diff --git a/pkg/front_end/lib/src/fasta/builder/named_type_builder.dart b/pkg/front_end/lib/src/fasta/builder/named_type_builder.dart
index 1833d4f..31a334d 100644
--- a/pkg/front_end/lib/src/fasta/builder/named_type_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/named_type_builder.dart
@@ -21,6 +21,8 @@
         templateExtendingRestricted,
         templateNotAType,
         templateSupertypeIsIllegal,
+        templateSupertypeIsIllegalAliased,
+        templateSupertypeIsNullableAliased,
         templateSupertypeIsTypeVariable,
         templateTypeArgumentMismatch,
         templateTypeArgumentsOnTypeVariable,
@@ -177,7 +179,7 @@
   String get debugName => "NamedTypeBuilder";
 
   StringBuffer printOn(StringBuffer buffer) {
-    buffer.write(name);
+    buffer.write(flattenName(name, charOffset, fileUri));
     if (arguments?.isEmpty ?? true) return buffer;
     buffer.write("<");
     bool first = true;
@@ -201,29 +203,39 @@
         context: context);
   }
 
-  Supertype handleInvalidSupertype(LibraryBuilder library, int charOffset,
-      Uri fileUri, TypeAliasBuilder aliasBuilder) {
+  Supertype handleInvalidSupertype(
+      LibraryBuilder library, int charOffset, Uri fileUri) {
     Template<Message Function(String name)> template =
         declaration.isTypeVariable
             ? templateSupertypeIsTypeVariable
             : templateSupertypeIsIllegal;
-    if (aliasBuilder != null) {
-      library.addProblem(
-          template.withArguments(flattenName(name, charOffset, fileUri)),
-          charOffset,
-          noLength,
-          fileUri,
-          context: [
-            messageTypedefCause.withLocation(
-                aliasBuilder.fileUri, aliasBuilder.charOffset, noLength),
-          ]);
-    } else {
-      library.addProblem(
-          template.withArguments(flattenName(name, charOffset, fileUri)),
-          charOffset,
-          noLength,
-          fileUri);
-    }
+    library.addProblem(template.withArguments(fullNameForErrors), charOffset,
+        noLength, fileUri);
+    return null;
+  }
+
+  Supertype handleInvalidAliasedSupertype(
+      LibraryBuilder library,
+      int charOffset,
+      Uri fileUri,
+      TypeAliasBuilder aliasBuilder,
+      DartType type) {
+    Template<Message Function(String name, DartType type, bool)> template =
+        declaration.isTypeVariable
+            ? templateSupertypeIsTypeVariable
+            : (type != null && type.nullability == Nullability.nullable
+                ? templateSupertypeIsNullableAliased
+                : templateSupertypeIsIllegalAliased);
+    library.addProblem(
+        template.withArguments(
+            fullNameForErrors, type, library.isNonNullableByDefault),
+        charOffset,
+        noLength,
+        fileUri,
+        context: [
+          messageTypedefCause.withLocation(
+              aliasBuilder.fileUri, aliasBuilder.charOffset, noLength),
+        ]);
     return null;
   }
 
@@ -266,7 +278,6 @@
   Supertype buildSupertype(
       LibraryBuilder library, int charOffset, Uri fileUri) {
     TypeDeclarationBuilder declaration = this.declaration;
-    TypeAliasBuilder aliasBuilder; // Non-null if a type alias is used.
     if (declaration is ClassBuilder) {
       if (declaration.isNullClass && !library.mayImplementRestrictedTypes) {
         library.addProblem(
@@ -277,10 +288,10 @@
       }
       return declaration.buildSupertype(library, arguments);
     } else if (declaration is TypeAliasBuilder) {
-      aliasBuilder = declaration;
+      TypeAliasBuilder aliasBuilder = declaration;
       DartType type =
           declaration.buildType(library, library.nonNullableBuilder, arguments);
-      if (type is InterfaceType) {
+      if (type is InterfaceType && type.nullability != Nullability.nullable) {
         return new Supertype(type.classNode, type.typeArguments);
       } else if (type is NullType) {
         // Even though Null is disallowed as a supertype, ClassHierarchyBuilder
@@ -324,9 +335,9 @@
             unaliasedDeclaration.name == "FutureOr");
         return new Supertype((unaliasedDeclaration as ClassBuilder).cls,
             <DartType>[type.typeArgument]);
-      } else {
-        // Do nothing: handleInvalidSuper below will handle the erroneous case.
       }
+      return handleInvalidAliasedSupertype(
+          library, charOffset, fileUri, aliasBuilder, type);
     } else if (declaration is InvalidTypeDeclarationBuilder) {
       library.addProblem(
           declaration.message.messageObject,
@@ -336,22 +347,23 @@
           severity: Severity.error);
       return null;
     }
-    return handleInvalidSupertype(library, charOffset, fileUri, aliasBuilder);
+    return handleInvalidSupertype(library, charOffset, fileUri);
   }
 
   Supertype buildMixedInType(
       LibraryBuilder library, int charOffset, Uri fileUri) {
     TypeDeclarationBuilder declaration = this.declaration;
-    TypeAliasBuilder aliasBuilder; // Non-null if a type alias is used.
     if (declaration is ClassBuilder) {
       return declaration.buildMixedInType(library, arguments);
     } else if (declaration is TypeAliasBuilder) {
-      aliasBuilder = declaration;
+      TypeAliasBuilder aliasBuilder = declaration;
       DartType type =
           declaration.buildType(library, library.nonNullableBuilder, arguments);
-      if (type is InterfaceType) {
+      if (type is InterfaceType && type.nullability != Nullability.nullable) {
         return new Supertype(type.classNode, type.typeArguments);
       }
+      return handleInvalidAliasedSupertype(
+          library, charOffset, fileUri, aliasBuilder, type);
     } else if (declaration is InvalidTypeDeclarationBuilder) {
       library.addProblem(
           declaration.message.messageObject,
@@ -361,7 +373,7 @@
           severity: Severity.error);
       return null;
     }
-    return handleInvalidSupertype(library, charOffset, fileUri, aliasBuilder);
+    return handleInvalidSupertype(library, charOffset, fileUri);
   }
 
   TypeBuilder subst(Map<TypeVariableBuilder, TypeBuilder> substitution) {
diff --git a/pkg/front_end/lib/src/fasta/fasta_codes_cfe_generated.dart b/pkg/front_end/lib/src/fasta/fasta_codes_cfe_generated.dart
index 21f427c..4e0e710 100644
--- a/pkg/front_end/lib/src/fasta/fasta_codes_cfe_generated.dart
+++ b/pkg/front_end/lib/src/fasta/fasta_codes_cfe_generated.dart
@@ -4631,6 +4631,78 @@
 // DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
 const Template<
         Message Function(
+            String name, DartType _type, bool isNonNullableByDefault)>
+    templateSupertypeIsIllegalAliased = const Template<
+            Message Function(
+                String name, DartType _type, bool isNonNullableByDefault)>(
+        messageTemplate:
+            r"""The type '#name' which is an alias of '#type' can't be used as supertype.""",
+        withArguments: _withArgumentsSupertypeIsIllegalAliased);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<
+        Message Function(
+            String name, DartType _type, bool isNonNullableByDefault)>
+    codeSupertypeIsIllegalAliased = const Code<
+            Message Function(
+                String name, DartType _type, bool isNonNullableByDefault)>(
+        "SupertypeIsIllegalAliased",
+        analyzerCodes: <String>["EXTENDS_NON_CLASS"]);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsSupertypeIsIllegalAliased(
+    String name, DartType _type, bool isNonNullableByDefault) {
+  if (name.isEmpty) throw 'No name provided';
+  name = demangleMixinApplicationName(name);
+  TypeLabeler labeler = new TypeLabeler(isNonNullableByDefault);
+  List<Object> typeParts = labeler.labelType(_type);
+  String type = typeParts.join();
+  return new Message(codeSupertypeIsIllegalAliased,
+      message:
+          """The type '${name}' which is an alias of '${type}' can't be used as supertype.""" +
+              labeler.originMessages,
+      arguments: {'name': name, 'type': _type});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+        Message Function(
+            String name, DartType _type, bool isNonNullableByDefault)>
+    templateSupertypeIsNullableAliased = const Template<
+            Message Function(
+                String name, DartType _type, bool isNonNullableByDefault)>(
+        messageTemplate:
+            r"""The type '#name' which is an alias of '#type' can't be used as supertype because it is nullable.""",
+        withArguments: _withArgumentsSupertypeIsNullableAliased);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Code<
+        Message Function(
+            String name, DartType _type, bool isNonNullableByDefault)>
+    codeSupertypeIsNullableAliased = const Code<
+            Message Function(
+                String name, DartType _type, bool isNonNullableByDefault)>(
+        "SupertypeIsNullableAliased",
+        analyzerCodes: <String>["EXTENDS_NON_CLASS"]);
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+Message _withArgumentsSupertypeIsNullableAliased(
+    String name, DartType _type, bool isNonNullableByDefault) {
+  if (name.isEmpty) throw 'No name provided';
+  name = demangleMixinApplicationName(name);
+  TypeLabeler labeler = new TypeLabeler(isNonNullableByDefault);
+  List<Object> typeParts = labeler.labelType(_type);
+  String type = typeParts.join();
+  return new Message(codeSupertypeIsNullableAliased,
+      message:
+          """The type '${name}' which is an alias of '${type}' can't be used as supertype because it is nullable.""" +
+              labeler.originMessages,
+      arguments: {'name': name, 'type': _type});
+}
+
+// DO NOT EDIT. THIS FILE IS GENERATED. SEE TOP OF FILE.
