;
+//        ^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:6:8: Context: Previous declaration of 'methodAndField1'.
+//   int? methodAndField1() {}
+//        ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:10:8: Error: 'methodAndField2' is already declared in this scope.
+//   int? methodAndField2() {}
+//        ^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:9:8: Context: Previous declaration of 'methodAndField2'.
+//   int? methodAndField2;
+//        ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:13:14: Error: 'methodAndFinalField1' is already declared in this scope.
+//   final int? methodAndFinalField1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:12:8: Context: Previous declaration of 'methodAndFinalField1'.
+//   int? methodAndFinalField1() {}
+//        ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:16:8: Error: 'methodAndFinalField2' is already declared in this scope.
+//   int? methodAndFinalField2() {}
+//        ^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:15:14: Context: Previous declaration of 'methodAndFinalField2'.
+//   final int? methodAndFinalField2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:19:8: Error: 'methodAndFieldAndSetter1' is already declared in this scope.
+//   int? methodAndFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:18:8: Context: Previous declaration of 'methodAndFieldAndSetter1'.
+//   int? methodAndFieldAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:23:8: Error: 'methodAndFieldAndSetter2' is already declared in this scope.
+//   int? methodAndFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:22:8: Context: Previous declaration of 'methodAndFieldAndSetter2'.
+//   int? methodAndFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:28:8: Error: 'methodAndFieldAndSetter3' is already declared in this scope.
+//   int? methodAndFieldAndSetter3;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:27:8: Context: Previous declaration of 'methodAndFieldAndSetter3'.
+//   int? methodAndFieldAndSetter3() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:32:8: Error: 'methodAndFieldAndSetter4' is already declared in this scope.
+//   int? methodAndFieldAndSetter4() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:31:8: Context: Previous declaration of 'methodAndFieldAndSetter4'.
+//   int? methodAndFieldAndSetter4;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:35:14: Error: 'methodAndFinalFieldAndSetter1' is already declared in this scope.
+//   final int? methodAndFinalFieldAndSetter1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:34:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter1'.
+//   int? methodAndFinalFieldAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:39:8: Error: 'methodAndFinalFieldAndSetter2' is already declared in this scope.
+//   int? methodAndFinalFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:38:14: Context: Previous declaration of 'methodAndFinalFieldAndSetter2'.
+//   final int? methodAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:44:14: Error: 'methodAndFinalFieldAndSetter3' is already declared in this scope.
+//   final int? methodAndFinalFieldAndSetter3 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:43:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter3'.
+//   int? methodAndFinalFieldAndSetter3() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:48:8: Error: 'methodAndFinalFieldAndSetter4' is already declared in this scope.
+//   int? methodAndFinalFieldAndSetter4() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:47:14: Context: Previous declaration of 'methodAndFinalFieldAndSetter4'.
+//   final int? methodAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:3: Error: The return type of the setter must be 'void' or absent.
+// Try removing the return type, or define a method rather than a setter.
+//   int? set methodAndSetter2() {}
+//   ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:63:14: Error: 'fieldAndFinalFieldAndSetter1' is already declared in this scope.
+//   final int? fieldAndFinalFieldAndSetter1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:62:8: Context: Previous declaration of 'fieldAndFinalFieldAndSetter1'.
+//   int? fieldAndFinalFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:67:8: Error: 'fieldAndFinalFieldAndSetter2' is already declared in this scope.
+//   int? fieldAndFinalFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:66:14: Context: Previous declaration of 'fieldAndFinalFieldAndSetter2'.
+//   final int? fieldAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:72:14: Error: 'fieldAndFinalFieldAndSetter3' is already declared in this scope.
+//   final int? fieldAndFinalFieldAndSetter3 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:71:8: Context: Previous declaration of 'fieldAndFinalFieldAndSetter3'.
+//   int? fieldAndFinalFieldAndSetter3;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:76:8: Error: 'fieldAndFinalFieldAndSetter4' is already declared in this scope.
+//   int? fieldAndFinalFieldAndSetter4;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:75:14: Context: Previous declaration of 'fieldAndFinalFieldAndSetter4'.
+//   final int? fieldAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:20:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter1'.
+//   void set methodAndFieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:19:8: Error: Conflicts with setter 'methodAndFieldAndSetter1'.
+//   int? methodAndFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:24:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter2'.
+//   void set methodAndFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:22:8: Error: Conflicts with setter 'methodAndFieldAndSetter2'.
+//   int? methodAndFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:26:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter3'.
+//   void set methodAndFieldAndSetter3(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:28:8: Error: Conflicts with setter 'methodAndFieldAndSetter3'.
+//   int? methodAndFieldAndSetter3;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:30:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter4'.
+//   void set methodAndFieldAndSetter4(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:31:8: Error: Conflicts with setter 'methodAndFieldAndSetter4'.
+//   int? methodAndFieldAndSetter4;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:57:12: Error: Conflicts with the implicit setter of the field 'fieldAndSetter1'.
+//   void set fieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:56:8: Error: Conflicts with setter 'fieldAndSetter1'.
+//   int? fieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:60:12: Error: Conflicts with the implicit setter of the field 'fieldAndSetter2'.
+//   void set fieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:59:8: Error: Conflicts with setter 'fieldAndSetter2'.
+//   int? fieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:64:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter1'.
+//   void set fieldAndFinalFieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:62:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter1'.
+//   int? fieldAndFinalFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:68:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter2'.
+//   void set fieldAndFinalFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:67:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter2'.
+//   int? fieldAndFinalFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:70:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter3'.
+//   void set fieldAndFinalFieldAndSetter3(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:71:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter3'.
+//   int? fieldAndFinalFieldAndSetter3;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:74:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter4'.
+//   void set fieldAndFinalFieldAndSetter4(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:76:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter4'.
+//   int? fieldAndFinalFieldAndSetter4;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:40:12: Error: 'methodAndFinalFieldAndSetter2' is already declared in this scope.
+//   void set methodAndFinalFieldAndSetter2(int? value) {}
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:39:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter2'.
+//   int? methodAndFinalFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:51:12: Error: 'methodAndSetter1' is already declared in this scope.
+//   void set methodAndSetter1(int? value) {}
+//            ^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:50:8: Context: Previous declaration of 'methodAndSetter1'.
+//   int? methodAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:12: Error: 'methodAndSetter2' is already declared in this scope.
+//   int? set methodAndSetter2() {}
+//            ^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:53:8: Context: Previous declaration of 'methodAndSetter2'.
+//   void methodAndSetter2(int? value) {}
+//        ^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:28: Error: A setter should have exactly one formal parameter.
+//   int? set methodAndSetter2() {}
+//                            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: Can't use 'methodAndField1' because it is declared more than once.
+//   c.methodAndField1 = c.methodAndField1;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:25: Error: Can't use 'methodAndField1' because it is declared more than once.
+//   c.methodAndField1 = c.methodAndField1;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:25: Error: The getter 'methodAndField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndField1'.
+//   c.methodAndField1 = c.methodAndField1;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: The setter 'methodAndField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField1'.
+//   c.methodAndField1 = c.methodAndField1;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: Can't use 'methodAndField2' because it is declared more than once.
+//   c.methodAndField2 = c.methodAndField2;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:25: Error: Can't use 'methodAndField2' because it is declared more than once.
+//   c.methodAndField2 = c.methodAndField2;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:25: Error: The getter 'methodAndField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndField2'.
+//   c.methodAndField2 = c.methodAndField2;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: The setter 'methodAndField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField2'.
+//   c.methodAndField2 = c.methodAndField2;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: Can't use 'methodAndFinalField1' because it is declared more than once.
+//   c.methodAndFinalField1;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: The getter 'methodAndFinalField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField1'.
+//   c.methodAndFinalField1;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: Can't use 'methodAndFinalField2' because it is declared more than once.
+//   c.methodAndFinalField2;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: The getter 'methodAndFinalField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField2'.
+//   c.methodAndFinalField2;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: Can't use 'methodAndFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:34: Error: Can't use 'methodAndFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:34: Error: The getter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter1'.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: The setter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter1'.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: Can't use 'methodAndFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:34: Error: Can't use 'methodAndFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:34: Error: The getter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter2'.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: The setter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter2'.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: Can't use 'methodAndFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:34: Error: Can't use 'methodAndFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:34: Error: The getter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter3'.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: The setter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter3'.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: Can't use 'methodAndFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:34: Error: Can't use 'methodAndFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:34: Error: The getter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter4'.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: The setter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter4'.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: Can't use 'methodAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: The getter 'methodAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter1'.
+//   c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: Can't use 'methodAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: The getter 'methodAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter2'.
+//   c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: Can't use 'methodAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: The getter 'methodAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter3'.
+//   c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: Can't use 'methodAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: The getter 'methodAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter4'.
+//   c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:92:26: Error: A value of type 'int? Function()' can't be assigned to a variable of type 'int?'.
+//   c.methodAndSetter1 = c.methodAndSetter1;
+//                          ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: Can't use 'fieldAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:38: Error: Can't use 'fieldAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:38: Error: The getter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter1'.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: The setter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter1'.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: Can't use 'fieldAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:38: Error: Can't use 'fieldAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:38: Error: The getter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter2'.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: The setter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter2'.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: Can't use 'fieldAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:38: Error: Can't use 'fieldAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:38: Error: The getter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter3'.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: The setter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter3'.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: Can't use 'fieldAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:38: Error: Can't use 'fieldAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:38: Error: The getter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter4'.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: The setter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter4'.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:66:14: Error: Final field 'fieldAndFinalFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? fieldAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:75:14: Error: Final field 'fieldAndFinalFieldAndSetter4' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? fieldAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Class extends core::Object {
+  field core::int? methodAndField2 = null;
+  final field core::int? methodAndFinalField2 = null;
+  field core::int? methodAndFieldAndSetter2 = null;
+  field core::int? methodAndFieldAndSetter4 = null;
+  final field core::int? methodAndFinalFieldAndSetter2 = null;
+  final field core::int? methodAndFinalFieldAndSetter4 = null;
+  field core::int? fieldAndSetter1 = null;
+  field core::int? fieldAndSetter2 = null;
+  field core::int? fieldAndFinalFieldAndSetter1 = null;
+  final field core::int? fieldAndFinalFieldAndSetter2 = null;
+  field core::int? fieldAndFinalFieldAndSetter3 = null;
+  final field core::int? fieldAndFinalFieldAndSetter4 = null;
+  synthetic constructor •() → self::Class
+    : super core::Object::•()
+    ;
+  method methodAndField1() → core::int? {}
+  method methodAndFinalField1() → core::int? {}
+  method methodAndFieldAndSetter1() → core::int? {}
+  method methodAndFieldAndSetter3() → core::int? {}
+  method methodAndFinalFieldAndSetter1() → core::int? {}
+  set methodAndFinalFieldAndSetter1(core::int? value) → void {}
+  set methodAndFinalFieldAndSetter2(core::int? value) → void {}
+  set methodAndFinalFieldAndSetter3(core::int? value) → void {}
+  method methodAndFinalFieldAndSetter3() → core::int? {}
+  set methodAndFinalFieldAndSetter4(core::int? value) → void {}
+  method methodAndSetter1() → core::int? {}
+  set methodAndSetter1(core::int? value) → void {}
+  method methodAndSetter2(core::int? value) → void {}
+  set methodAndSetter2(dynamic #synthetic) → void {
+    invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:28: Error: A setter should have exactly one formal parameter.
+  int? set methodAndSetter2() {}
+                           ^";
+    {}
+  }
+}
+static method test(self::Class c) → dynamic {
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: The setter 'methodAndField1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField1'.
+  c.methodAndField1 = c.methodAndField1;
+    ^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: The setter 'methodAndField2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField2'.
+  c.methodAndField2 = c.methodAndField2;
+    ^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: The getter 'methodAndFinalField1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField1'.
+  c.methodAndFinalField1;
+    ^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: The getter 'methodAndFinalField2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField2'.
+  c.methodAndFinalField2;
+    ^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: The setter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter1'.
+  c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: The setter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter2'.
+  c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: The setter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter3'.
+  c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: The setter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter4'.
+  c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndFinalFieldAndSetter1} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: The getter 'methodAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter1'.
+  c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndFinalFieldAndSetter2} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: The getter 'methodAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter2'.
+  c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndFinalFieldAndSetter3} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: The getter 'methodAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter3'.
