diff --git a/pkg/_fe_analyzer_shared/test/flow_analysis/why_not_promoted/data/nullable_error_scenarios.dart b/pkg/_fe_analyzer_shared/test/flow_analysis/why_not_promoted/data/nullable_error_scenarios.dart
new file mode 100644
index 0000000..5797fa4
--- /dev/null
+++ b/pkg/_fe_analyzer_shared/test/flow_analysis/why_not_promoted/data/nullable_error_scenarios.dart
@@ -0,0 +1,82 @@
+// Copyright (c) 2020, 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.
+
+// This test contains a test case for each kind of error that can arise from an
+// expression being nullable, for which we wish to report "why not promoted"
+// errors.
+
+class C {
+  int? i;
+  void Function()? f;
+}
+
+extension on int {
+  get propertyOnNonNullInt => null;
+  void methodOnNonNullInt() {}
+}
+
+extension on int? {
+  get propertyOnNullableInt => null;
+  void methodOnNullableInt() {}
+}
+
+property_get_of_variable(int? i, int? j) {
+  if (i == null) return;
+  /*cfe.update: explicitWrite*/ /*analyzer.explicitWrite*/ i = j;
+  i. /*notPromoted(explicitWrite)*/ isEven;
+}
+
+extension_property_get_of_variable(int? i, int? j) {
+  if (i == null) return;
+  /*cfe.update: explicitWrite*/ /*analyzer.explicitWrite*/ i = j;
+  i.propertyOnNullableInt;
+  i.
+      /*cfe.invoke: notPromoted(explicitWrite)*/
+      /*analyzer.notPromoted(explicitWrite)*/
+      propertyOnNonNullInt;
+}
+
+property_get_of_expression(C c) {
+  if (c.i == null) return;
+  c.i. /*notPromoted(propertyNotPromoted(member:C.i))*/ isEven;
+}
+
+extension_property_get_of_expression(C c) {
+  if (c.i == null) return;
+  c.i.propertyOnNullableInt;
+  c
+      .i
+      .
+      /*cfe.invoke: notPromoted(propertyNotPromoted(member:C.i))*/
+      /*analyzer.notPromoted(propertyNotPromoted(member:C.i))*/
+      propertyOnNonNullInt;
+}
+
+method_invocation(C c) {
+  if (c.i == null) return;
+  c.i
+      .
+      /*cfe.invoke: notPromoted(propertyNotPromoted(member:C.i))*/
+      /*analyzer.notPromoted(propertyNotPromoted(member:C.i))*/
+      abs();
+}
+
+extension_method_invocation(C c) {
+  if (c.i == null) return;
+  c.i.methodOnNullableInt();
+  c.i
+      .
+      /*cfe.invoke: notPromoted(propertyNotPromoted(member:C.i))*/
+      /*analyzer.notPromoted(propertyNotPromoted(member:C.i))*/
+      methodOnNonNullInt();
+}
+
+call_invocation(C c) {
+  if (c.f == null) return;
+  c.f
+      .
+      /*cfe.invoke: notPromoted(propertyNotPromoted(member:C.f))*/
+      /*analyzer.notPromoted(propertyNotPromoted(member:C.f))*/
+      call();
+}
diff --git a/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart b/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
index 81efd86..4ad0b97 100644
--- a/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/inference_visitor.dart
@@ -5,13 +5,9 @@
 // @dart = 2.9
 
 import 'dart:core' hide MapEntry;
-import 'dart:core' as core;
 