+const Template<
+        Message Function(
             DartType _type, DartType _type2, bool isNonNullableByDefault)>
     templateSwitchExpressionNotAssignable = const Template<
             Message Function(
diff --git a/pkg/front_end/lib/src/fasta/kernel/type_labeler.dart b/pkg/front_end/lib/src/fasta/kernel/type_labeler.dart
index f7d816c..e097eca 100644
--- a/pkg/front_end/lib/src/fasta/kernel/type_labeler.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/type_labeler.dart
@@ -112,8 +112,8 @@
     result.add(nameForEntity(
         typedefNode,
         typedefNode.name,
-        typedefNode.enclosingLibrary.importUri,
-        typedefNode.enclosingLibrary.fileUri));
+        typedefNode?.enclosingLibrary?.importUri ?? unknownUri,
+        typedefNode?.enclosingLibrary?.fileUri ?? unknownUri));
     if (node.typeArguments.isNotEmpty) {
       result.add("<");
       bool first = true;
@@ -226,8 +226,10 @@
     result.add(nameForEntity(
         classNode,
         classNode.name,
-        classNode.enclosingLibrary.importUri,
-        classNode.enclosingLibrary.fileUri));
+        // TODO(johnniwinther): Ensure enclosing libraries on classes earlier
+        // in the compiler to ensure types in error messages have context.
+        classNode?.enclosingLibrary?.importUri ?? unknownUri,
+        classNode?.enclosingLibrary?.fileUri ?? unknownUri));
     if (node.typeArguments.isNotEmpty) {
       result.add("<");
       bool first = true;
@@ -252,8 +254,8 @@
     result.add(nameForEntity(
         node.extension,
         node.extension.name,
-        node.extension.enclosingLibrary.importUri,
-        node.extension.enclosingLibrary.fileUri));
+        node.extension?.enclosingLibrary?.importUri ?? unknownUri,
+        node.extension?.enclosingLibrary?.fileUri ?? unknownUri));
     if (node.typeArguments.isNotEmpty) {
       result.add("<");
       bool first = true;
diff --git a/pkg/front_end/messages.status b/pkg/front_end/messages.status
index d25dfc3..cebc0ac 100644
--- a/pkg/front_end/messages.status
+++ b/pkg/front_end/messages.status
@@ -745,6 +745,8 @@
 SupertypeIsFunction/analyzerCode: Fail
 SupertypeIsFunction/example: Fail
 SupertypeIsIllegal/example: Fail
+SupertypeIsIllegalAliased/example: Fail
+SupertypeIsNullableAliased/example: Fail
 SupertypeIsTypeVariable/example: Fail
 SwitchCaseFallThrough/example: Fail
 SwitchExpressionNotSubtype/analyzerCode: Fail
diff --git a/pkg/front_end/messages.yaml b/pkg/front_end/messages.yaml
index c5be3f5..9525c92 100644
--- a/pkg/front_end/messages.yaml
+++ b/pkg/front_end/messages.yaml
@@ -2952,6 +2952,14 @@
   template: "The type '#name' can't be used as supertype."
   analyzerCode: EXTENDS_NON_CLASS
 
+SupertypeIsIllegalAliased:
+  template: "The type '#name' which is an alias of '#type' can't be used as supertype."
+  analyzerCode: EXTENDS_NON_CLASS
+
+SupertypeIsNullableAliased:
+  template: "The type '#name' which is an alias of '#type' can't be used as supertype because it is nullable."
+  analyzerCode: EXTENDS_NON_CLASS
+
 SupertypeIsTypeVariable:
   template: "The type variable '#name' can't be used as supertype."
   analyzerCode: EXTENDS_NON_CLASS
diff --git a/pkg/front_end/test/spell_checking_list_tests.txt b/pkg/front_end/test/spell_checking_list_tests.txt
index 8050222..17ee5f0 100644
--- a/pkg/front_end/test/spell_checking_list_tests.txt
+++ b/pkg/front_end/test/spell_checking_list_tests.txt
@@ -180,6 +180,8 @@
 cursor
 cuts
 cx
+d1a
+d1b
 dacoharkes
 dadd
 daemon
@@ -523,6 +525,8 @@
 mx
 mxn
 mysdk
+n1a
+n1b
 naively
 naturally
 negatable
diff --git a/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart
new file mode 100644
index 0000000..366c73b7
--- /dev/null
+++ b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart
@@ -0,0 +1,17 @@
+// 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.
+
+typedef F = T Function<T, S>(T, S);
+
+class Class<A> {
+  method() {
+    const G = F;
+    print(F);
+    print(G);
+  }
+}
+
+main() {
+  new Class<int>().method();
+}
diff --git a/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.textual_outline.expect b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.textual_outline.expect
new file mode 100644
index 0000000..244f23d
--- /dev/null
+++ b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.textual_outline.expect
@@ -0,0 +1,7 @@
+typedef F = T Function<T, S>(T, S);
+
+class Class<A> {
+  method() {}
+}
+
+main() {}
diff --git a/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.textual_outline_modelled.expect b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.textual_outline_modelled.expect
new file mode 100644
index 0000000..bb25297
--- /dev/null
+++ b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.textual_outline_modelled.expect
@@ -0,0 +1,6 @@
+class Class<A> {
+  method() {}
+}
+
+main() {}
+typedef F = T Function<T, S>(T, S);
diff --git a/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.weak.expect b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.weak.expect
new file mode 100644
index 0000000..542c883
--- /dev/null
+++ b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.weak.expect
@@ -0,0 +1,21 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+typedef F = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%) → T%;
+class Class<A extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::Class<self::Class::A%>
+    : super core::Object::•()
+    ;
+  method method() → dynamic {
+    core::print(#C1);
+    core::print(#C1);
+  }
+}
+static method main() → dynamic {
+  new self::Class::•<core::int>().{self::Class::method}();
+}
+
+constants  {
+  #C1 = TypeLiteralConstant(<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T*, S*) →* T*)
+}
diff --git a/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.weak.outline.expect b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.weak.outline.expect
new file mode 100644
index 0000000..6a9b7fb
--- /dev/null
+++ b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.weak.outline.expect
@@ -0,0 +1,13 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+typedef F = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%) → T%;
+class Class<A extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::Class<self::Class::A%>
+    ;
+  method method() → dynamic
+    ;
+}
+static method main() → dynamic
+  ;
diff --git a/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.weak.transformed.expect b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.weak.transformed.expect
new file mode 100644
index 0000000..542c883
--- /dev/null
+++ b/pkg/front_end/testcases/general/generic_typedef_in_generic_class.dart.weak.transformed.expect
@@ -0,0 +1,21 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+typedef F = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%) → T%;
+class Class<A extends core::Object? = dynamic> extends core::Object {
+  synthetic constructor •() → self::Class<self::Class::A%>
+    : super core::Object::•()
+    ;
+  method method() → dynamic {
+    core::print(#C1);
+    core::print(#C1);
+  }
+}
+static method main() → dynamic {
+  new self::Class::•<core::int>().{self::Class::method}();
+}
+
+constants  {
+  #C1 = TypeLiteralConstant(<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T*, S*) →* T*)
+}
diff --git a/pkg/front_end/testcases/general/qualified.dart.weak.expect b/pkg/front_end/testcases/general/qualified.dart.weak.expect
index a51969d..b829051 100644
--- a/pkg/front_end/testcases/general/qualified.dart.weak.expect
+++ b/pkg/front_end/testcases/general/qualified.dart.weak.expect
@@ -17,7 +17,7 @@
 //   lib.Missing method() {}
 //   ^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/qualified.dart:18:7: Error: The type 'lib.VoidFunction' can't be used as supertype.