+  c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndFinalFieldAndSetter4} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: The getter 'methodAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter4'.
+  c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndSetter1} = let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:92:26: Error: A value of type 'int? Function()' can't be assigned to a variable of type 'int?'.
+  c.methodAndSetter1 = c.methodAndSetter1;
+                         ^" in c.{self::Class::methodAndSetter1} as{TypeError,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndSetter2} = c.{self::Class::methodAndSetter2};
+  c.{self::Class::fieldAndSetter1} = c.{self::Class::fieldAndSetter1};
+  c.{self::Class::fieldAndSetter2} = c.{self::Class::fieldAndSetter2};
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: The setter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter1'.
+  c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: The setter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter2'.
+  c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: The setter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter3'.
+  c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: The setter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter4'.
+  c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/instance_duplicates.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.strong.transformed.expect
new file mode 100644
index 0000000..98e8bb0
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.strong.transformed.expect
@@ -0,0 +1,628 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:7:8: Error: 'methodAndField1' is already declared in this scope.
+//   int? methodAndField1;
+//        ^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:6:8: Context: Previous declaration of 'methodAndField1'.
+//   int? methodAndField1() {}
+//        ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:10:8: Error: 'methodAndField2' is already declared in this scope.
+//   int? methodAndField2() {}
+//        ^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:9:8: Context: Previous declaration of 'methodAndField2'.
+//   int? methodAndField2;
+//        ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:13:14: Error: 'methodAndFinalField1' is already declared in this scope.
+//   final int? methodAndFinalField1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:12:8: Context: Previous declaration of 'methodAndFinalField1'.
+//   int? methodAndFinalField1() {}
+//        ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:16:8: Error: 'methodAndFinalField2' is already declared in this scope.
+//   int? methodAndFinalField2() {}
+//        ^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:15:14: Context: Previous declaration of 'methodAndFinalField2'.
+//   final int? methodAndFinalField2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:19:8: Error: 'methodAndFieldAndSetter1' is already declared in this scope.
+//   int? methodAndFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:18:8: Context: Previous declaration of 'methodAndFieldAndSetter1'.
+//   int? methodAndFieldAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:23:8: Error: 'methodAndFieldAndSetter2' is already declared in this scope.
+//   int? methodAndFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:22:8: Context: Previous declaration of 'methodAndFieldAndSetter2'.
+//   int? methodAndFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:28:8: Error: 'methodAndFieldAndSetter3' is already declared in this scope.
+//   int? methodAndFieldAndSetter3;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:27:8: Context: Previous declaration of 'methodAndFieldAndSetter3'.
+//   int? methodAndFieldAndSetter3() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:32:8: Error: 'methodAndFieldAndSetter4' is already declared in this scope.
+//   int? methodAndFieldAndSetter4() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:31:8: Context: Previous declaration of 'methodAndFieldAndSetter4'.
+//   int? methodAndFieldAndSetter4;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:35:14: Error: 'methodAndFinalFieldAndSetter1' is already declared in this scope.
+//   final int? methodAndFinalFieldAndSetter1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:34:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter1'.
+//   int? methodAndFinalFieldAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:39:8: Error: 'methodAndFinalFieldAndSetter2' is already declared in this scope.
+//   int? methodAndFinalFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:38:14: Context: Previous declaration of 'methodAndFinalFieldAndSetter2'.
+//   final int? methodAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:44:14: Error: 'methodAndFinalFieldAndSetter3' is already declared in this scope.
+//   final int? methodAndFinalFieldAndSetter3 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:43:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter3'.
+//   int? methodAndFinalFieldAndSetter3() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:48:8: Error: 'methodAndFinalFieldAndSetter4' is already declared in this scope.
+//   int? methodAndFinalFieldAndSetter4() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:47:14: Context: Previous declaration of 'methodAndFinalFieldAndSetter4'.
+//   final int? methodAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:3: Error: The return type of the setter must be 'void' or absent.
+// Try removing the return type, or define a method rather than a setter.
+//   int? set methodAndSetter2() {}
+//   ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:63:14: Error: 'fieldAndFinalFieldAndSetter1' is already declared in this scope.
+//   final int? fieldAndFinalFieldAndSetter1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:62:8: Context: Previous declaration of 'fieldAndFinalFieldAndSetter1'.
+//   int? fieldAndFinalFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:67:8: Error: 'fieldAndFinalFieldAndSetter2' is already declared in this scope.
+//   int? fieldAndFinalFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:66:14: Context: Previous declaration of 'fieldAndFinalFieldAndSetter2'.
+//   final int? fieldAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:72:14: Error: 'fieldAndFinalFieldAndSetter3' is already declared in this scope.
+//   final int? fieldAndFinalFieldAndSetter3 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:71:8: Context: Previous declaration of 'fieldAndFinalFieldAndSetter3'.
+//   int? fieldAndFinalFieldAndSetter3;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:76:8: Error: 'fieldAndFinalFieldAndSetter4' is already declared in this scope.
+//   int? fieldAndFinalFieldAndSetter4;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:75:14: Context: Previous declaration of 'fieldAndFinalFieldAndSetter4'.
+//   final int? fieldAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:20:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter1'.
+//   void set methodAndFieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:19:8: Error: Conflicts with setter 'methodAndFieldAndSetter1'.
+//   int? methodAndFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:24:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter2'.
+//   void set methodAndFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:22:8: Error: Conflicts with setter 'methodAndFieldAndSetter2'.
+//   int? methodAndFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:26:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter3'.
+//   void set methodAndFieldAndSetter3(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:28:8: Error: Conflicts with setter 'methodAndFieldAndSetter3'.
+//   int? methodAndFieldAndSetter3;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:30:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter4'.
+//   void set methodAndFieldAndSetter4(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:31:8: Error: Conflicts with setter 'methodAndFieldAndSetter4'.
+//   int? methodAndFieldAndSetter4;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:57:12: Error: Conflicts with the implicit setter of the field 'fieldAndSetter1'.
+//   void set fieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:56:8: Error: Conflicts with setter 'fieldAndSetter1'.
+//   int? fieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:60:12: Error: Conflicts with the implicit setter of the field 'fieldAndSetter2'.
+//   void set fieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:59:8: Error: Conflicts with setter 'fieldAndSetter2'.
+//   int? fieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:64:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter1'.
+//   void set fieldAndFinalFieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:62:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter1'.
+//   int? fieldAndFinalFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:68:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter2'.
+//   void set fieldAndFinalFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:67:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter2'.
+//   int? fieldAndFinalFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:70:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter3'.
+//   void set fieldAndFinalFieldAndSetter3(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:71:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter3'.
+//   int? fieldAndFinalFieldAndSetter3;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:74:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter4'.
+//   void set fieldAndFinalFieldAndSetter4(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:76:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter4'.
+//   int? fieldAndFinalFieldAndSetter4;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:40:12: Error: 'methodAndFinalFieldAndSetter2' is already declared in this scope.
+//   void set methodAndFinalFieldAndSetter2(int? value) {}
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:39:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter2'.
+//   int? methodAndFinalFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:51:12: Error: 'methodAndSetter1' is already declared in this scope.
+//   void set methodAndSetter1(int? value) {}
+//            ^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:50:8: Context: Previous declaration of 'methodAndSetter1'.
+//   int? methodAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:12: Error: 'methodAndSetter2' is already declared in this scope.
+//   int? set methodAndSetter2() {}
+//            ^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:53:8: Context: Previous declaration of 'methodAndSetter2'.
+//   void methodAndSetter2(int? value) {}
+//        ^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:28: Error: A setter should have exactly one formal parameter.
+//   int? set methodAndSetter2() {}
+//                            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: Can't use 'methodAndField1' because it is declared more than once.
+//   c.methodAndField1 = c.methodAndField1;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:25: Error: Can't use 'methodAndField1' because it is declared more than once.
+//   c.methodAndField1 = c.methodAndField1;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:25: Error: The getter 'methodAndField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndField1'.
+//   c.methodAndField1 = c.methodAndField1;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: The setter 'methodAndField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField1'.
+//   c.methodAndField1 = c.methodAndField1;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: Can't use 'methodAndField2' because it is declared more than once.
+//   c.methodAndField2 = c.methodAndField2;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:25: Error: Can't use 'methodAndField2' because it is declared more than once.
+//   c.methodAndField2 = c.methodAndField2;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:25: Error: The getter 'methodAndField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndField2'.
+//   c.methodAndField2 = c.methodAndField2;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: The setter 'methodAndField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField2'.
+//   c.methodAndField2 = c.methodAndField2;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: Can't use 'methodAndFinalField1' because it is declared more than once.
+//   c.methodAndFinalField1;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: The getter 'methodAndFinalField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField1'.
+//   c.methodAndFinalField1;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: Can't use 'methodAndFinalField2' because it is declared more than once.
+//   c.methodAndFinalField2;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: The getter 'methodAndFinalField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField2'.
+//   c.methodAndFinalField2;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: Can't use 'methodAndFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:34: Error: Can't use 'methodAndFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:34: Error: The getter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter1'.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: The setter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter1'.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: Can't use 'methodAndFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:34: Error: Can't use 'methodAndFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:34: Error: The getter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter2'.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: The setter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter2'.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: Can't use 'methodAndFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:34: Error: Can't use 'methodAndFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:34: Error: The getter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter3'.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: The setter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter3'.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: Can't use 'methodAndFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:34: Error: Can't use 'methodAndFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:34: Error: The getter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter4'.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: The setter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter4'.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: Can't use 'methodAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: The getter 'methodAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter1'.
+//   c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: Can't use 'methodAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: The getter 'methodAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter2'.
+//   c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: Can't use 'methodAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: The getter 'methodAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter3'.
+//   c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: Can't use 'methodAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: The getter 'methodAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter4'.
+//   c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:92:26: Error: A value of type 'int? Function()' can't be assigned to a variable of type 'int?'.
+//   c.methodAndSetter1 = c.methodAndSetter1;
+//                          ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: Can't use 'fieldAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:38: Error: Can't use 'fieldAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:38: Error: The getter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter1'.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: The setter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter1'.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: Can't use 'fieldAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:38: Error: Can't use 'fieldAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:38: Error: The getter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter2'.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: The setter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter2'.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: Can't use 'fieldAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:38: Error: Can't use 'fieldAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:38: Error: The getter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter3'.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: The setter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter3'.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: Can't use 'fieldAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:38: Error: Can't use 'fieldAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:38: Error: The getter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter4'.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: The setter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter4'.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:66:14: Error: Final field 'fieldAndFinalFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? fieldAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:75:14: Error: Final field 'fieldAndFinalFieldAndSetter4' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? fieldAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Class extends core::Object {
+  field core::int? methodAndField2 = null;
+  final field core::int? methodAndFinalField2 = null;
+  field core::int? methodAndFieldAndSetter2 = null;
+  field core::int? methodAndFieldAndSetter4 = null;
+  final field core::int? methodAndFinalFieldAndSetter2 = null;
+  final field core::int? methodAndFinalFieldAndSetter4 = null;
+  field core::int? fieldAndSetter1 = null;
+  field core::int? fieldAndSetter2 = null;
+  field core::int? fieldAndFinalFieldAndSetter1 = null;
+  final field core::int? fieldAndFinalFieldAndSetter2 = null;
+  field core::int? fieldAndFinalFieldAndSetter3 = null;
+  final field core::int? fieldAndFinalFieldAndSetter4 = null;
+  synthetic constructor •() → self::Class
+    : super core::Object::•()
+    ;
+  method methodAndField1() → core::int? {}
+  method methodAndFinalField1() → core::int? {}
+  method methodAndFieldAndSetter1() → core::int? {}
+  method methodAndFieldAndSetter3() → core::int? {}
+  method methodAndFinalFieldAndSetter1() → core::int? {}
+  set methodAndFinalFieldAndSetter1(core::int? value) → void {}
+  set methodAndFinalFieldAndSetter2(core::int? value) → void {}
+  set methodAndFinalFieldAndSetter3(core::int? value) → void {}
+  method methodAndFinalFieldAndSetter3() → core::int? {}
+  set methodAndFinalFieldAndSetter4(core::int? value) → void {}
+  method methodAndSetter1() → core::int? {}
+  set methodAndSetter1(core::int? value) → void {}
+  method methodAndSetter2(core::int? value) → void {}
+  set methodAndSetter2(dynamic #synthetic) → void {
+    invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:28: Error: A setter should have exactly one formal parameter.
+  int? set methodAndSetter2() {}
+                           ^";
+    {}
+  }
+}
+static method test(self::Class c) → dynamic {
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: The setter 'methodAndField1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField1'.
+  c.methodAndField1 = c.methodAndField1;