-import 'package:_fe_analyzer_shared/src/flow_analysis/flow_analysis.dart';
-import 'package:_fe_analyzer_shared/src/testing/id.dart';
 import 'package:_fe_analyzer_shared/src/util/link.dart';
 import 'package:front_end/src/api_prototype/lowering_predicates.dart';
-import 'package:front_end/src/testing/id_extractor.dart';
 import 'package:kernel/ast.dart'
     hide Reference; // Work around https://github.com/dart-lang/sdk/issues/44667
 import 'package:kernel/src/legacy_erasure.dart';
@@ -4739,36 +4735,13 @@
 
     readResult ??= new ExpressionInferenceResult(readType, read);
     if (!inferrer.isTopLevel && readTarget.isNullable) {
-      Map<DartType, NonPromotionReason> whyNotPromoted =
-          inferrer.flowAnalysis?.whyNotPromoted(receiver);
-      List<LocatedMessage> context;
-      if (whyNotPromoted != null && whyNotPromoted.isNotEmpty) {
-        _WhyNotPromotedVisitor whyNotPromotedVisitor =
-            new _WhyNotPromotedVisitor(inferrer, receiver);
-        for (core.MapEntry<DartType, NonPromotionReason> entry
-            in whyNotPromoted.entries) {
-          if (entry.key.isPotentiallyNullable) continue;
-          LocatedMessage message = entry.value.accept(whyNotPromotedVisitor);
-          if (inferrer.dataForTesting != null) {
-            String nonPromotionReasonText = entry.value.shortName;
-            if (whyNotPromotedVisitor.propertyReference != null) {
-              Id id = computeMemberId(whyNotPromotedVisitor.propertyReference);
-              nonPromotionReasonText += '($id)';
-            }
-            inferrer.dataForTesting.flowAnalysisResult
-                .nonPromotionReasons[read] = nonPromotionReasonText;
-          }
-          context = [message];
-          break;
-        }
-      }
       readResult = inferrer.wrapExpressionInferenceResultInProblem(
           readResult,
           templateNullablePropertyAccessError.withArguments(
               propertyName.text, receiverType, inferrer.isNonNullableByDefault),
           read.fileOffset,
           propertyName.text.length,
-          context: context);
+          context: inferrer.getWhyNotPromotedContext(receiver, read));
     }
     return readResult;
   }
@@ -6988,66 +6961,6 @@
   }
 }
 
-class _WhyNotPromotedVisitor
-    implements
-        NonPromotionReasonVisitor<LocatedMessage, Node, Expression,
-            VariableDeclaration> {
-  final TypeInferrerImpl inferrer;
-
-  final Expression receiver;
-
-  Member propertyReference;
-
-  _WhyNotPromotedVisitor(this.inferrer, this.receiver);
-
-  @override
-  LocatedMessage visitDemoteViaExplicitWrite(
-      DemoteViaExplicitWrite<VariableDeclaration, Expression> reason) {
-    if (inferrer.dataForTesting != null) {
-      inferrer.dataForTesting.flowAnalysisResult
-          .nonPromotionReasonTargets[reason.writeExpression] = reason.shortName;
-    }
-    int offset = reason.writeExpression.fileOffset;
-    return templateVariableCouldBeNullDueToWrite
-        .withArguments(reason.variable.name)
-        .withLocation(inferrer.helper.uri, offset, noLength);
-  }
-
-  @override
-  LocatedMessage visitDemoteViaForEachVariableWrite(
-      DemoteViaForEachVariableWrite<VariableDeclaration, Node> reason) {
-    int offset = (reason.node as TreeNode).fileOffset;
-    return templateVariableCouldBeNullDueToWrite
-        .withArguments(reason.variable.name)
-        .withLocation(inferrer.helper.uri, offset, noLength);
-  }
-
-  @override
-  LocatedMessage visitPropertyNotPromoted(PropertyNotPromoted reason) {
-    Member member;
-    Expression receiver = this.receiver;
-    if (receiver is InstanceGet) {
-      member = receiver.interfaceTarget;
-    } else if (receiver is SuperPropertyGet) {
-      member = receiver.interfaceTarget;
-    } else if (receiver is StaticInvocation) {
-      member = receiver.target;
-    } else if (receiver is PropertyGet) {
-      member = receiver.interfaceTarget;
-    } else {
-      assert(false, 'Unrecognized receiver: ${receiver.runtimeType}');
-    }
-    if (member != null) {
-      propertyReference = member;
-      return templateFieldNotPromoted
-          .withArguments(reason.propertyName)
-          .withLocation(member.fileUri, member.fileOffset, noLength);
-    } else {
-      return null;
-    }
-  }
-}
-
 class ForInResult {
   final VariableDeclaration variable;
   final Expression iterable;
diff --git a/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart b/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
index b98da53..3521770 100644
--- a/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
+++ b/pkg/front_end/lib/src/fasta/type_inference/type_inferrer.dart
@@ -5,14 +5,17 @@
 // @dart = 2.9
 