+// pkg/front_end/testcases/general/qualified.dart:18:7: Error: The type 'lib.VoidFunction' which is an alias of 'void Function()' can't be used as supertype.
 // class IllegalSupertype extends lib.VoidFunction {}
 //       ^
 // pkg/front_end/testcases/general/qualified_lib.dart:27:9: Context: The issue arises via this type alias.
diff --git a/pkg/front_end/testcases/general/qualified.dart.weak.outline.expect b/pkg/front_end/testcases/general/qualified.dart.weak.outline.expect
index fcf8ecc..2102d04 100644
--- a/pkg/front_end/testcases/general/qualified.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/general/qualified.dart.weak.outline.expect
@@ -17,7 +17,7 @@
 //   lib.Missing method() {}
 //   ^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/qualified.dart:18:7: Error: The type 'lib.VoidFunction' can't be used as supertype.
+// pkg/front_end/testcases/general/qualified.dart:18:7: Error: The type 'lib.VoidFunction' which is an alias of 'void Function()' can't be used as supertype.
 // class IllegalSupertype extends lib.VoidFunction {}
 //       ^
 // pkg/front_end/testcases/general/qualified_lib.dart:27:9: Context: The issue arises via this type alias.
diff --git a/pkg/front_end/testcases/general/qualified.dart.weak.transformed.expect b/pkg/front_end/testcases/general/qualified.dart.weak.transformed.expect
index 25de173..003ca00 100644
--- a/pkg/front_end/testcases/general/qualified.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general/qualified.dart.weak.transformed.expect
@@ -17,7 +17,7 @@
 //   lib.Missing method() {}
 //   ^^^^^^^^^^^
 //
-// pkg/front_end/testcases/general/qualified.dart:18:7: Error: The type 'lib.VoidFunction' can't be used as supertype.
+// pkg/front_end/testcases/general/qualified.dart:18:7: Error: The type 'lib.VoidFunction' which is an alias of 'void Function()' can't be used as supertype.
 // class IllegalSupertype extends lib.VoidFunction {}
 //       ^
 // pkg/front_end/testcases/general/qualified_lib.dart:27:9: Context: The issue arises via this type alias.
diff --git a/pkg/front_end/testcases/generic_metadata/from_dill/main.dart b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart
new file mode 100644
index 0000000..6ac6d2c
--- /dev/null
+++ b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart
@@ -0,0 +1,26 @@
+// 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.
+
+import 'main_lib.dart';
+
+main() {
+  C1 c1 = C1();
+  C1 c2 = C1<T Function<T>(T)>();
+
+  C2 c3 = C2();
+  C2 c4 = C2<void Function<int>()>();
+
+  C3 c5 = C3();
+  C3 c6 = C3<T Function<T>()>();
+
+  C4 c7 = C4();
+  C4 c8 = C4<void Function<T>(T)>();
+
+  C5 c9 = C5();
+  C5 c10 = C5<T Function<T extends S Function<S>(S)>(T)>();
+
+  C6 c11 = C6();
+  C6 c12 = C6<
+      T Function<T, S>(T, S, V Function<V extends S, U>(T, U, V, Map<S, U>))>();
+}
diff --git a/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.strong.expect b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.strong.expect
new file mode 100644
index 0000000..92b41bb
--- /dev/null
+++ b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.strong.expect
@@ -0,0 +1,81 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "main_lib.dart" as mai;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///main_lib.dart";
+
+static method main() → dynamic {
+  mai::C1<<T extends core::Object? = dynamic>(T%) → T%> c1 = new mai::C1::•<<T extends core::Object? = dynamic>(T%) → T%>();
+  mai::C1<<T extends core::Object? = dynamic>(T%) → T%> c2 = new mai::C1::•<<T extends core::Object? = dynamic>(T%) → T%>();
+  mai::C2<<T extends core::Object? = dynamic>() → void> c3 = new mai::C2::•<<T extends core::Object? = dynamic>() → void>();
+  mai::C2<<T extends core::Object? = dynamic>() → void> c4 = new mai::C2::•<<int extends core::Object? = dynamic>() → void>();
+  mai::C3<<T extends core::Object? = dynamic>() → T%> c5 = new mai::C3::•<<T extends core::Object? = dynamic>() → T%>();
+  mai::C3<<T extends core::Object? = dynamic>() → T%> c6 = new mai::C3::•<<T extends core::Object? = dynamic>() → T%>();
+  mai::C4<<T extends core::Object? = dynamic>(T%) → void> c7 = new mai::C4::•<<T extends core::Object? = dynamic>(T%) → void>();
+  mai::C4<<T extends core::Object? = dynamic>(T%) → void> c8 = new mai::C4::•<<T extends core::Object? = dynamic>(T%) → void>();
+  mai::C5<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> c9 = new mai::C5::•<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T>();
+  mai::C5<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> c10 = new mai::C5::•<<T extends <S extends core::Object? = dynamic>(S%) → S% = <S extends core::Object? = dynamic>(S%) → S%>(T) → T>();
+  mai::C6<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> c11 = new mai::C6::•<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%>();
+  mai::C6<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> c12 = new mai::C6::•<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = S%, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%>();
+}
+
+library /*isNonNullableByDefault*/;
+import self as mai;
+import "dart:core" as core;
+
+typedef exp1 = <T extends core::Object? = dynamic>(T%) → T%;
+typedef exp2 = <T extends core::Object? = dynamic>() → void;
+typedef exp3 = <T extends core::Object? = dynamic>() → T%;
+typedef exp4 = <T extends core::Object? = dynamic>(T%) → void;
+typedef exp5 = <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T;
+typedef exp6 = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%;
+class C1<X extends <T extends core::Object? = dynamic>(T%) → T% = <T extends core::Object? = dynamic>(T%) → T%> extends core::Object {
+  constructor •() → mai::C1<mai::C1::X>
+    : super core::Object::•() {
+    mai::expect(#C1, mai::C1::X);
+  }
+}
+class C2<X extends <T extends core::Object? = dynamic>() → void = <T extends core::Object? = dynamic>() → void> extends core::Object {
+  constructor •() → mai::C2<mai::C2::X>
+    : super core::Object::•() {
+    mai::expect(#C2, mai::C2::X);
+  }
+}
+class C3<X extends <T extends core::Object? = dynamic>() → T% = <T extends core::Object? = dynamic>() → T%> extends core::Object {
+  constructor •() → mai::C3<mai::C3::X>
+    : super core::Object::•() {
+    mai::expect(#C3, mai::C3::X);
+  }
+}
+class C4<X extends <T extends core::Object? = dynamic>(T%) → void = <T extends core::Object? = dynamic>(T%) → void> extends core::Object {
+  constructor •() → mai::C4<mai::C4::X>
+    : super core::Object::•() {
+    mai::expect(#C4, mai::C4::X);
+  }
+}
+class C5<X extends <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T = <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> extends core::Object {
+  constructor •() → mai::C5<mai::C5::X>
+    : super core::Object::•() {
+    mai::expect(#C5, mai::C5::X);
+  }
+}
+class C6<X extends <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T% = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> extends core::Object {
+  constructor •() → mai::C6<mai::C6::X>
+    : super core::Object::•() {
+    mai::expect(#C6, mai::C6::X);
+  }
+}
+static method expect(dynamic expected, dynamic actual) → dynamic {
+  if(!expected.{core::Object::==}(actual))
+    throw "Expected ${expected}, actual ${actual}";
+}
+
+constants  {
+  #C1 = TypeLiteralConstant(<T extends core::Object? = dynamic>(T%) → T%)
+  #C2 = TypeLiteralConstant(<T extends core::Object? = dynamic>() → void)
+  #C3 = TypeLiteralConstant(<T extends core::Object? = dynamic>() → T%)
+  #C4 = TypeLiteralConstant(<T extends core::Object? = dynamic>(T%) → void)
+  #C5 = TypeLiteralConstant(<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T)
+  #C6 = TypeLiteralConstant(<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%)
+}
diff --git a/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.strong.transformed.expect b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.strong.transformed.expect
new file mode 100644
index 0000000..92b41bb
--- /dev/null
+++ b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.strong.transformed.expect
@@ -0,0 +1,81 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "main_lib.dart" as mai;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///main_lib.dart";
+
+static method main() → dynamic {