+    ^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: The setter 'methodAndField2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField2'.
+  c.methodAndField2 = c.methodAndField2;
+    ^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: The getter 'methodAndFinalField1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField1'.
+  c.methodAndFinalField1;
+    ^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: The getter 'methodAndFinalField2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField2'.
+  c.methodAndFinalField2;
+    ^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: The setter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter1'.
+  c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: The setter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter2'.
+  c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: The setter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter3'.
+  c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: The setter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter4'.
+  c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndFinalFieldAndSetter1} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: The getter 'methodAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter1'.
+  c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndFinalFieldAndSetter2} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: The getter 'methodAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter2'.
+  c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndFinalFieldAndSetter3} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: The getter 'methodAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter3'.
+  c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndFinalFieldAndSetter4} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: The getter 'methodAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter4'.
+  c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndSetter1} = let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:92:26: Error: A value of type 'int? Function()' can't be assigned to a variable of type 'int?'.
+  c.methodAndSetter1 = c.methodAndSetter1;
+                         ^" in c.{self::Class::methodAndSetter1} as{TypeError,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndSetter2} = c.{self::Class::methodAndSetter2};
+  c.{self::Class::fieldAndSetter1} = c.{self::Class::fieldAndSetter1};
+  c.{self::Class::fieldAndSetter2} = c.{self::Class::fieldAndSetter2};
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: The setter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter1'.
+  c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: The setter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter2'.
+  c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: The setter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter3'.
+  c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: The setter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter4'.
+  c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/instance_duplicates.dart.textual_outline.expect b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.textual_outline.expect
new file mode 100644
index 0000000..6c71271
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.textual_outline.expect
@@ -0,0 +1,57 @@
+class Class {
+  int? methodAndField1() {}
+  int? methodAndField1;
+  int? methodAndField2;
+  int? methodAndField2() {}
+  int? methodAndFinalField1() {}
+  final int? methodAndFinalField1 = 0;
+  final int? methodAndFinalField2 = 0;
+  int? methodAndFinalField2() {}
+  int? methodAndFieldAndSetter1() {}
+  int? methodAndFieldAndSetter1;
+  void set methodAndFieldAndSetter1(int? value) {}
+  int? methodAndFieldAndSetter2;
+  int? methodAndFieldAndSetter2() {}
+  void set methodAndFieldAndSetter2(int? value) {}
+  void set methodAndFieldAndSetter3(int? value) {}
+  int? methodAndFieldAndSetter3() {}
+  int? methodAndFieldAndSetter3;
+  void set methodAndFieldAndSetter4(int? value) {}
+  int? methodAndFieldAndSetter4;
+  int? methodAndFieldAndSetter4() {}
+  int? methodAndFinalFieldAndSetter1() {}
+  final int? methodAndFinalFieldAndSetter1 = 0;
+  void set methodAndFinalFieldAndSetter1(int? value) {}
+  final int? methodAndFinalFieldAndSetter2 = 0;
+  int? methodAndFinalFieldAndSetter2() {}
+  void set methodAndFinalFieldAndSetter2(int? value) {}
+  void set methodAndFinalFieldAndSetter3(int? value) {}
+  int? methodAndFinalFieldAndSetter3() {}
+  final int? methodAndFinalFieldAndSetter3 = 0;
+  void set methodAndFinalFieldAndSetter4(int? value) {}
+  final int? methodAndFinalFieldAndSetter4 = 0;
+  int? methodAndFinalFieldAndSetter4() {}
+  int? methodAndSetter1() {}
+  void set methodAndSetter1(int? value) {}
+  void methodAndSetter2(int? value) {}
+  int? set methodAndSetter2() {}
+  int? fieldAndSetter1;
+  void set fieldAndSetter1(int? value) {}
+  int? fieldAndSetter2;
+  void set fieldAndSetter2(int? value) {}
+  int? fieldAndFinalFieldAndSetter1;
+  final int? fieldAndFinalFieldAndSetter1 = 0;
+  void set fieldAndFinalFieldAndSetter1(int? value) {}
+  final int? fieldAndFinalFieldAndSetter2 = 0;
+  int? fieldAndFinalFieldAndSetter2;
+  void set fieldAndFinalFieldAndSetter2(int? value) {}
+  void set fieldAndFinalFieldAndSetter3(int? value) {}
+  int? fieldAndFinalFieldAndSetter3;
+  final int? fieldAndFinalFieldAndSetter3 = 0;
+  void set fieldAndFinalFieldAndSetter4(int? value) {}
+  final int? fieldAndFinalFieldAndSetter4 = 0;
+  int? fieldAndFinalFieldAndSetter4;
+}
+
+test(Class c) {}
+main() {}
diff --git a/pkg/front_end/testcases/nnbd/instance_duplicates.dart.textual_outline_modelled.expect b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.textual_outline_modelled.expect
new file mode 100644
index 0000000..f328f42
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.textual_outline_modelled.expect
@@ -0,0 +1,57 @@
+class Class {
+  final int? fieldAndFinalFieldAndSetter1 = 0;
+  final int? fieldAndFinalFieldAndSetter2 = 0;
+  final int? fieldAndFinalFieldAndSetter3 = 0;
+  final int? fieldAndFinalFieldAndSetter4 = 0;
+  final int? methodAndFinalField1 = 0;
+  final int? methodAndFinalField2 = 0;
+  final int? methodAndFinalFieldAndSetter1 = 0;
+  final int? methodAndFinalFieldAndSetter2 = 0;
+  final int? methodAndFinalFieldAndSetter3 = 0;
+  final int? methodAndFinalFieldAndSetter4 = 0;
+  int? fieldAndFinalFieldAndSetter1;
+  int? fieldAndFinalFieldAndSetter2;
+  int? fieldAndFinalFieldAndSetter3;
+  int? fieldAndFinalFieldAndSetter4;
+  int? fieldAndSetter1;
+  int? fieldAndSetter2;
+  int? methodAndField1() {}
+  int? methodAndField1;
+  int? methodAndField2() {}
+  int? methodAndField2;
+  int? methodAndFieldAndSetter1() {}
+  int? methodAndFieldAndSetter1;
+  int? methodAndFieldAndSetter2() {}
+  int? methodAndFieldAndSetter2;
+  int? methodAndFieldAndSetter3() {}
+  int? methodAndFieldAndSetter3;
+  int? methodAndFieldAndSetter4() {}
+  int? methodAndFieldAndSetter4;
+  int? methodAndFinalField1() {}
+  int? methodAndFinalField2() {}
+  int? methodAndFinalFieldAndSetter1() {}
+  int? methodAndFinalFieldAndSetter2() {}
+  int? methodAndFinalFieldAndSetter3() {}
+  int? methodAndFinalFieldAndSetter4() {}
+  int? methodAndSetter1() {}
+  int? set methodAndSetter2() {}
+  void methodAndSetter2(int? value) {}
+  void set fieldAndFinalFieldAndSetter1(int? value) {}
+  void set fieldAndFinalFieldAndSetter2(int? value) {}
+  void set fieldAndFinalFieldAndSetter3(int? value) {}
+  void set fieldAndFinalFieldAndSetter4(int? value) {}
+  void set fieldAndSetter1(int? value) {}
+  void set fieldAndSetter2(int? value) {}
+  void set methodAndFieldAndSetter1(int? value) {}
+  void set methodAndFieldAndSetter2(int? value) {}
+  void set methodAndFieldAndSetter3(int? value) {}
+  void set methodAndFieldAndSetter4(int? value) {}
+  void set methodAndFinalFieldAndSetter1(int? value) {}
+  void set methodAndFinalFieldAndSetter2(int? value) {}
+  void set methodAndFinalFieldAndSetter3(int? value) {}
+  void set methodAndFinalFieldAndSetter4(int? value) {}
+  void set methodAndSetter1(int? value) {}
+}
+
+main() {}
+test(Class c) {}
diff --git a/pkg/front_end/testcases/nnbd/instance_duplicates.dart.weak.expect b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.weak.expect
new file mode 100644
index 0000000..8687a05
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.weak.expect
@@ -0,0 +1,628 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:7:8: Error: 'methodAndField1' is already declared in this scope.
+//   int? methodAndField1;
+//        ^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:6:8: Context: Previous declaration of 'methodAndField1'.
+//   int? methodAndField1() {}
+//        ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:10:8: Error: 'methodAndField2' is already declared in this scope.
+//   int? methodAndField2() {}
+//        ^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:9:8: Context: Previous declaration of 'methodAndField2'.
+//   int? methodAndField2;
+//        ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:13:14: Error: 'methodAndFinalField1' is already declared in this scope.
+//   final int? methodAndFinalField1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:12:8: Context: Previous declaration of 'methodAndFinalField1'.
+//   int? methodAndFinalField1() {}
+//        ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:16:8: Error: 'methodAndFinalField2' is already declared in this scope.
+//   int? methodAndFinalField2() {}
+//        ^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:15:14: Context: Previous declaration of 'methodAndFinalField2'.
+//   final int? methodAndFinalField2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:19:8: Error: 'methodAndFieldAndSetter1' is already declared in this scope.
+//   int? methodAndFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:18:8: Context: Previous declaration of 'methodAndFieldAndSetter1'.
+//   int? methodAndFieldAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:23:8: Error: 'methodAndFieldAndSetter2' is already declared in this scope.
+//   int? methodAndFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:22:8: Context: Previous declaration of 'methodAndFieldAndSetter2'.
+//   int? methodAndFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:28:8: Error: 'methodAndFieldAndSetter3' is already declared in this scope.
+//   int? methodAndFieldAndSetter3;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:27:8: Context: Previous declaration of 'methodAndFieldAndSetter3'.
+//   int? methodAndFieldAndSetter3() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:32:8: Error: 'methodAndFieldAndSetter4' is already declared in this scope.
+//   int? methodAndFieldAndSetter4() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:31:8: Context: Previous declaration of 'methodAndFieldAndSetter4'.
+//   int? methodAndFieldAndSetter4;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:35:14: Error: 'methodAndFinalFieldAndSetter1' is already declared in this scope.
+//   final int? methodAndFinalFieldAndSetter1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:34:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter1'.
+//   int? methodAndFinalFieldAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:39:8: Error: 'methodAndFinalFieldAndSetter2' is already declared in this scope.
+//   int? methodAndFinalFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:38:14: Context: Previous declaration of 'methodAndFinalFieldAndSetter2'.
+//   final int? methodAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:44:14: Error: 'methodAndFinalFieldAndSetter3' is already declared in this scope.
+//   final int? methodAndFinalFieldAndSetter3 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:43:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter3'.
+//   int? methodAndFinalFieldAndSetter3() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:48:8: Error: 'methodAndFinalFieldAndSetter4' is already declared in this scope.
+//   int? methodAndFinalFieldAndSetter4() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:47:14: Context: Previous declaration of 'methodAndFinalFieldAndSetter4'.
+//   final int? methodAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:3: Error: The return type of the setter must be 'void' or absent.
+// Try removing the return type, or define a method rather than a setter.
+//   int? set methodAndSetter2() {}
+//   ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:63:14: Error: 'fieldAndFinalFieldAndSetter1' is already declared in this scope.
+//   final int? fieldAndFinalFieldAndSetter1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:62:8: Context: Previous declaration of 'fieldAndFinalFieldAndSetter1'.
+//   int? fieldAndFinalFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:67:8: Error: 'fieldAndFinalFieldAndSetter2' is already declared in this scope.
+//   int? fieldAndFinalFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:66:14: Context: Previous declaration of 'fieldAndFinalFieldAndSetter2'.
+//   final int? fieldAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:72:14: Error: 'fieldAndFinalFieldAndSetter3' is already declared in this scope.
+//   final int? fieldAndFinalFieldAndSetter3 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:71:8: Context: Previous declaration of 'fieldAndFinalFieldAndSetter3'.
+//   int? fieldAndFinalFieldAndSetter3;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:76:8: Error: 'fieldAndFinalFieldAndSetter4' is already declared in this scope.
+//   int? fieldAndFinalFieldAndSetter4;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:75:14: Context: Previous declaration of 'fieldAndFinalFieldAndSetter4'.
+//   final int? fieldAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:20:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter1'.
+//   void set methodAndFieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:19:8: Error: Conflicts with setter 'methodAndFieldAndSetter1'.
+//   int? methodAndFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:24:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter2'.
+//   void set methodAndFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:22:8: Error: Conflicts with setter 'methodAndFieldAndSetter2'.
+//   int? methodAndFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:26:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter3'.
+//   void set methodAndFieldAndSetter3(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:28:8: Error: Conflicts with setter 'methodAndFieldAndSetter3'.
+//   int? methodAndFieldAndSetter3;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:30:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter4'.
+//   void set methodAndFieldAndSetter4(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:31:8: Error: Conflicts with setter 'methodAndFieldAndSetter4'.
+//   int? methodAndFieldAndSetter4;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:57:12: Error: Conflicts with the implicit setter of the field 'fieldAndSetter1'.
+//   void set fieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:56:8: Error: Conflicts with setter 'fieldAndSetter1'.
+//   int? fieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:60:12: Error: Conflicts with the implicit setter of the field 'fieldAndSetter2'.
+//   void set fieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:59:8: Error: Conflicts with setter 'fieldAndSetter2'.
+//   int? fieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:64:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter1'.
+//   void set fieldAndFinalFieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:62:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter1'.
+//   int? fieldAndFinalFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:68:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter2'.
+//   void set fieldAndFinalFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:67:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter2'.
+//   int? fieldAndFinalFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:70:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter3'.
+//   void set fieldAndFinalFieldAndSetter3(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:71:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter3'.
+//   int? fieldAndFinalFieldAndSetter3;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:74:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter4'.
+//   void set fieldAndFinalFieldAndSetter4(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:76:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter4'.
+//   int? fieldAndFinalFieldAndSetter4;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:40:12: Error: 'methodAndFinalFieldAndSetter2' is already declared in this scope.
+//   void set methodAndFinalFieldAndSetter2(int? value) {}
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:39:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter2'.
+//   int? methodAndFinalFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:51:12: Error: 'methodAndSetter1' is already declared in this scope.
+//   void set methodAndSetter1(int? value) {}
+//            ^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:50:8: Context: Previous declaration of 'methodAndSetter1'.
+//   int? methodAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:12: Error: 'methodAndSetter2' is already declared in this scope.
+//   int? set methodAndSetter2() {}
+//            ^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:53:8: Context: Previous declaration of 'methodAndSetter2'.
+//   void methodAndSetter2(int? value) {}
+//        ^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:28: Error: A setter should have exactly one formal parameter.
+//   int? set methodAndSetter2() {}
+//                            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: Can't use 'methodAndField1' because it is declared more than once.
+//   c.methodAndField1 = c.methodAndField1;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:25: Error: Can't use 'methodAndField1' because it is declared more than once.
+//   c.methodAndField1 = c.methodAndField1;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:25: Error: The getter 'methodAndField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndField1'.
+//   c.methodAndField1 = c.methodAndField1;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: The setter 'methodAndField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField1'.
+//   c.methodAndField1 = c.methodAndField1;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: Can't use 'methodAndField2' because it is declared more than once.
+//   c.methodAndField2 = c.methodAndField2;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:25: Error: Can't use 'methodAndField2' because it is declared more than once.
+//   c.methodAndField2 = c.methodAndField2;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:25: Error: The getter 'methodAndField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndField2'.
+//   c.methodAndField2 = c.methodAndField2;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: The setter 'methodAndField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField2'.
+//   c.methodAndField2 = c.methodAndField2;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: Can't use 'methodAndFinalField1' because it is declared more than once.
+//   c.methodAndFinalField1;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: The getter 'methodAndFinalField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField1'.
+//   c.methodAndFinalField1;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: Can't use 'methodAndFinalField2' because it is declared more than once.
+//   c.methodAndFinalField2;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: The getter 'methodAndFinalField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField2'.