 import 'dart:core' hide MapEntry;
+import 'dart:core' as core;
 
 import 'package:_fe_analyzer_shared/src/flow_analysis/flow_analysis.dart'
     hide Reference; // Work around https://github.com/dart-lang/sdk/issues/44667
 
+import 'package:_fe_analyzer_shared/src/testing/id.dart';
 import 'package:_fe_analyzer_shared/src/util/link.dart';
 
 import 'package:front_end/src/fasta/kernel/internal_ast.dart';
 import 'package:front_end/src/fasta/type_inference/type_demotion.dart';
+import 'package:front_end/src/testing/id_extractor.dart';
 
 import 'package:kernel/ast.dart'
     hide Reference; // Work around https://github.com/dart-lang/sdk/issues/44667
@@ -301,6 +304,37 @@
       ..fileOffset = fileOffset;
   }
 
+  /// Computes a list of context messages explaining why [receiver] was not
+  /// promoted, to be used when reporting an error for a larger expression
+  /// containing [receiver].  [expression] is the containing expression.
+  List<LocatedMessage> getWhyNotPromotedContext(
+      Expression receiver, Expression expression) {
+    Map<DartType, NonPromotionReason> whyNotPromoted =
+        flowAnalysis?.whyNotPromoted(receiver);
+    List<LocatedMessage> context;
+    if (whyNotPromoted != null && whyNotPromoted.isNotEmpty) {
+      _WhyNotPromotedVisitor whyNotPromotedVisitor =
+          new _WhyNotPromotedVisitor(this, receiver);
+      for (core.MapEntry<DartType, NonPromotionReason> entry
+          in whyNotPromoted.entries) {
+        if (entry.key.isPotentiallyNullable) continue;
+        LocatedMessage message = entry.value.accept(whyNotPromotedVisitor);
+        if (dataForTesting != null) {
+          String nonPromotionReasonText = entry.value.shortName;
+          if (whyNotPromotedVisitor.propertyReference != null) {
+            Id id = computeMemberId(whyNotPromotedVisitor.propertyReference);
+            nonPromotionReasonText += '($id)';
+          }
+          dataForTesting.flowAnalysisResult.nonPromotionReasons[expression] =
+              nonPromotionReasonText;
+        }
+        context = [message];
+        break;
+      }
+    }
+    return context;
+  }
+
   /// Returns `true` if exceptions should be thrown in paths reachable only due
   /// to unsoundness in flow analysis in mixed mode.
   bool get shouldThrowUnsoundnessException =>
@@ -2754,7 +2788,8 @@
               templateNullableMethodCallError.withArguments(
                   name.text, receiverType, isNonNullableByDefault),
               fileOffset,
-              name.text.length);
+              name.text.length,
+              context: getWhyNotPromotedContext(receiver, staticInvocation));
         }
       }
       return createNullAwareExpressionInferenceResult(
@@ -2831,7 +2866,8 @@
             templateNullableMethodCallError.withArguments(
                 callName.text, receiverType, isNonNullableByDefault),
             fileOffset,
-            callName.text.length);
+            callName.text.length,
+            context: getWhyNotPromotedContext(receiver, expression));
       }
     }
     // TODO(johnniwinther): Check that type arguments against the bounds.
@@ -2993,7 +3029,8 @@
             templateNullableMethodCallError.withArguments(
                 methodName.text, receiverType, isNonNullableByDefault),
             fileOffset,
-            methodName.text.length);
+            methodName.text.length,
+            context: getWhyNotPromotedContext(receiver, expression));
       }
     }
 