+  mai::C1<<T extends core::Object? = dynamic>(T%) → T%> c1 = new mai::C1::•<<T extends core::Object? = dynamic>(T%) → T%>();
+  mai::C1<<T extends core::Object? = dynamic>(T%) → T%> c2 = new mai::C1::•<<T extends core::Object? = dynamic>(T%) → T%>();
+  mai::C2<<T extends core::Object? = dynamic>() → void> c3 = new mai::C2::•<<T extends core::Object? = dynamic>() → void>();
+  mai::C2<<T extends core::Object? = dynamic>() → void> c4 = new mai::C2::•<<int extends core::Object? = dynamic>() → void>();
+  mai::C3<<T extends core::Object? = dynamic>() → T%> c5 = new mai::C3::•<<T extends core::Object? = dynamic>() → T%>();
+  mai::C3<<T extends core::Object? = dynamic>() → T%> c6 = new mai::C3::•<<T extends core::Object? = dynamic>() → T%>();
+  mai::C4<<T extends core::Object? = dynamic>(T%) → void> c7 = new mai::C4::•<<T extends core::Object? = dynamic>(T%) → void>();
+  mai::C4<<T extends core::Object? = dynamic>(T%) → void> c8 = new mai::C4::•<<T extends core::Object? = dynamic>(T%) → void>();
+  mai::C5<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> c9 = new mai::C5::•<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T>();
+  mai::C5<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> c10 = new mai::C5::•<<T extends <S extends core::Object? = dynamic>(S%) → S% = <S extends core::Object? = dynamic>(S%) → S%>(T) → T>();
+  mai::C6<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> c11 = new mai::C6::•<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%>();
+  mai::C6<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> c12 = new mai::C6::•<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = S%, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%>();
+}
+
+library /*isNonNullableByDefault*/;
+import self as mai;
+import "dart:core" as core;
+
+typedef exp1 = <T extends core::Object? = dynamic>(T%) → T%;
+typedef exp2 = <T extends core::Object? = dynamic>() → void;
+typedef exp3 = <T extends core::Object? = dynamic>() → T%;
+typedef exp4 = <T extends core::Object? = dynamic>(T%) → void;
+typedef exp5 = <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T;
+typedef exp6 = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%;
+class C1<X extends <T extends core::Object? = dynamic>(T%) → T% = <T extends core::Object? = dynamic>(T%) → T%> extends core::Object {
+  constructor •() → mai::C1<mai::C1::X>
+    : super core::Object::•() {
+    mai::expect(#C1, mai::C1::X);
+  }
+}
+class C2<X extends <T extends core::Object? = dynamic>() → void = <T extends core::Object? = dynamic>() → void> extends core::Object {
+  constructor •() → mai::C2<mai::C2::X>
+    : super core::Object::•() {
+    mai::expect(#C2, mai::C2::X);
+  }
+}
+class C3<X extends <T extends core::Object? = dynamic>() → T% = <T extends core::Object? = dynamic>() → T%> extends core::Object {
+  constructor •() → mai::C3<mai::C3::X>
+    : super core::Object::•() {
+    mai::expect(#C3, mai::C3::X);
+  }
+}
+class C4<X extends <T extends core::Object? = dynamic>(T%) → void = <T extends core::Object? = dynamic>(T%) → void> extends core::Object {
+  constructor •() → mai::C4<mai::C4::X>
+    : super core::Object::•() {
+    mai::expect(#C4, mai::C4::X);
+  }
+}
+class C5<X extends <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T = <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> extends core::Object {
+  constructor •() → mai::C5<mai::C5::X>
+    : super core::Object::•() {
+    mai::expect(#C5, mai::C5::X);
+  }
+}
+class C6<X extends <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T% = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> extends core::Object {
+  constructor •() → mai::C6<mai::C6::X>
+    : super core::Object::•() {
+    mai::expect(#C6, mai::C6::X);
+  }
+}
+static method expect(dynamic expected, dynamic actual) → dynamic {
+  if(!expected.{core::Object::==}(actual))
+    throw "Expected ${expected}, actual ${actual}";
+}
+
+constants  {
+  #C1 = TypeLiteralConstant(<T extends core::Object? = dynamic>(T%) → T%)
+  #C2 = TypeLiteralConstant(<T extends core::Object? = dynamic>() → void)
+  #C3 = TypeLiteralConstant(<T extends core::Object? = dynamic>() → T%)
+  #C4 = TypeLiteralConstant(<T extends core::Object? = dynamic>(T%) → void)
+  #C5 = TypeLiteralConstant(<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T)
+  #C6 = TypeLiteralConstant(<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%)
+}
diff --git a/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.textual_outline.expect b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.textual_outline.expect
new file mode 100644
index 0000000..82be6bb
--- /dev/null
+++ b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.textual_outline.expect
@@ -0,0 +1,3 @@
+import 'main_lib.dart';
+
+main() {}
diff --git a/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.textual_outline_modelled.expect b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.textual_outline_modelled.expect
new file mode 100644
index 0000000..82be6bb
--- /dev/null
+++ b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.textual_outline_modelled.expect
@@ -0,0 +1,3 @@
+import 'main_lib.dart';
+
+main() {}
diff --git a/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.weak.expect b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.weak.expect
new file mode 100644
index 0000000..e1e7067
--- /dev/null
+++ b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.weak.expect
@@ -0,0 +1,81 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "main_lib.dart" as mai;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///main_lib.dart";
+
+static method main() → dynamic {
+  mai::C1<<T extends core::Object? = dynamic>(T%) → T%> c1 = new mai::C1::•<<T extends core::Object? = dynamic>(T%) → T%>();
+  mai::C1<<T extends core::Object? = dynamic>(T%) → T%> c2 = new mai::C1::•<<T extends core::Object? = dynamic>(T%) → T%>();
+  mai::C2<<T extends core::Object? = dynamic>() → void> c3 = new mai::C2::•<<T extends core::Object? = dynamic>() → void>();
+  mai::C2<<T extends core::Object? = dynamic>() → void> c4 = new mai::C2::•<<int extends core::Object? = dynamic>() → void>();
+  mai::C3<<T extends core::Object? = dynamic>() → T%> c5 = new mai::C3::•<<T extends core::Object? = dynamic>() → T%>();
+  mai::C3<<T extends core::Object? = dynamic>() → T%> c6 = new mai::C3::•<<T extends core::Object? = dynamic>() → T%>();
+  mai::C4<<T extends core::Object? = dynamic>(T%) → void> c7 = new mai::C4::•<<T extends core::Object? = dynamic>(T%) → void>();
+  mai::C4<<T extends core::Object? = dynamic>(T%) → void> c8 = new mai::C4::•<<T extends core::Object? = dynamic>(T%) → void>();
+  mai::C5<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> c9 = new mai::C5::•<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T>();
+  mai::C5<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> c10 = new mai::C5::•<<T extends <S extends core::Object? = dynamic>(S%) → S% = <S extends core::Object? = dynamic>(S%) → S%>(T) → T>();
+  mai::C6<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> c11 = new mai::C6::•<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%>();
+  mai::C6<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> c12 = new mai::C6::•<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = S%, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%>();
+}
+
+library /*isNonNullableByDefault*/;
+import self as mai;
+import "dart:core" as core;
+
+typedef exp1 = <T extends core::Object? = dynamic>(T%) → T%;
+typedef exp2 = <T extends core::Object? = dynamic>() → void;
+typedef exp3 = <T extends core::Object? = dynamic>() → T%;
+typedef exp4 = <T extends core::Object? = dynamic>(T%) → void;
+typedef exp5 = <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T;
+typedef exp6 = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%;
+class C1<X extends <T extends core::Object? = dynamic>(T%) → T% = <T extends core::Object? = dynamic>(T%) → T%> extends core::Object {
+  constructor •() → mai::C1<mai::C1::X>
+    : super core::Object::•() {
+    mai::expect(#C1, mai::C1::X);
+  }
+}
+class C2<X extends <T extends core::Object? = dynamic>() → void = <T extends core::Object? = dynamic>() → void> extends core::Object {
+  constructor •() → mai::C2<mai::C2::X>
+    : super core::Object::•() {
+    mai::expect(#C2, mai::C2::X);
+  }
+}