+//   c.methodAndFinalField2;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: Can't use 'methodAndFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:34: Error: Can't use 'methodAndFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:34: Error: The getter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter1'.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: The setter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter1'.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: Can't use 'methodAndFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:34: Error: Can't use 'methodAndFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:34: Error: The getter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter2'.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: The setter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter2'.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: Can't use 'methodAndFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:34: Error: Can't use 'methodAndFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:34: Error: The getter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter3'.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: The setter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter3'.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: Can't use 'methodAndFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:34: Error: Can't use 'methodAndFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:34: Error: The getter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter4'.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: The setter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter4'.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: Can't use 'methodAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: The getter 'methodAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter1'.
+//   c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: Can't use 'methodAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: The getter 'methodAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter2'.
+//   c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: Can't use 'methodAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: The getter 'methodAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter3'.
+//   c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: Can't use 'methodAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: The getter 'methodAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter4'.
+//   c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:92:26: Error: A value of type 'int? Function()' can't be assigned to a variable of type 'int?'.
+//   c.methodAndSetter1 = c.methodAndSetter1;
+//                          ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: Can't use 'fieldAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:38: Error: Can't use 'fieldAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:38: Error: The getter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter1'.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: The setter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter1'.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: Can't use 'fieldAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:38: Error: Can't use 'fieldAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:38: Error: The getter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter2'.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: The setter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter2'.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: Can't use 'fieldAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:38: Error: Can't use 'fieldAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:38: Error: The getter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter3'.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: The setter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter3'.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: Can't use 'fieldAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:38: Error: Can't use 'fieldAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:38: Error: The getter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter4'.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: The setter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter4'.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:66:14: Error: Final field 'fieldAndFinalFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? fieldAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:75:14: Error: Final field 'fieldAndFinalFieldAndSetter4' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? fieldAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Class extends core::Object {
+  field core::int? methodAndField2 = null;
+  final field core::int? methodAndFinalField2 = null;
+  field core::int? methodAndFieldAndSetter2 = null;
+  field core::int? methodAndFieldAndSetter4 = null;
+  final field core::int? methodAndFinalFieldAndSetter2 = null;
+  final field core::int? methodAndFinalFieldAndSetter4 = null;
+  field core::int? fieldAndSetter1 = null;
+  field core::int? fieldAndSetter2 = null;
+  field core::int? fieldAndFinalFieldAndSetter1 = null;
+  final field core::int? fieldAndFinalFieldAndSetter2 = null;
+  field core::int? fieldAndFinalFieldAndSetter3 = null;
+  final field core::int? fieldAndFinalFieldAndSetter4 = null;
+  synthetic constructor •() → self::Class
+    : super core::Object::•()
+    ;
+  method methodAndField1() → core::int? {}
+  method methodAndFinalField1() → core::int? {}
+  method methodAndFieldAndSetter1() → core::int? {}
+  method methodAndFieldAndSetter3() → core::int? {}
+  method methodAndFinalFieldAndSetter1() → core::int? {}
+  set methodAndFinalFieldAndSetter1(core::int? value) → void {}
+  set methodAndFinalFieldAndSetter2(core::int? value) → void {}
+  set methodAndFinalFieldAndSetter3(core::int? value) → void {}
+  method methodAndFinalFieldAndSetter3() → core::int? {}
+  set methodAndFinalFieldAndSetter4(core::int? value) → void {}
+  method methodAndSetter1() → core::int? {}
+  set methodAndSetter1(core::int? value) → void {}
+  method methodAndSetter2(core::int? value) → void {}
+  set methodAndSetter2(dynamic #synthetic) → void {
+    invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:28: Error: A setter should have exactly one formal parameter.
+  int? set methodAndSetter2() {}
+                           ^";
+    {}
+  }
+}
+static method test(self::Class c) → dynamic {
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: The setter 'methodAndField1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField1'.
+  c.methodAndField1 = c.methodAndField1;
+    ^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: The setter 'methodAndField2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField2'.
+  c.methodAndField2 = c.methodAndField2;
+    ^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: The getter 'methodAndFinalField1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField1'.
+  c.methodAndFinalField1;
+    ^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: The getter 'methodAndFinalField2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField2'.
+  c.methodAndFinalField2;
+    ^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: The setter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter1'.
+  c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: The setter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter2'.
+  c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: The setter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter3'.
+  c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: The setter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter4'.
+  c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndFinalFieldAndSetter1} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: The getter 'methodAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter1'.
+  c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndFinalFieldAndSetter2} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: The getter 'methodAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter2'.
+  c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndFinalFieldAndSetter3} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: The getter 'methodAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter3'.
+  c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndFinalFieldAndSetter4} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: The getter 'methodAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter4'.
+  c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^" as{TypeError,ForDynamic,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndSetter1} = let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:92:26: Error: A value of type 'int? Function()' can't be assigned to a variable of type 'int?'.
+  c.methodAndSetter1 = c.methodAndSetter1;
+                         ^" in c.{self::Class::methodAndSetter1} as{TypeError,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndSetter2} = c.{self::Class::methodAndSetter2};
+  c.{self::Class::fieldAndSetter1} = c.{self::Class::fieldAndSetter1};
+  c.{self::Class::fieldAndSetter2} = c.{self::Class::fieldAndSetter2};
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: The setter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter1'.
+  c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: The setter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter2'.
+  c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: The setter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter3'.
+  c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: The setter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter4'.
+  c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/instance_duplicates.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.weak.transformed.expect
new file mode 100644
index 0000000..98e8bb0
--- /dev/null
+++ b/pkg/front_end/testcases/nnbd/instance_duplicates.dart.weak.transformed.expect
@@ -0,0 +1,628 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:7:8: Error: 'methodAndField1' is already declared in this scope.
+//   int? methodAndField1;
+//        ^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:6:8: Context: Previous declaration of 'methodAndField1'.
+//   int? methodAndField1() {}
+//        ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:10:8: Error: 'methodAndField2' is already declared in this scope.
+//   int? methodAndField2() {}
+//        ^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:9:8: Context: Previous declaration of 'methodAndField2'.
+//   int? methodAndField2;
+//        ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:13:14: Error: 'methodAndFinalField1' is already declared in this scope.
+//   final int? methodAndFinalField1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:12:8: Context: Previous declaration of 'methodAndFinalField1'.
+//   int? methodAndFinalField1() {}
+//        ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:16:8: Error: 'methodAndFinalField2' is already declared in this scope.
+//   int? methodAndFinalField2() {}
+//        ^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:15:14: Context: Previous declaration of 'methodAndFinalField2'.
+//   final int? methodAndFinalField2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:19:8: Error: 'methodAndFieldAndSetter1' is already declared in this scope.
+//   int? methodAndFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:18:8: Context: Previous declaration of 'methodAndFieldAndSetter1'.
+//   int? methodAndFieldAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:23:8: Error: 'methodAndFieldAndSetter2' is already declared in this scope.
+//   int? methodAndFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:22:8: Context: Previous declaration of 'methodAndFieldAndSetter2'.
+//   int? methodAndFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:28:8: Error: 'methodAndFieldAndSetter3' is already declared in this scope.
+//   int? methodAndFieldAndSetter3;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:27:8: Context: Previous declaration of 'methodAndFieldAndSetter3'.
+//   int? methodAndFieldAndSetter3() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:32:8: Error: 'methodAndFieldAndSetter4' is already declared in this scope.
+//   int? methodAndFieldAndSetter4() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:31:8: Context: Previous declaration of 'methodAndFieldAndSetter4'.
+//   int? methodAndFieldAndSetter4;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:35:14: Error: 'methodAndFinalFieldAndSetter1' is already declared in this scope.
+//   final int? methodAndFinalFieldAndSetter1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:34:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter1'.
+//   int? methodAndFinalFieldAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:39:8: Error: 'methodAndFinalFieldAndSetter2' is already declared in this scope.
+//   int? methodAndFinalFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:38:14: Context: Previous declaration of 'methodAndFinalFieldAndSetter2'.
+//   final int? methodAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:44:14: Error: 'methodAndFinalFieldAndSetter3' is already declared in this scope.
+//   final int? methodAndFinalFieldAndSetter3 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:43:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter3'.
+//   int? methodAndFinalFieldAndSetter3() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:48:8: Error: 'methodAndFinalFieldAndSetter4' is already declared in this scope.
+//   int? methodAndFinalFieldAndSetter4() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:47:14: Context: Previous declaration of 'methodAndFinalFieldAndSetter4'.
+//   final int? methodAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:3: Error: The return type of the setter must be 'void' or absent.
+// Try removing the return type, or define a method rather than a setter.
+//   int? set methodAndSetter2() {}
+//   ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:63:14: Error: 'fieldAndFinalFieldAndSetter1' is already declared in this scope.
+//   final int? fieldAndFinalFieldAndSetter1 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:62:8: Context: Previous declaration of 'fieldAndFinalFieldAndSetter1'.
+//   int? fieldAndFinalFieldAndSetter1;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:67:8: Error: 'fieldAndFinalFieldAndSetter2' is already declared in this scope.
+//   int? fieldAndFinalFieldAndSetter2;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:66:14: Context: Previous declaration of 'fieldAndFinalFieldAndSetter2'.
+//   final int? fieldAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:72:14: Error: 'fieldAndFinalFieldAndSetter3' is already declared in this scope.
+//   final int? fieldAndFinalFieldAndSetter3 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:71:8: Context: Previous declaration of 'fieldAndFinalFieldAndSetter3'.
+//   int? fieldAndFinalFieldAndSetter3;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:76:8: Error: 'fieldAndFinalFieldAndSetter4' is already declared in this scope.
+//   int? fieldAndFinalFieldAndSetter4;
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:75:14: Context: Previous declaration of 'fieldAndFinalFieldAndSetter4'.
+//   final int? fieldAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:20:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter1'.
+//   void set methodAndFieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:19:8: Error: Conflicts with setter 'methodAndFieldAndSetter1'.
+//   int? methodAndFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:24:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter2'.
+//   void set methodAndFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:22:8: Error: Conflicts with setter 'methodAndFieldAndSetter2'.
+//   int? methodAndFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:26:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter3'.
+//   void set methodAndFieldAndSetter3(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:28:8: Error: Conflicts with setter 'methodAndFieldAndSetter3'.
+//   int? methodAndFieldAndSetter3;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:30:12: Error: Conflicts with the implicit setter of the field 'methodAndFieldAndSetter4'.
+//   void set methodAndFieldAndSetter4(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:31:8: Error: Conflicts with setter 'methodAndFieldAndSetter4'.
+//   int? methodAndFieldAndSetter4;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:57:12: Error: Conflicts with the implicit setter of the field 'fieldAndSetter1'.
+//   void set fieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:56:8: Error: Conflicts with setter 'fieldAndSetter1'.
+//   int? fieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:60:12: Error: Conflicts with the implicit setter of the field 'fieldAndSetter2'.
+//   void set fieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:59:8: Error: Conflicts with setter 'fieldAndSetter2'.
+//   int? fieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:64:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter1'.
+//   void set fieldAndFinalFieldAndSetter1(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:62:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter1'.
+//   int? fieldAndFinalFieldAndSetter1;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:68:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter2'.
+//   void set fieldAndFinalFieldAndSetter2(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:67:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter2'.
+//   int? fieldAndFinalFieldAndSetter2;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:70:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter3'.
+//   void set fieldAndFinalFieldAndSetter3(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:71:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter3'.
+//   int? fieldAndFinalFieldAndSetter3;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:74:12: Error: Conflicts with the implicit setter of the field 'fieldAndFinalFieldAndSetter4'.
+//   void set fieldAndFinalFieldAndSetter4(int? value) {}
+//            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:76:8: Error: Conflicts with setter 'fieldAndFinalFieldAndSetter4'.
+//   int? fieldAndFinalFieldAndSetter4;
+//        ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:40:12: Error: 'methodAndFinalFieldAndSetter2' is already declared in this scope.
+//   void set methodAndFinalFieldAndSetter2(int? value) {}
+//            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:39:8: Context: Previous declaration of 'methodAndFinalFieldAndSetter2'.
+//   int? methodAndFinalFieldAndSetter2() {}
+//        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:51:12: Error: 'methodAndSetter1' is already declared in this scope.
+//   void set methodAndSetter1(int? value) {}
+//            ^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:50:8: Context: Previous declaration of 'methodAndSetter1'.
+//   int? methodAndSetter1() {}
+//        ^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:12: Error: 'methodAndSetter2' is already declared in this scope.
+//   int? set methodAndSetter2() {}
+//            ^^^^^^^^^^^^^^^^
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:53:8: Context: Previous declaration of 'methodAndSetter2'.
+//   void methodAndSetter2(int? value) {}
+//        ^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:28: Error: A setter should have exactly one formal parameter.