@@ -4836,3 +4873,63 @@
 
   InferredFunctionBody(this.body, this.futureValueType);
 }
+
+class _WhyNotPromotedVisitor
+    implements
+        NonPromotionReasonVisitor<LocatedMessage, Node, Expression,
+            VariableDeclaration> {
+  final TypeInferrerImpl inferrer;
+
+  final Expression receiver;
+
+  Member propertyReference;
+
+  _WhyNotPromotedVisitor(this.inferrer, this.receiver);
+
+  @override
+  LocatedMessage visitDemoteViaExplicitWrite(
+      DemoteViaExplicitWrite<VariableDeclaration, Expression> reason) {
+    if (inferrer.dataForTesting != null) {
+      inferrer.dataForTesting.flowAnalysisResult
+          .nonPromotionReasonTargets[reason.writeExpression] = reason.shortName;
+    }
+    int offset = reason.writeExpression.fileOffset;
+    return templateVariableCouldBeNullDueToWrite
+        .withArguments(reason.variable.name)
+        .withLocation(inferrer.helper.uri, offset, noLength);
+  }
+
+  @override
+  LocatedMessage visitDemoteViaForEachVariableWrite(
+      DemoteViaForEachVariableWrite<VariableDeclaration, Node> reason) {
+    int offset = (reason.node as TreeNode).fileOffset;
+    return templateVariableCouldBeNullDueToWrite
+        .withArguments(reason.variable.name)
+        .withLocation(inferrer.helper.uri, offset, noLength);
+  }
+
+  @override
+  LocatedMessage visitPropertyNotPromoted(PropertyNotPromoted reason) {
+    Member member;
+    Expression receiver = this.receiver;
+    if (receiver is InstanceGet) {
+      member = receiver.interfaceTarget;
+    } else if (receiver is SuperPropertyGet) {
+      member = receiver.interfaceTarget;
+    } else if (receiver is StaticInvocation) {
+      member = receiver.target;
+    } else if (receiver is PropertyGet) {
+      member = receiver.interfaceTarget;
+    } else {
+      assert(false, 'Unrecognized receiver: ${receiver.runtimeType}');
+    }
+    if (member != null) {
+      propertyReference = member;
+      return templateFieldNotPromoted
+          .withArguments(reason.propertyName)
+          .withLocation(member.fileUri, member.fileOffset, noLength);
+    } else {
+      return null;
+    }
+  }
+}
diff --git a/pkg/front_end/test/lint_test.status b/pkg/front_end/test/lint_test.status
index aaa6e98..2728954 100644
--- a/pkg/front_end/test/lint_test.status
+++ b/pkg/front_end/test/lint_test.status
@@ -20,7 +20,6 @@
 front_end/lib/src/fasta/kernel/body_builder/ImportsTwice: Fail
 front_end/lib/src/fasta/kernel/constant_evaluator/ExplicitType: Pass
 front_end/lib/src/fasta/kernel/expression_generator_helper/ImportsTwice: Fail
-front_end/lib/src/fasta/kernel/inference_visitor/ImportsTwice: Fail
 front_end/lib/src/fasta/kernel/kernel_api/Exports: Fail
 front_end/lib/src/fasta/kernel/kernel_ast_api/Exports: Fail
 front_end/lib/src/fasta/kernel/kernel_builder/Exports: Fail
diff --git a/pkg/front_end/test/spell_checking_list_code.txt b/pkg/front_end/test/spell_checking_list_code.txt
index 7900556..5d9da02 100644
--- a/pkg/front_end/test/spell_checking_list_code.txt
+++ b/pkg/front_end/test/spell_checking_list_code.txt
@@ -390,6 +390,7 @@
 exp
 expando
 expense
+explaining
 exportable
 exportee
 exportees
diff --git a/tools/VERSION b/tools/VERSION
index 5505a1f..b7fdb1d 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -27,5 +27,5 @@
 MAJOR 2
 MINOR 13
 PATCH 0
-PRERELEASE 34
+PRERELEASE 35
 PRERELEASE_PATCH 0
\ No newline at end of file