+class C3<X extends <T extends core::Object? = dynamic>() → T% = <T extends core::Object? = dynamic>() → T%> extends core::Object {
+  constructor •() → mai::C3<mai::C3::X>
+    : super core::Object::•() {
+    mai::expect(#C3, mai::C3::X);
+  }
+}
+class C4<X extends <T extends core::Object? = dynamic>(T%) → void = <T extends core::Object? = dynamic>(T%) → void> extends core::Object {
+  constructor •() → mai::C4<mai::C4::X>
+    : super core::Object::•() {
+    mai::expect(#C4, mai::C4::X);
+  }
+}
+class C5<X extends <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T = <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> extends core::Object {
+  constructor •() → mai::C5<mai::C5::X>
+    : super core::Object::•() {
+    mai::expect(#C5, mai::C5::X);
+  }
+}
+class C6<X extends <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T% = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> extends core::Object {
+  constructor •() → mai::C6<mai::C6::X>
+    : super core::Object::•() {
+    mai::expect(#C6, mai::C6::X);
+  }
+}
+static method expect(dynamic expected, dynamic actual) → dynamic {
+  if(!expected.{core::Object::==}(actual))
+    throw "Expected ${expected}, actual ${actual}";
+}
+
+constants  {
+  #C1 = TypeLiteralConstant(<T extends core::Object? = dynamic>(T*) →* T*)
+  #C2 = TypeLiteralConstant(<T extends core::Object? = dynamic>() →* void)
+  #C3 = TypeLiteralConstant(<T extends core::Object? = dynamic>() →* T*)
+  #C4 = TypeLiteralConstant(<T extends core::Object? = dynamic>(T*) →* void)
+  #C5 = TypeLiteralConstant(<T extends <S extends core::Object? = dynamic>(S*) →* S* = <S extends core::Object? = dynamic>(S*) →* S*>(T*) →* T*)
+  #C6 = TypeLiteralConstant(<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T*, S*, <V extends S* = S*, U extends core::Object? = dynamic>(T*, U*, V*, core::Map<S*, U*>*) →* V*) →* T*)
+}
diff --git a/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.weak.outline.expect b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.weak.outline.expect
new file mode 100644
index 0000000..b9ccc27
--- /dev/null
+++ b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.weak.outline.expect
@@ -0,0 +1,44 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+
+import "org-dartlang-testcase:///main_lib.dart";
+
+static method main() → dynamic
+  ;
+
+library /*isNonNullableByDefault*/;
+import self as self2;
+import "dart:core" as core;
+
+typedef exp1 = <T extends core::Object? = dynamic>(T%) → T%;
+typedef exp2 = <T extends core::Object? = dynamic>() → void;
+typedef exp3 = <T extends core::Object? = dynamic>() → T%;
+typedef exp4 = <T extends core::Object? = dynamic>(T%) → void;
+typedef exp5 = <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T;
+typedef exp6 = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%;
+class C1<X extends <T extends core::Object? = dynamic>(T%) → T% = <T extends core::Object? = dynamic>(T%) → T%> extends core::Object {
+  constructor •() → self2::C1<self2::C1::X>
+    ;
+}
+class C2<X extends <T extends core::Object? = dynamic>() → void = <T extends core::Object? = dynamic>() → void> extends core::Object {
+  constructor •() → self2::C2<self2::C2::X>
+    ;
+}
+class C3<X extends <T extends core::Object? = dynamic>() → T% = <T extends core::Object? = dynamic>() → T%> extends core::Object {
+  constructor •() → self2::C3<self2::C3::X>
+    ;
+}
+class C4<X extends <T extends core::Object? = dynamic>(T%) → void = <T extends core::Object? = dynamic>(T%) → void> extends core::Object {
+  constructor •() → self2::C4<self2::C4::X>
+    ;
+}
+class C5<X extends <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T = <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> extends core::Object {
+  constructor •() → self2::C5<self2::C5::X>
+    ;
+}
+class C6<X extends <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T% = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> extends core::Object {
+  constructor •() → self2::C6<self2::C6::X>
+    ;
+}
+static method expect(dynamic expected, dynamic actual) → dynamic
+  ;
diff --git a/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.weak.transformed.expect b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.weak.transformed.expect
new file mode 100644
index 0000000..e1e7067
--- /dev/null
+++ b/pkg/front_end/testcases/generic_metadata/from_dill/main.dart.weak.transformed.expect
@@ -0,0 +1,81 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "main_lib.dart" as mai;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///main_lib.dart";
+
+static method main() → dynamic {
+  mai::C1<<T extends core::Object? = dynamic>(T%) → T%> c1 = new mai::C1::•<<T extends core::Object? = dynamic>(T%) → T%>();
+  mai::C1<<T extends core::Object? = dynamic>(T%) → T%> c2 = new mai::C1::•<<T extends core::Object? = dynamic>(T%) → T%>();
+  mai::C2<<T extends core::Object? = dynamic>() → void> c3 = new mai::C2::•<<T extends core::Object? = dynamic>() → void>();
+  mai::C2<<T extends core::Object? = dynamic>() → void> c4 = new mai::C2::•<<int extends core::Object? = dynamic>() → void>();
+  mai::C3<<T extends core::Object? = dynamic>() → T%> c5 = new mai::C3::•<<T extends core::Object? = dynamic>() → T%>();
+  mai::C3<<T extends core::Object? = dynamic>() → T%> c6 = new mai::C3::•<<T extends core::Object? = dynamic>() → T%>();
+  mai::C4<<T extends core::Object? = dynamic>(T%) → void> c7 = new mai::C4::•<<T extends core::Object? = dynamic>(T%) → void>();
+  mai::C4<<T extends core::Object? = dynamic>(T%) → void> c8 = new mai::C4::•<<T extends core::Object? = dynamic>(T%) → void>();
+  mai::C5<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> c9 = new mai::C5::•<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T>();
+  mai::C5<<T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> c10 = new mai::C5::•<<T extends <S extends core::Object? = dynamic>(S%) → S% = <S extends core::Object? = dynamic>(S%) → S%>(T) → T>();
+  mai::C6<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> c11 = new mai::C6::•<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%>();
+  mai::C6<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> c12 = new mai::C6::•<<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = S%, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%>();
+}
+
+library /*isNonNullableByDefault*/;
+import self as mai;
+import "dart:core" as core;
+
+typedef exp1 = <T extends core::Object? = dynamic>(T%) → T%;
+typedef exp2 = <T extends core::Object? = dynamic>() → void;
+typedef exp3 = <T extends core::Object? = dynamic>() → T%;
+typedef exp4 = <T extends core::Object? = dynamic>(T%) → void;
+typedef exp5 = <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T;
+typedef exp6 = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%;
+class C1<X extends <T extends core::Object? = dynamic>(T%) → T% = <T extends core::Object? = dynamic>(T%) → T%> extends core::Object {
+  constructor •() → mai::C1<mai::C1::X>
+    : super core::Object::•() {
+    mai::expect(#C1, mai::C1::X);
+  }
+}
+class C2<X extends <T extends core::Object? = dynamic>() → void = <T extends core::Object? = dynamic>() → void> extends core::Object {
+  constructor •() → mai::C2<mai::C2::X>
+    : super core::Object::•() {
+    mai::expect(#C2, mai::C2::X);
+  }
+}
+class C3<X extends <T extends core::Object? = dynamic>() → T% = <T extends core::Object? = dynamic>() → T%> extends core::Object {
+  constructor •() → mai::C3<mai::C3::X>
+    : super core::Object::•() {
+    mai::expect(#C3, mai::C3::X);
+  }
+}
+class C4<X extends <T extends core::Object? = dynamic>(T%) → void = <T extends core::Object? = dynamic>(T%) → void> extends core::Object {
+  constructor •() → mai::C4<mai::C4::X>
+    : super core::Object::•() {
+    mai::expect(#C4, mai::C4::X);
+  }
+}
+class C5<X extends <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T = <T extends <S extends core::Object? = dynamic>(S%) → S% = dynamic>(T) → T> extends core::Object {
+  constructor •() → mai::C5<mai::C5::X>
+    : super core::Object::•() {
+    mai::expect(#C5, mai::C5::X);
+  }
+}
+class C6<X extends <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T% = <T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T%, S%, <V extends S% = dynamic, U extends core::Object? = dynamic>(T%, U%, V%, core::Map<S%, U%>) → V%) → T%> extends core::Object {