+//   int? set methodAndSetter2() {}
+//                            ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: Can't use 'methodAndField1' because it is declared more than once.
+//   c.methodAndField1 = c.methodAndField1;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:25: Error: Can't use 'methodAndField1' because it is declared more than once.
+//   c.methodAndField1 = c.methodAndField1;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:25: Error: The getter 'methodAndField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndField1'.
+//   c.methodAndField1 = c.methodAndField1;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: The setter 'methodAndField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField1'.
+//   c.methodAndField1 = c.methodAndField1;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: Can't use 'methodAndField2' because it is declared more than once.
+//   c.methodAndField2 = c.methodAndField2;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:25: Error: Can't use 'methodAndField2' because it is declared more than once.
+//   c.methodAndField2 = c.methodAndField2;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:25: Error: The getter 'methodAndField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndField2'.
+//   c.methodAndField2 = c.methodAndField2;
+//                         ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: The setter 'methodAndField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField2'.
+//   c.methodAndField2 = c.methodAndField2;
+//     ^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: Can't use 'methodAndFinalField1' because it is declared more than once.
+//   c.methodAndFinalField1;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: The getter 'methodAndFinalField1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField1'.
+//   c.methodAndFinalField1;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: Can't use 'methodAndFinalField2' because it is declared more than once.
+//   c.methodAndFinalField2;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: The getter 'methodAndFinalField2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField2'.
+//   c.methodAndFinalField2;
+//     ^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: Can't use 'methodAndFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:34: Error: Can't use 'methodAndFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:34: Error: The getter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter1'.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: The setter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter1'.
+//   c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: Can't use 'methodAndFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:34: Error: Can't use 'methodAndFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:34: Error: The getter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter2'.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: The setter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter2'.
+//   c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: Can't use 'methodAndFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:34: Error: Can't use 'methodAndFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:34: Error: The getter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter3'.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: The setter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter3'.
+//   c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: Can't use 'methodAndFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:34: Error: Can't use 'methodAndFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:34: Error: The getter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFieldAndSetter4'.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//                                  ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: The setter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter4'.
+//   c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: Can't use 'methodAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: The getter 'methodAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter1'.
+//   c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: Can't use 'methodAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: The getter 'methodAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter2'.
+//   c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: Can't use 'methodAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: The getter 'methodAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter3'.
+//   c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: Can't use 'methodAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: The getter 'methodAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter4'.
+//   c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+//                                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:92:26: Error: A value of type 'int? Function()' can't be assigned to a variable of type 'int?'.
+//   c.methodAndSetter1 = c.methodAndSetter1;
+//                          ^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: Can't use 'fieldAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:38: Error: Can't use 'fieldAndFinalFieldAndSetter1' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:38: Error: The getter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter1'.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: The setter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter1'.
+//   c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: Can't use 'fieldAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:38: Error: Can't use 'fieldAndFinalFieldAndSetter2' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:38: Error: The getter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter2'.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: The setter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter2'.
+//   c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: Can't use 'fieldAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:38: Error: Can't use 'fieldAndFinalFieldAndSetter3' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:38: Error: The getter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter3'.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: The setter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter3'.
+//   c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: Can't use 'fieldAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:38: Error: Can't use 'fieldAndFinalFieldAndSetter4' because it is declared more than once.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:38: Error: The getter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing getter, or defining a getter or field named 'fieldAndFinalFieldAndSetter4'.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: The setter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+//  - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+// Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter4'.
+//   c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+//     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:66:14: Error: Final field 'fieldAndFinalFieldAndSetter2' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? fieldAndFinalFieldAndSetter2 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+// pkg/front_end/testcases/nnbd/instance_duplicates.dart:75:14: Error: Final field 'fieldAndFinalFieldAndSetter4' is not initialized.
+// Try to initialize the field in the declaration or in every constructor.
+//   final int? fieldAndFinalFieldAndSetter4 = 0;
+//              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+//
+import self as self;
+import "dart:core" as core;
+
+class Class extends core::Object {
+  field core::int? methodAndField2 = null;
+  final field core::int? methodAndFinalField2 = null;
+  field core::int? methodAndFieldAndSetter2 = null;
+  field core::int? methodAndFieldAndSetter4 = null;
+  final field core::int? methodAndFinalFieldAndSetter2 = null;
+  final field core::int? methodAndFinalFieldAndSetter4 = null;
+  field core::int? fieldAndSetter1 = null;
+  field core::int? fieldAndSetter2 = null;
+  field core::int? fieldAndFinalFieldAndSetter1 = null;
+  final field core::int? fieldAndFinalFieldAndSetter2 = null;
+  field core::int? fieldAndFinalFieldAndSetter3 = null;
+  final field core::int? fieldAndFinalFieldAndSetter4 = null;
+  synthetic constructor •() → self::Class
+    : super core::Object::•()
+    ;
+  method methodAndField1() → core::int? {}
+  method methodAndFinalField1() → core::int? {}
+  method methodAndFieldAndSetter1() → core::int? {}
+  method methodAndFieldAndSetter3() → core::int? {}
+  method methodAndFinalFieldAndSetter1() → core::int? {}
+  set methodAndFinalFieldAndSetter1(core::int? value) → void {}
+  set methodAndFinalFieldAndSetter2(core::int? value) → void {}
+  set methodAndFinalFieldAndSetter3(core::int? value) → void {}
+  method methodAndFinalFieldAndSetter3() → core::int? {}
+  set methodAndFinalFieldAndSetter4(core::int? value) → void {}
+  method methodAndSetter1() → core::int? {}
+  set methodAndSetter1(core::int? value) → void {}
+  method methodAndSetter2(core::int? value) → void {}
+  set methodAndSetter2(dynamic #synthetic) → void {
+    invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:54:28: Error: A setter should have exactly one formal parameter.
+  int? set methodAndSetter2() {}
+                           ^";
+    {}
+  }
+}
+static method test(self::Class c) → dynamic {
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:80:5: Error: The setter 'methodAndField1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField1'.
+  c.methodAndField1 = c.methodAndField1;
+    ^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:81:5: Error: The setter 'methodAndField2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndField2'.
+  c.methodAndField2 = c.methodAndField2;
+    ^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:82:5: Error: The getter 'methodAndFinalField1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField1'.
+  c.methodAndFinalField1;
+    ^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:83:5: Error: The getter 'methodAndFinalField2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalField2'.
+  c.methodAndFinalField2;
+    ^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:84:5: Error: The setter 'methodAndFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter1'.
+  c.methodAndFieldAndSetter1 = c.methodAndFieldAndSetter1;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:85:5: Error: The setter 'methodAndFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter2'.
+  c.methodAndFieldAndSetter2 = c.methodAndFieldAndSetter2;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:86:5: Error: The setter 'methodAndFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter3'.
+  c.methodAndFieldAndSetter3 = c.methodAndFieldAndSetter3;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:87:5: Error: The setter 'methodAndFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'methodAndFieldAndSetter4'.
+  c.methodAndFieldAndSetter4 = c.methodAndFieldAndSetter4;
+    ^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndFinalFieldAndSetter1} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:88:39: Error: The getter 'methodAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter1'.
+  c.methodAndFinalFieldAndSetter1 = c.methodAndFinalFieldAndSetter1;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndFinalFieldAndSetter2} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:89:39: Error: The getter 'methodAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter2'.
+  c.methodAndFinalFieldAndSetter2 = c.methodAndFinalFieldAndSetter2;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndFinalFieldAndSetter3} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:90:39: Error: The getter 'methodAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter3'.
+  c.methodAndFinalFieldAndSetter3 = c.methodAndFinalFieldAndSetter3;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndFinalFieldAndSetter4} = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:91:39: Error: The getter 'methodAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing getter, or defining a getter or field named 'methodAndFinalFieldAndSetter4'.
+  c.methodAndFinalFieldAndSetter4 = c.methodAndFinalFieldAndSetter4;
+                                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  c.{self::Class::methodAndSetter1} = let final<BottomType> #t1 = invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:92:26: Error: A value of type 'int? Function()' can't be assigned to a variable of type 'int?'.
+  c.methodAndSetter1 = c.methodAndSetter1;
+                         ^" in c.{self::Class::methodAndSetter1} as{TypeError,ForNonNullableByDefault} core::int?;
+  c.{self::Class::methodAndSetter2} = c.{self::Class::methodAndSetter2};
+  c.{self::Class::fieldAndSetter1} = c.{self::Class::fieldAndSetter1};
+  c.{self::Class::fieldAndSetter2} = c.{self::Class::fieldAndSetter2};
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:96:5: Error: The setter 'fieldAndFinalFieldAndSetter1' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter1'.
+  c.fieldAndFinalFieldAndSetter1 = c.fieldAndFinalFieldAndSetter1;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:97:5: Error: The setter 'fieldAndFinalFieldAndSetter2' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter2'.
+  c.fieldAndFinalFieldAndSetter2 = c.fieldAndFinalFieldAndSetter2;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:98:5: Error: The setter 'fieldAndFinalFieldAndSetter3' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter3'.
+  c.fieldAndFinalFieldAndSetter3 = c.fieldAndFinalFieldAndSetter3;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+  invalid-expression "pkg/front_end/testcases/nnbd/instance_duplicates.dart:99:5: Error: The setter 'fieldAndFinalFieldAndSetter4' isn't defined for the class 'Class'.
+ - 'Class' is from 'pkg/front_end/testcases/nnbd/instance_duplicates.dart'.
+Try correcting the name to the name of an existing setter, or defining a setter or field named 'fieldAndFinalFieldAndSetter4'.
+  c.fieldAndFinalFieldAndSetter4 = c.fieldAndFinalFieldAndSetter4;
+    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^";
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.outline.expect b/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.outline.expect
index df32287..f837d5e 100644
--- a/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.outline.expect
+++ b/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.outline.expect
@@ -20,14 +20,14 @@
 // void set topLevelMethodAndSetter(value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:5:1: Error: Conflicts with setter 'topLevelMethodAndSetter'.
-// topLevelMethodAndSetter() {}
-// ^
-//
 // pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:6:10: Error: Conflicts with member 'topLevelMethodAndSetter'.
 // void set topLevelMethodAndSetter(value) {}
 //          ^
 //
+// pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:5:1: Error: Conflicts with setter 'topLevelMethodAndSetter'.
+// topLevelMethodAndSetter() {}
+// ^
+//
 // pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:13:10: Error: Conflicts with member 'classAndSetter'.
 // void set classAndSetter(value) {}
 //          ^
diff --git a/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.strong.expect b/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.strong.expect
index d586281..5582fac 100644
--- a/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.strong.expect
@@ -20,14 +20,14 @@
 // void set topLevelMethodAndSetter(value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:5:1: Error: Conflicts with setter 'topLevelMethodAndSetter'.
-// topLevelMethodAndSetter() {}
-// ^
-//
 // pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:6:10: Error: Conflicts with member 'topLevelMethodAndSetter'.
 // void set topLevelMethodAndSetter(value) {}
 //          ^
 //
+// pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:5:1: Error: Conflicts with setter 'topLevelMethodAndSetter'.
+// topLevelMethodAndSetter() {}
+// ^
+//
 // pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:13:10: Error: Conflicts with member 'classAndSetter'.
 // void set classAndSetter(value) {}
 //          ^
diff --git a/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.strong.transformed.expect b/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.strong.transformed.expect
index d586281..5582fac 100644
--- a/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.strong.transformed.expect
@@ -20,14 +20,14 @@
 // void set topLevelMethodAndSetter(value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:5:1: Error: Conflicts with setter 'topLevelMethodAndSetter'.
-// topLevelMethodAndSetter() {}
-// ^
-//
 // pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:6:10: Error: Conflicts with member 'topLevelMethodAndSetter'.
 // void set topLevelMethodAndSetter(value) {}
 //          ^
 //
+// pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:5:1: Error: Conflicts with setter 'topLevelMethodAndSetter'.
+// topLevelMethodAndSetter() {}
+// ^
+//
 // pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:13:10: Error: Conflicts with member 'classAndSetter'.
 // void set classAndSetter(value) {}
 //          ^
diff --git a/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.weak.expect b/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.weak.expect
index d586281..5582fac 100644
--- a/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.weak.expect
@@ -20,14 +20,14 @@
 // void set topLevelMethodAndSetter(value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:5:1: Error: Conflicts with setter 'topLevelMethodAndSetter'.
-// topLevelMethodAndSetter() {}
-// ^
-//
 // pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:6:10: Error: Conflicts with member 'topLevelMethodAndSetter'.
 // void set topLevelMethodAndSetter(value) {}
 //          ^
 //
+// pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:5:1: Error: Conflicts with setter 'topLevelMethodAndSetter'.
+// topLevelMethodAndSetter() {}
+// ^
+//
 // pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:13:10: Error: Conflicts with member 'classAndSetter'.
 // void set classAndSetter(value) {}
 //          ^
diff --git a/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.weak.transformed.expect b/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.weak.transformed.expect
index d586281..5582fac 100644
--- a/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart.weak.transformed.expect
@@ -20,14 +20,14 @@
 // void set topLevelMethodAndSetter(value) {}
 //          ^
 //
-// pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:5:1: Error: Conflicts with setter 'topLevelMethodAndSetter'.
-// topLevelMethodAndSetter() {}
-// ^
-//
 // pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:6:10: Error: Conflicts with member 'topLevelMethodAndSetter'.
 // void set topLevelMethodAndSetter(value) {}
 //          ^
 //
+// pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:5:1: Error: Conflicts with setter 'topLevelMethodAndSetter'.
+// topLevelMethodAndSetter() {}
+// ^
+//
 // pkg/front_end/testcases/nnbd/nonfield_vs_setter.dart:13:10: Error: Conflicts with member 'classAndSetter'.
 // void set classAndSetter(value) {}
 //          ^
diff --git a/runtime/bin/process_win.cc b/runtime/bin/process_win.cc
index 26d7d0b..8edd8dd 100644
--- a/runtime/bin/process_win.cc
+++ b/runtime/bin/process_win.cc
@@ -564,7 +564,6 @@
         reinterpret_cast<STARTUPINFOW*>(&startup_info), &process_info);
 