+  constructor •() → mai::C6<mai::C6::X>
+    : super core::Object::•() {
+    mai::expect(#C6, mai::C6::X);
+  }
+}
+static method expect(dynamic expected, dynamic actual) → dynamic {
+  if(!expected.{core::Object::==}(actual))
+    throw "Expected ${expected}, actual ${actual}";
+}
+
+constants  {
+  #C1 = TypeLiteralConstant(<T extends core::Object? = dynamic>(T*) →* T*)
+  #C2 = TypeLiteralConstant(<T extends core::Object? = dynamic>() →* void)
+  #C3 = TypeLiteralConstant(<T extends core::Object? = dynamic>() →* T*)
+  #C4 = TypeLiteralConstant(<T extends core::Object? = dynamic>(T*) →* void)
+  #C5 = TypeLiteralConstant(<T extends <S extends core::Object? = dynamic>(S*) →* S* = <S extends core::Object? = dynamic>(S*) →* S*>(T*) →* T*)
+  #C6 = TypeLiteralConstant(<T extends core::Object? = dynamic, S extends core::Object? = dynamic>(T*, S*, <V extends S* = S*, U extends core::Object? = dynamic>(T*, U*, V*, core::Map<S*, U*>*) →* V*) →* T*)
+}
diff --git a/pkg/front_end/testcases/generic_metadata/from_dill/main_lib.dart b/pkg/front_end/testcases/generic_metadata/from_dill/main_lib.dart
new file mode 100644
index 0000000..5a1661c
--- /dev/null
+++ b/pkg/front_end/testcases/generic_metadata/from_dill/main_lib.dart
@@ -0,0 +1,53 @@
+// 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.
+
+typedef exp1 = T Function<T>(T);
+typedef exp2 = void Function<T>();
+typedef exp3 = T Function<T>();
+typedef exp4 = void Function<T>(T);
+typedef exp5 = T Function<T extends S Function<S>(S)>(T);
+typedef exp6 = T Function<T, S>(
+    T, S, V Function<V extends S, U>(T, U, V, Map<S, U>));
+
+class C1<X extends T Function<T>(T)> {
+  C1() {
+    expect(exp1, X);
+  }
+}
+
+class C2<X extends void Function<T>()> {
+  C2() {
+    expect(exp2, X);
+  }
+}
+
+class C3<X extends T Function<T>()> {
+  C3() {
+    expect(exp3, X);
+  }
+}
+
+class C4<X extends void Function<T>(T)> {
+  C4() {
+    expect(exp4, X);
+  }
+}
+
+class C5<X extends T Function<T extends S Function<S>(S)>(T)> {
+  C5() {
+    expect(exp5, X);
+  }
+}
+
+class C6<
+    X extends T Function<T, S>(
+        T, S, V Function<V extends S, U>(T, U, V, Map<S, U>))> {
+  C6() {
+    expect(exp6, X);
+  }
+}
+
+expect(expected, actual) {
+  if (expected != actual) throw 'Expected $expected, actual $actual';
+}
diff --git a/pkg/front_end/testcases/generic_metadata/from_dill/test.options b/pkg/front_end/testcases/generic_metadata/from_dill/test.options
new file mode 100644
index 0000000..bfe6dc8
--- /dev/null
+++ b/pkg/front_end/testcases/generic_metadata/from_dill/test.options
@@ -0,0 +1 @@
+main_lib.dart
\ No newline at end of file
diff --git a/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart
new file mode 100644
index 0000000..30966c9
--- /dev/null
+++ b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart
@@ -0,0 +1,57 @@
+// 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.
+
+import 'nullable_supertypes.dart' as prefix;
+
+class A {}
+class B {}
+class C {}
+
+typedef AAlias = A?;
+typedef BAlias = B?;
+typedef CAlias = C?;
+typedef TAlias<T> = T?;
+
+class C1 extends AAlias {}
+
+class C2 implements AAlias {}
+
+class C3 = A with BAlias;
+
+class C4 = A with B implements CAlias;
+
+class C5 extends A with BAlias {}
+
+mixin M1 on AAlias {}
+
+mixin M2 on A, BAlias {}
+
+mixin M3 on A implements BAlias {}
+
+class D1 extends TAlias<A> {}
+
+class D1a extends prefix.TAlias<A> {}
+
+class D1b extends TAlias<prefix.A> {}
+
+class D2 implements TAlias<A> {}
+
+class D3 = A with TAlias<B>;
+
+class D4 = A with B implements TAlias<C>;
+
+class D5 extends A with TAlias<B> {}
+
+mixin N1 on TAlias<A> {}
+
+mixin N1a on prefix.TAlias<A> {}
+
+mixin N1b on TAlias<prefix.A> {}
+
+mixin N2 on A, TAlias<B> {}
+
+mixin N3 on A implements TAlias<B> {}
+
+main() {
+}
diff --git a/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.strong.expect b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.strong.expect
new file mode 100644
index 0000000..1a2fe24
--- /dev/null
+++ b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.strong.expect
@@ -0,0 +1,383 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:32:18: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1 extends TAlias<A> {}
+//                  ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:34:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1a extends prefix.TAlias<A> {}
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:36:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1b extends TAlias<prefix.A> {}
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:38:21: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D2 implements TAlias<A> {}
+//                     ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D3 = A with TAlias<B>;
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:7: Error: The type 'TAlias' can't be mixed in.
+// class D3 = A with TAlias<B>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:42:32: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D4 = A with B implements TAlias<C>;
+//                                ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:25: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D5 extends A with TAlias<B> {}
+//                         ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:7: Error: The type 'TAlias' can't be mixed in.
+// class D5 extends A with TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:46:13: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1 on TAlias<A> {}
+//             ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:48:14: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1a on prefix.TAlias<A> {}
+//              ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:50:14: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1b on TAlias<prefix.A> {}
+//              ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:52:16: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N2 on A, TAlias<B> {}
+//                ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:54:26: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N3 on A implements TAlias<B> {}
+//                          ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:16:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C1 extends AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:18:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C2 implements AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:20:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C3 = A with BAlias;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:22:7: Error: The type 'CAlias' which is an alias of 'C?' can't be used as supertype because it is nullable.
+//  - 'C' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C4 = A with B implements CAlias;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:13:9: Context: The issue arises via this type alias.
+// typedef CAlias = C?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:24:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C5 extends A with BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:26:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M1 on AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:28:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M2 on A, BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:30:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M3 on A implements BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:32:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1 extends TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:34:7: Error: The type 'prefix.TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1a extends prefix.TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:36:7: Error: The type 'TAlias<prefix.A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1b extends TAlias<prefix.A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:38:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D2 implements TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D3 = A with TAlias<B>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:42:7: Error: The type 'TAlias<C>' which is an alias of 'C?' can't be used as supertype because it is nullable.
+//  - 'C' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D4 = A with B implements TAlias<C>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D5 extends A with TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:46:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1 on TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:48:7: Error: The type 'prefix.TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1a on prefix.TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:50:7: Error: The type 'TAlias<prefix.A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1b on TAlias<prefix.A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:52:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N2 on A, TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:54:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N3 on A implements TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+import self as self;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///nullable_supertypes.dart" as prefix;
+
+typedef AAlias = self::A?;
+typedef BAlias = self::B?;
+typedef CAlias = self::C?;
+typedef TAlias<T extends core::Object? = dynamic> = T?;
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+}
+class B extends core::Object {
+  synthetic constructor •() → self::B
+    : super core::Object::•()
+    ;
+}
+class C extends core::Object {
+  synthetic constructor •() → self::C
+    : super core::Object::•()
+    ;
+}
+class C1 extends core::Object {
+  synthetic constructor •() → self::C1
+    : super core::Object::•()
+    ;
+}
+class C2 extends core::Object {
+  synthetic constructor •() → self::C2
+    : super core::Object::•()
+    ;
+}
+class C3 extends self::A {
+  synthetic constructor •() → self::C3
+    : super self::A::•()
+    ;
+}
+class C4 = self::A with self::B {
+  synthetic constructor •() → self::C4
+    : super self::A::•()
+    ;
+}
+abstract class _C5&A&BAlias extends self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_C5&A&BAlias
+    : super self::A::•()
+    ;
+}
+class C5 extends self::_C5&A&BAlias {
+  synthetic constructor •() → self::C5
+    : super self::_C5&A&BAlias::•()
+    ;
+}
+abstract class M1 extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class _M2&A&BAlias extends core::Object implements self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_M2&A&BAlias
+    : super core::Object::•()
+    ;
+}
+abstract class M2 extends self::_M2&A&BAlias /*isMixinDeclaration*/  {
+}
+abstract class M3 extends self::A /*isMixinDeclaration*/  {
+}
+class D1 extends core::Object {
+  synthetic constructor •() → self::D1
+    : super core::Object::•()
+    ;
+}
+class D1a extends core::Object {
+  synthetic constructor •() → self::D1a
+    : super core::Object::•()
+    ;
+}
+class D1b extends core::Object {
+  synthetic constructor •() → self::D1b
+    : super core::Object::•()
+    ;
+}
+class D2 extends core::Object {
+  synthetic constructor •() → self::D2
+    : super core::Object::•()
+    ;
+}
+class D3 extends self::A {
+  synthetic constructor •() → self::D3
+    : super self::A::•()
+    ;
+}
+class D4 = self::A with self::B {
+  synthetic constructor •() → self::D4
+    : super self::A::•()
+    ;
+}
+abstract class _D5&A&TAlias extends self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_D5&A&TAlias
+    : super self::A::•()
+    ;
+}
+class D5 extends self::_D5&A&TAlias {
+  synthetic constructor •() → self::D5
+    : super self::_D5&A&TAlias::•()
+    ;
+}
+abstract class N1 extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class N1a extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class N1b extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class _N2&A&TAlias extends core::Object implements self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_N2&A&TAlias
+    : super core::Object::•()
+    ;
+}
+abstract class N2 extends self::_N2&A&TAlias /*isMixinDeclaration*/  {
+}
+abstract class N3 extends self::A /*isMixinDeclaration*/  {
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.strong.transformed.expect b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.strong.transformed.expect
new file mode 100644
index 0000000..5dac514
--- /dev/null
+++ b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.strong.transformed.expect
@@ -0,0 +1,383 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:32:18: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1 extends TAlias<A> {}
+//                  ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:34:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1a extends prefix.TAlias<A> {}
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:36:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1b extends TAlias<prefix.A> {}
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:38:21: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D2 implements TAlias<A> {}
+//                     ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D3 = A with TAlias<B>;
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:7: Error: The type 'TAlias' can't be mixed in.
+// class D3 = A with TAlias<B>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:42:32: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D4 = A with B implements TAlias<C>;
+//                                ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:25: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D5 extends A with TAlias<B> {}
+//                         ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:7: Error: The type 'TAlias' can't be mixed in.
+// class D5 extends A with TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:46:13: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1 on TAlias<A> {}
+//             ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:48:14: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1a on prefix.TAlias<A> {}
+//              ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:50:14: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1b on TAlias<prefix.A> {}
+//              ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:52:16: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N2 on A, TAlias<B> {}
+//                ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:54:26: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N3 on A implements TAlias<B> {}
+//                          ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:16:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C1 extends AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:18:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C2 implements AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:20:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C3 = A with BAlias;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:22:7: Error: The type 'CAlias' which is an alias of 'C?' can't be used as supertype because it is nullable.
+//  - 'C' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C4 = A with B implements CAlias;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:13:9: Context: The issue arises via this type alias.
+// typedef CAlias = C?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:24:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C5 extends A with BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:26:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M1 on AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:28:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M2 on A, BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:30:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M3 on A implements BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:32:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1 extends TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:34:7: Error: The type 'prefix.TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1a extends prefix.TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:36:7: Error: The type 'TAlias<prefix.A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1b extends TAlias<prefix.A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:38:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D2 implements TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D3 = A with TAlias<B>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:42:7: Error: The type 'TAlias<C>' which is an alias of 'C?' can't be used as supertype because it is nullable.
+//  - 'C' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D4 = A with B implements TAlias<C>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D5 extends A with TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:46:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1 on TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:48:7: Error: The type 'prefix.TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1a on prefix.TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:50:7: Error: The type 'TAlias<prefix.A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1b on TAlias<prefix.A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:52:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N2 on A, TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:54:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N3 on A implements TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+import self as self;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///nullable_supertypes.dart" as prefix;
+
+typedef AAlias = self::A?;
+typedef BAlias = self::B?;
+typedef CAlias = self::C?;
+typedef TAlias<T extends core::Object? = dynamic> = T?;
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+}
+class B extends core::Object {
+  synthetic constructor •() → self::B
+    : super core::Object::•()
+    ;
+}
+class C extends core::Object {
+  synthetic constructor •() → self::C
+    : super core::Object::•()
+    ;
+}
+class C1 extends core::Object {
+  synthetic constructor •() → self::C1
+    : super core::Object::•()
+    ;
+}
+class C2 extends core::Object {
+  synthetic constructor •() → self::C2
+    : super core::Object::•()
+    ;
+}
+class C3 extends self::A {
+  synthetic constructor •() → self::C3
+    : super self::A::•()
+    ;
+}
+class C4 extends self::A implements self::B /*isEliminatedMixin*/  {
+  synthetic constructor •() → self::C4
+    : super self::A::•()
+    ;
+}
+abstract class _C5&A&BAlias extends self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_C5&A&BAlias
+    : super self::A::•()
+    ;
+}
+class C5 extends self::_C5&A&BAlias {
+  synthetic constructor •() → self::C5
+    : super self::_C5&A&BAlias::•()
+    ;
+}
+abstract class M1 extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class _M2&A&BAlias extends core::Object implements self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_M2&A&BAlias
+    : super core::Object::•()
+    ;
+}
+abstract class M2 extends self::_M2&A&BAlias /*isMixinDeclaration*/  {
+}
+abstract class M3 extends self::A /*isMixinDeclaration*/  {
+}
+class D1 extends core::Object {
+  synthetic constructor •() → self::D1
+    : super core::Object::•()
+    ;
+}
+class D1a extends core::Object {
+  synthetic constructor •() → self::D1a
+    : super core::Object::•()
+    ;
+}
+class D1b extends core::Object {
+  synthetic constructor •() → self::D1b
+    : super core::Object::•()
+    ;
+}
+class D2 extends core::Object {
+  synthetic constructor •() → self::D2
+    : super core::Object::•()
+    ;
+}
+class D3 extends self::A {
+  synthetic constructor •() → self::D3
+    : super self::A::•()
+    ;
+}
+class D4 extends self::A implements self::B /*isEliminatedMixin*/  {
+  synthetic constructor •() → self::D4
+    : super self::A::•()
+    ;
+}
+abstract class _D5&A&TAlias extends self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_D5&A&TAlias
+    : super self::A::•()
+    ;
+}
+class D5 extends self::_D5&A&TAlias {
+  synthetic constructor •() → self::D5
+    : super self::_D5&A&TAlias::•()
+    ;
+}
+abstract class N1 extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class N1a extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class N1b extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class _N2&A&TAlias extends core::Object implements self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_N2&A&TAlias
+    : super core::Object::•()
+    ;
+}
+abstract class N2 extends self::_N2&A&TAlias /*isMixinDeclaration*/  {
+}
+abstract class N3 extends self::A /*isMixinDeclaration*/  {
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.textual_outline.expect b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.textual_outline.expect
new file mode 100644
index 0000000..fbfa19f
--- /dev/null
+++ b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.textual_outline.expect
@@ -0,0 +1,29 @@
+import 'nullable_supertypes.dart' as prefix;
+class A {}
+class B {}
+class C {}
+typedef AAlias = A?;
+typedef BAlias = B?;
+typedef CAlias = C?;
+typedef TAlias<T> = T?;
+class C1 extends AAlias {}
+class C2 implements AAlias {}
+class C3 = A with BAlias;
+class C4 = A with B implements CAlias;
+class C5 extends A with BAlias {}
+mixin M1 on AAlias {}
+mixin M2 on A, BAlias {}
+mixin M3 on A implements BAlias {}
+class D1 extends TAlias<A> {}
+class D1a extends prefix.TAlias<A> {}
+class D1b extends TAlias<prefix.A> {}
+class D2 implements TAlias<A> {}
+class D3 = A with TAlias<B>;
+class D4 = A with B implements TAlias<C>;
+class D5 extends A with TAlias<B> {}
+mixin N1 on TAlias<A> {}
+mixin N1a on prefix.TAlias<A> {}
+mixin N1b on TAlias<prefix.A> {}
+mixin N2 on A, TAlias<B> {}
+mixin N3 on A implements TAlias<B> {}
+main() {}
diff --git a/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.weak.expect b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.weak.expect
new file mode 100644
index 0000000..1a2fe24
--- /dev/null
+++ b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.weak.expect
@@ -0,0 +1,383 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:32:18: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1 extends TAlias<A> {}
+//                  ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:34:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1a extends prefix.TAlias<A> {}
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:36:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1b extends TAlias<prefix.A> {}
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:38:21: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D2 implements TAlias<A> {}
+//                     ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D3 = A with TAlias<B>;
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:7: Error: The type 'TAlias' can't be mixed in.