     if (result == 0) {
-      Syslog::PrintErr("CreateProcessW failed %d\n", GetLastError());
       return CleanupAndReturnError();
     }
 
diff --git a/runtime/vm/BUILD.gn b/runtime/vm/BUILD.gn
index 49c4036..93534de 100644
--- a/runtime/vm/BUILD.gn
+++ b/runtime/vm/BUILD.gn
@@ -74,7 +74,7 @@
   if (is_fuchsia) {
     if (using_fuchsia_gn_sdk) {
       extra_deps = [
-        "$fuchsia_sdk_root/fidl/fuchsia.intl",
+        "$fuchsia_sdk_root/fidl/fuchsia.deprecatedtimezone",
         "$fuchsia_sdk_root/pkg/async",
         "$fuchsia_sdk_root/pkg/async-default",
         "$fuchsia_sdk_root/pkg/async-loop",
@@ -87,7 +87,7 @@
       ]
     } else if (using_fuchsia_sdk) {
       extra_deps = [
-        "$fuchsia_sdk_root/fidl:fuchsia.intl",
+        "$fuchsia_sdk_root/fidl:fuchsia.deprecatedtimezone",
         "$fuchsia_sdk_root/pkg:async-loop",
         "$fuchsia_sdk_root/pkg:async-loop-default",
         "$fuchsia_sdk_root/pkg:inspect",
@@ -98,7 +98,9 @@
       ]
     } else {
       extra_deps = [
-        "//sdk/fidl/fuchsia.intl",
+        # TODO(US-399): Remove time_service specific code when it is no longer
+        # necessary.
+        "//sdk/fidl/fuchsia.deprecatedtimezone",
         "//sdk/lib/sys/cpp",
         "//sdk/lib/sys/inspect/cpp",
         "//zircon/public/lib/fbl",
diff --git a/runtime/vm/os_fuchsia.cc b/runtime/vm/os_fuchsia.cc
index a9bee8e..e79827b 100644
--- a/runtime/vm/os_fuchsia.cc
+++ b/runtime/vm/os_fuchsia.cc
@@ -10,10 +10,8 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <stdint.h>
-#include <string.h>
-#include <unistd.h>
 
-#include <fuchsia/intl/cpp/fidl.h>
+#include <fuchsia/deprecatedtimezone/cpp/fidl.h>
 #include <lib/async-loop/default.h>
 #include <lib/async-loop/loop.h>
 #include <lib/async/default.h>
@@ -24,49 +22,21 @@
 #include <zircon/process.h>
 #include <zircon/syscalls.h>
 #include <zircon/syscalls/object.h>
-#include <zircon/threads.h>
 #include <zircon/time.h>
+#include <zircon/threads.h>
 #include <zircon/types.h>
 
-#include <set>
-
-#include "unicode/errorcode.h"
-#include "unicode/timezone.h"
-#include "unicode/umachine.h"
-
 #include "platform/assert.h"
-#include "platform/syslog.h"
 #include "platform/utils.h"
-#include "vm/lockers.h"
-#include "vm/os_thread.h"
 #include "vm/zone.h"
 
 namespace {
 
-using dart::Mutex;
-using dart::MutexLocker;
-using dart::Syslog;
-using dart::Zone;
-
-// This is the default timezone returned if it could not be obtained.  For
-// Fuchsia, the default device timezone is always UTC.
-static const char kDefaultTimezone[] = "UTC";
-
-static constexpr int32_t kMsPerSec = 1000;
-
 // The data directory containing ICU timezone data files.
 static constexpr char kICUTZDataDir[] = "/config/data/tzdata/icu/44/le";
 
-// This is the general OK status.
-static constexpr int32_t kOk = 0;
-
-// This status means that the error code is not initialized yet ("set" was not
-// yet called).  Error codes are usually either 0 (kOk), or negative.
-static constexpr int32_t kUninitialized = 1;
-
 // The status codes for tzdata file open and read.
 enum class TZDataStatus {
-  // The operation completed without error.
   OK = 0,
   // The open call for the tzdata file did not succeed.
   COULD_NOT_OPEN = -1,
@@ -76,8 +46,6 @@
 
 // Adds a facility for introspecting timezone data errors.  Allows insight into
 // the internal state of the VM even if error reporting facilities fail.
-//
-// Under normal operation, all metric values below should be zero.
 class InspectMetrics {
  public:
   // Does not take ownership of inspector.
@@ -85,27 +53,9 @@
       : inspector_(inspector),
         root_(inspector_->GetRoot()),
         metrics_(root_.CreateChild("os")),
-        dst_status_(metrics_.CreateInt("dst_status", kUninitialized)),
-        tz_data_status_(metrics_.CreateInt("tz_data_status", kUninitialized)),
-        tz_data_close_status_(
-            metrics_.CreateInt("tz_data_close_status", kUninitialized)),
-        get_profile_status_(
-            metrics_.CreateInt("get_profile_status", kUninitialized)),
-        profiles_timezone_content_status_(
-            metrics_.CreateInt("timezone_content_status", kOk)),
-        num_get_profile_calls_(metrics_.CreateInt("num_get_profile_calls", 0)),
-        num_on_change_calls_(metrics_.CreateInt("num_on_change_calls", 0)),
-        num_intl_provider_errors_(
-            metrics_.CreateInt("num_intl_provider_errors", 0)) {}
-
-  // Registers a single call to GetProfile callback.
-  void RegisterGetProfileCall() { num_get_profile_calls_.Add(1); }
-
-  // Registers a single call to OnChange callback.
-  void RegisterOnChangeCall() { num_on_change_calls_.Add(1); }
-
-  // Registers a provider error.
-  void RegisterIntlProviderError() { num_intl_provider_errors_.Add(1); }
+        dst_status_(metrics_.CreateInt("dst_status", 0)),
+        tz_data_status_(metrics_.CreateInt("tz_data_status", 0)),
+        tz_data_close_status_(metrics_.CreateInt("tz_data_close_status", 0)) {}
 
   // Sets the last status code for DST offset calls.
   void SetDSTOffsetStatus(zx_status_t status) {
@@ -119,17 +69,6 @@
     tz_data_close_status_.Set(status);
   }
 
-  // Sets the last status code for the call to PropertyProvider::GetProfile.
-  void SetProfileStatus(zx_status_t status) {
-    get_profile_status_.Set(static_cast<int32_t>(status));
-  }
-
-  // Sets the last status seen while examining timezones returned from
-  // PropertyProvider::GetProfile.
-  void SetTimeZoneContentStatus(zx_status_t status) {
-    profiles_timezone_content_status_.Set(static_cast<int32_t>(status));
-  }
-
  private:
   // The inspector that all metrics are being reported into.
   inspect::Inspector* inspector_;
@@ -148,165 +87,11 @@
 
   // The return code for the close() call for tzdata files.
   inspect::IntProperty tz_data_close_status_;
-
-  // The return code of the GetProfile call in GetTimeZoneName.  If this is
-  // nonzero, then os_fuchsia.cc reported a default timezone as a fallback.
-  inspect::IntProperty get_profile_status_;
-
-  // U_ILLEGAL_ARGUMENT_ERROR(=1) if timezones read from ProfileProvider were
-  // incorrect. Otherwise 0.  If this metric reports U_ILLEGAL_ARGUMENT_ERROR,
-  // the os_fuchsia.cc module reported a default timezone as a fallback.
-  inspect::IntProperty profiles_timezone_content_status_;
-
-  // Keeps a number of get_profile update calls.
-  inspect::IntProperty num_get_profile_calls_;
-
-  // Number of "on change" callback calls.
-  inspect::IntProperty num_on_change_calls_;
-
-  // Keeps a number of errors encountered in intl provider.
-  inspect::IntProperty num_intl_provider_errors_;
 };
 
-// Thread-safe storage for the current timezone name.
-//
-// Keeps an up to date timezone cache, updating if needed through the
-// asynchronous update interface.  Access to this class is thread-safe.
-class TimezoneName final {
- public:
-  // Creates a new instance of TimezoneName.  Does not take ownership of
-  // metrics.
-  static std::shared_ptr<TimezoneName> New(
-      fuchsia::intl::PropertyProviderPtr proxy,
-      std::weak_ptr<InspectMetrics> metrics) {
-    auto timezone_name =
-        std::make_shared<TimezoneName>(std::move(proxy), metrics);
-    timezone_name->InitHandlers(timezone_name);
-    return timezone_name;
-  }
-
-  TimezoneName(fuchsia::intl::PropertyProviderPtr proxy,
-               std::weak_ptr<InspectMetrics> metrics)
-      : m_(),
-        metrics_(std::move(metrics)),
-        proxy_(std::move(proxy)),
-        timezone_name_(kDefaultTimezone) {
-    ASSERT(metrics_.lock() != nullptr);
-  }
-
-  // Gets the current timezone name.  Repeated calls may retrieve updated
-  // values.
-  std::string Get() const {
-    MutexLocker lock(&m_);
-    // Returns a copy, to avoid a data race with async updates.
-    return timezone_name_;
-  }
-
- private:
-  // Sets the event handlers in this resolver.  Intended to resolve a circular
-  // reference between the shared timezone name and this.
-  void InitHandlers(std::shared_ptr<TimezoneName> timezone_name) {
-    ASSERT(timezone_name.get() == this);
-    timezone_name->proxy_.set_error_handler(
-        [weak_this = std::weak_ptr(timezone_name)](zx_status_t status) {
-          if (!weak_this.expired()) {
-            weak_this.lock()->ErrorHandler(status);
-          }
-        });
-    timezone_name->proxy_.events().OnChange =
-        [weak_this = std::weak_ptr(timezone_name)]() {
-          if (!weak_this.expired()) {
-            weak_this.lock()->OnChangeCallback();
-          }
-        };
-    timezone_name->proxy_->GetProfile(
-        [weak_this =
-             std::weak_ptr(timezone_name)](fuchsia::intl::Profile profile) {
-          if (!weak_this.expired()) {
-            weak_this.lock()->GetProfileCallback(std::move(profile));
-          }
-        });
-  }
-
-  // Called on a profile provider error in the context of the event loop
-  // thread.
-  void ErrorHandler(zx_status_t status) {
-    MutexLocker lock(&m_);
-    WithMetrics([status](std::shared_ptr<InspectMetrics> metrics) {
-      metrics->SetProfileStatus(status);
-      metrics->RegisterIntlProviderError();
-    });
-  }
-
-  // Called when an OnChange event is received in the context of the event loop
-  // thread.  The only action here is to trigger an asynchronous update of the
-  // intl profile.
-  void OnChangeCallback() {
-    MutexLocker lock(&m_);
-    WithMetrics([](std::shared_ptr<InspectMetrics> metrics) {
-      metrics->RegisterOnChangeCall();
-    });
-    proxy_->GetProfile([this](fuchsia::intl::Profile profile) {
-      this->GetProfileCallback(std::move(profile));
-    });
-  }
-
-  // Called when a GetProfile async request is resolved, in the context of the
-  // event loop thread.
-  void GetProfileCallback(fuchsia::intl::Profile profile) {
-    MutexLocker lock(&m_);
-    WithMetrics([](std::shared_ptr<InspectMetrics> metrics) {
-      metrics->RegisterGetProfileCall();
-    });
-    const std::vector<fuchsia::intl::TimeZoneId>& timezones =
-        profile.time_zones();
-    if (timezones.empty()) {
-      WithMetrics([](std::shared_ptr<InspectMetrics> metrics) {
-        metrics->SetTimeZoneContentStatus(U_ILLEGAL_ARGUMENT_ERROR);
-      });
-      // Empty timezone array is not up to fuchsia::intl spec.  The serving
-      // endpoint is broken and should be fixed.
-      Syslog::PrintErr("got empty timezone value\n");
-      return;
-    }
-    WithMetrics([](std::shared_ptr<InspectMetrics> metrics) {
-      metrics->SetProfileStatus(ZX_OK);
-      metrics->SetTimeZoneContentStatus(ZX_OK);
-    });
-
-    timezone_name_ = timezones[0].id;
-  }
-
-  // Runs the provided function only on valid metrics.
-  void WithMetrics(std::function<void(std::shared_ptr<InspectMetrics> m)> f) {
-    std::shared_ptr<InspectMetrics> l = metrics_.lock();
-    if (l != nullptr) {
-      f(l);
-    }
-  }
-
-  // Guards timezone_name_ because the callbacks will be called in an
-  // asynchronous thread.
-  mutable Mutex m_;
-
-  // Used to keep tally on the update events. Not owned.
-  std::weak_ptr<InspectMetrics> metrics_;
-
-  // A client-side proxy for a connection to the property provider service.
-  fuchsia::intl::PropertyProviderPtr proxy_;
-
-  // Caches the current timezone name.  This is updated asynchronously through
-  // GetProfileCallback.
-  std::string timezone_name_;
-};
-
-// The timezone names encountered so far.  The timezone names must live forever.
-std::set<const std::string> timezone_names;
-
 // Initialized on OS:Init(), deinitialized on OS::Cleanup.
 std::unique_ptr<sys::ComponentInspector> component_inspector;
-std::shared_ptr<InspectMetrics> metrics;
-std::shared_ptr<TimezoneName> timezone_name;
+std::unique_ptr<InspectMetrics> metrics;
 async_loop_t* message_loop = nullptr;
 
 // Initializes the source of timezone data if available.  Timezone data file in
@@ -368,57 +153,35 @@
 // Putting this hack right now due to CP-120 as I need to remove
 // component:ConnectToEnvironmentServices and this is the only thing that is
 // blocking it and FL-98 will take time.
-static fuchsia::intl::PropertyProviderPtr property_provider;
+static fuchsia::deprecatedtimezone::TimezoneSyncPtr tz;
 
 static zx_status_t GetLocalAndDstOffsetInSeconds(int64_t seconds_since_epoch,
                                                  int32_t* local_offset,
                                                  int32_t* dst_offset) {
-  const char* timezone_id = OS::GetTimeZoneName(seconds_since_epoch);
-  std::unique_ptr<icu::TimeZone> timezone(
-      icu::TimeZone::createTimeZone(timezone_id));
-  UErrorCode error = U_ZERO_ERROR;
-  const auto ms_since_epoch =
-      static_cast<UDate>(kMsPerSec * seconds_since_epoch);
-  // The units of time that local_offset and dst_offset are returned from this
-  // function is, usefully, not documented, but it seems that the units are
-  // milliseconds.  Add these variables here for clarity.
-  int32_t local_offset_ms = 0;
-  int32_t dst_offset_ms = 0;
-  timezone->getOffset(ms_since_epoch, /*local_time=*/0, local_offset_ms,
-                      dst_offset_ms, error);
-  metrics->SetDSTOffsetStatus(error);
-  if (error != U_ZERO_ERROR) {
-    icu::ErrorCode icu_error;
-    icu_error.set(error);
-    Syslog::PrintErr("could not get DST offset: %s\n", icu_error.errorName());
-    return ZX_ERR_INTERNAL;
+  zx_status_t status = tz->GetTimezoneOffsetMinutes(seconds_since_epoch * 1000,
+                                                    local_offset, dst_offset);
+  metrics->SetDSTOffsetStatus(status);
+  if (status != ZX_OK) {
+    return status;
   }
-  // We must return offset in seconds, so convert.
-  *local_offset = local_offset_ms / kMsPerSec;
-  *dst_offset = dst_offset_ms / kMsPerSec;
+  *local_offset *= 60;
+  *dst_offset *= 60;
   return ZX_OK;
 }
 
-// Returns a C string with the time zone name. This module retains the
-// ownership of the pointer.
 const char* OS::GetTimeZoneName(int64_t seconds_since_epoch) {
-  ASSERT(timezone_name != nullptr);
-
-  // Sadly, since we do not know how long the timezone name will be needed, we
-  // can not ever deallocate it. So instead, we put it into a a set that will
-  // not move it around in memory and return a pointer to it.  Since the number
-  // of timezones is finite, this ensures that the memory taken up by timezones
-  // does not grow indefinitely, even if we end up retaining all the timezones
-  // there are.
-  const auto i = timezone_names.insert(timezone_name->Get());
-  ASSERT(i.first != timezone_names.end());
-  return i.first->c_str();
+  // TODO(abarth): Handle time zone changes.
+  static const auto* tz_name = new std::string([] {
+    std::string result;
+    tz->GetTimezoneId(&result);
+    return result;
+  }());
+  return tz_name->c_str();
 }
 
 int OS::GetTimeZoneOffsetInSeconds(int64_t seconds_since_epoch) {
-  int32_t local_offset = 0;
-  int32_t dst_offset = 0;
-  const zx_status_t status = GetLocalAndDstOffsetInSeconds(
+  int32_t local_offset, dst_offset;
+  zx_status_t status = GetLocalAndDstOffsetInSeconds(
       seconds_since_epoch, &local_offset, &dst_offset);
   return status == ZX_OK ? local_offset + dst_offset : 0;
 }
@@ -448,7 +211,7 @@
 }
 
 int64_t OS::GetCurrentMonotonicMicros() {
-  const int64_t ticks = GetCurrentMonotonicTicks();
+  int64_t ticks = GetCurrentMonotonicTicks();
   ASSERT(GetCurrentMonotonicFrequency() == kNanosecondsPerSecond);
   return ticks / kNanosecondsPerMicrosecond;
 }
@@ -468,9 +231,6 @@
   return -1;
 }
 
-// The timezone names encountered so far.  The timezone names must live forever.
-std::set<const std::string> timezone_names;
-
 // TODO(5411554):  May need to hoist these architecture dependent code
 // into a architecture specific file e.g: os_ia32_fuchsia.cc
 intptr_t OS::ActivationFrameAlignment() {
@@ -540,7 +300,7 @@
   va_end(measure_args);
 
   char* buffer;
-  if (zone != nullptr) {
+  if (zone) {
     buffer = zone->Alloc<char>(len + 1);
   } else {
     buffer = reinterpret_cast<char*>(malloc(len + 1));
@@ -604,22 +364,19 @@
 
   sys::ComponentContext* context = dart::ComponentContext();
   component_inspector = std::make_unique<sys::ComponentInspector>(context);
-  metrics = std::make_shared<InspectMetrics>(component_inspector->inspector());
+  metrics = std::make_unique<InspectMetrics>(component_inspector->inspector());
 
   InitializeTZData();
-  auto services = sys::ServiceDirectory::CreateFromNamespace();
-  services->Connect(property_provider.NewRequest());
-
-  timezone_name = TimezoneName::New(std::move(property_provider), metrics);
+  context->svc()->Connect(tz.NewRequest());
 }
 
 void OS::Cleanup() {
   if (message_loop != nullptr) {
     async_loop_shutdown(message_loop);
   }
-  timezone_name.reset();
-  metrics.reset();
-  component_inspector.reset();
+
+  metrics = nullptr;
+  component_inspector = nullptr;
 
   if (message_loop != nullptr) {
     // Check message_loop is still the default dispatcher before clearing it.
diff --git a/tests/language/extension_methods/static_extension_internal_name_conflict_error_test.dart b/tests/language/extension_methods/static_extension_internal_name_conflict_error_test.dart
index 21277b5..f19b8e8 100644
--- a/tests/language/extension_methods/static_extension_internal_name_conflict_error_test.dart
+++ b/tests/language/extension_methods/static_extension_internal_name_conflict_error_test.dart
@@ -58,6 +58,8 @@
   static void set property(int value) {}
   static int field = 3;
   static int field2 = 4;
+  //         ^
+  // [cfe] Conflicts with setter 'field2'.
 
   static int method() => 0;
   //         ^^^^^^
@@ -82,6 +84,7 @@
   static void set field2(int value) {}
   //              ^^^^^^
   // [analyzer] COMPILE_TIME_ERROR.DUPLICATE_DEFINITION
+  // [cfe] Conflicts with the implicit setter of the field 'field2'.
 }
 
 // Check instance members colliding with instance members (of the same kind).
@@ -112,6 +115,7 @@
   static int get property => 1;
   //             ^^^^^^^^
   // [analyzer] COMPILE_TIME_ERROR.EXTENSION_CONFLICTING_STATIC_AND_INSTANCE
+  // [cfe] Conflicts with setter 'property'.
   static void set property(int value) {}
   //              ^^^^^^^^
   // [analyzer] COMPILE_TIME_ERROR.EXTENSION_CONFLICTING_STATIC_AND_INSTANCE
@@ -143,6 +147,8 @@
   void set property(int value) {}
   //       ^
   // [cfe] 'property' is already declared in this scope.
+  //       ^
+  // [cfe] Conflicts with member 'property'.
   void set property2(int value) {}
   //       ^
   // [cfe] Conflicts with member 'property2'.
diff --git a/tests/language_2/extension_methods/static_extension_internal_name_conflict_error_test.dart b/tests/language_2/extension_methods/static_extension_internal_name_conflict_error_test.dart
index 21277b5..f19b8e8 100644
--- a/tests/language_2/extension_methods/static_extension_internal_name_conflict_error_test.dart
+++ b/tests/language_2/extension_methods/static_extension_internal_name_conflict_error_test.dart
@@ -58,6 +58,8 @@
   static void set property(int value) {}
   static int field = 3;
   static int field2 = 4;
+  //         ^
+  // [cfe] Conflicts with setter 'field2'.
 
   static int method() => 0;
   //         ^^^^^^
@@ -82,6 +84,7 @@
   static void set field2(int value) {}
   //              ^^^^^^
   // [analyzer] COMPILE_TIME_ERROR.DUPLICATE_DEFINITION
+  // [cfe] Conflicts with the implicit setter of the field 'field2'.
 }
 
 // Check instance members colliding with instance members (of the same kind).
@@ -112,6 +115,7 @@
   static int get property => 1;
   //             ^^^^^^^^
   // [analyzer] COMPILE_TIME_ERROR.EXTENSION_CONFLICTING_STATIC_AND_INSTANCE
+  // [cfe] Conflicts with setter 'property'.
   static void set property(int value) {}
   //              ^^^^^^^^
   // [analyzer] COMPILE_TIME_ERROR.EXTENSION_CONFLICTING_STATIC_AND_INSTANCE
@@ -143,6 +147,8 @@
   void set property(int value) {}
   //       ^
   // [cfe] 'property' is already declared in this scope.
+  //       ^
+  // [cfe] Conflicts with member 'property'.
   void set property2(int value) {}
   //       ^
   // [cfe] Conflicts with member 'property2'.
diff --git a/tools/VERSION b/tools/VERSION
index 1f6d95e..4eba935 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -27,5 +27,5 @@
 MAJOR 2
 MINOR 13
 PATCH 0
-PRERELEASE 43
+PRERELEASE 44
 PRERELEASE_PATCH 0
\ No newline at end of file