+// class D3 = A with TAlias<B>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:42:32: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D4 = A with B implements TAlias<C>;
+//                                ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:25: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D5 extends A with TAlias<B> {}
+//                         ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:7: Error: The type 'TAlias' can't be mixed in.
+// class D5 extends A with TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:46:13: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1 on TAlias<A> {}
+//             ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:48:14: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1a on prefix.TAlias<A> {}
+//              ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:50:14: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1b on TAlias<prefix.A> {}
+//              ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:52:16: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N2 on A, TAlias<B> {}
+//                ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:54:26: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N3 on A implements TAlias<B> {}
+//                          ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:16:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C1 extends AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:18:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C2 implements AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:20:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C3 = A with BAlias;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:22:7: Error: The type 'CAlias' which is an alias of 'C?' can't be used as supertype because it is nullable.
+//  - 'C' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C4 = A with B implements CAlias;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:13:9: Context: The issue arises via this type alias.
+// typedef CAlias = C?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:24:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C5 extends A with BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:26:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M1 on AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:28:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M2 on A, BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:30:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M3 on A implements BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:32:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1 extends TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:34:7: Error: The type 'prefix.TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1a extends prefix.TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:36:7: Error: The type 'TAlias<prefix.A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1b extends TAlias<prefix.A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:38:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D2 implements TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D3 = A with TAlias<B>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:42:7: Error: The type 'TAlias<C>' which is an alias of 'C?' can't be used as supertype because it is nullable.
+//  - 'C' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D4 = A with B implements TAlias<C>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D5 extends A with TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:46:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1 on TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:48:7: Error: The type 'prefix.TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1a on prefix.TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:50:7: Error: The type 'TAlias<prefix.A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1b on TAlias<prefix.A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:52:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N2 on A, TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:54:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N3 on A implements TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+import self as self;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///nullable_supertypes.dart" as prefix;
+
+typedef AAlias = self::A?;
+typedef BAlias = self::B?;
+typedef CAlias = self::C?;
+typedef TAlias<T extends core::Object? = dynamic> = T?;
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+}
+class B extends core::Object {
+  synthetic constructor •() → self::B
+    : super core::Object::•()
+    ;
+}
+class C extends core::Object {
+  synthetic constructor •() → self::C
+    : super core::Object::•()
+    ;
+}
+class C1 extends core::Object {
+  synthetic constructor •() → self::C1
+    : super core::Object::•()
+    ;
+}
+class C2 extends core::Object {
+  synthetic constructor •() → self::C2
+    : super core::Object::•()
+    ;
+}
+class C3 extends self::A {
+  synthetic constructor •() → self::C3
+    : super self::A::•()
+    ;
+}
+class C4 = self::A with self::B {
+  synthetic constructor •() → self::C4
+    : super self::A::•()
+    ;
+}
+abstract class _C5&A&BAlias extends self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_C5&A&BAlias
+    : super self::A::•()
+    ;
+}
+class C5 extends self::_C5&A&BAlias {
+  synthetic constructor •() → self::C5
+    : super self::_C5&A&BAlias::•()
+    ;
+}
+abstract class M1 extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class _M2&A&BAlias extends core::Object implements self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_M2&A&BAlias
+    : super core::Object::•()
+    ;
+}
+abstract class M2 extends self::_M2&A&BAlias /*isMixinDeclaration*/  {
+}
+abstract class M3 extends self::A /*isMixinDeclaration*/  {
+}
+class D1 extends core::Object {
+  synthetic constructor •() → self::D1
+    : super core::Object::•()
+    ;
+}
+class D1a extends core::Object {
+  synthetic constructor •() → self::D1a
+    : super core::Object::•()
+    ;
+}
+class D1b extends core::Object {
+  synthetic constructor •() → self::D1b
+    : super core::Object::•()
+    ;
+}
+class D2 extends core::Object {
+  synthetic constructor •() → self::D2
+    : super core::Object::•()
+    ;
+}
+class D3 extends self::A {
+  synthetic constructor •() → self::D3
+    : super self::A::•()
+    ;
+}
+class D4 = self::A with self::B {
+  synthetic constructor •() → self::D4
+    : super self::A::•()
+    ;
+}
+abstract class _D5&A&TAlias extends self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_D5&A&TAlias
+    : super self::A::•()
+    ;
+}
+class D5 extends self::_D5&A&TAlias {
+  synthetic constructor •() → self::D5
+    : super self::_D5&A&TAlias::•()
+    ;
+}
+abstract class N1 extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class N1a extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class N1b extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class _N2&A&TAlias extends core::Object implements self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_N2&A&TAlias
+    : super core::Object::•()
+    ;
+}
+abstract class N2 extends self::_N2&A&TAlias /*isMixinDeclaration*/  {
+}
+abstract class N3 extends self::A /*isMixinDeclaration*/  {
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.weak.outline.expect b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.weak.outline.expect
new file mode 100644
index 0000000..a0cf738
--- /dev/null
+++ b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.weak.outline.expect
@@ -0,0 +1,371 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:32:18: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1 extends TAlias<A> {}
+//                  ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:34:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1a extends prefix.TAlias<A> {}
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:36:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1b extends TAlias<prefix.A> {}
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:38:21: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D2 implements TAlias<A> {}
+//                     ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D3 = A with TAlias<B>;
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:7: Error: The type 'TAlias' can't be mixed in.
+// class D3 = A with TAlias<B>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:42:32: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D4 = A with B implements TAlias<C>;
+//                                ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:25: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D5 extends A with TAlias<B> {}
+//                         ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:7: Error: The type 'TAlias' can't be mixed in.
+// class D5 extends A with TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:46:13: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1 on TAlias<A> {}
+//             ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:48:14: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1a on prefix.TAlias<A> {}
+//              ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:50:14: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1b on TAlias<prefix.A> {}
+//              ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:52:16: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N2 on A, TAlias<B> {}
+//                ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:54:26: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N3 on A implements TAlias<B> {}
+//                          ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:16:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C1 extends AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:18:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C2 implements AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:20:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C3 = A with BAlias;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:22:7: Error: The type 'CAlias' which is an alias of 'C?' can't be used as supertype because it is nullable.
+//  - 'C' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C4 = A with B implements CAlias;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:13:9: Context: The issue arises via this type alias.
+// typedef CAlias = C?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:24:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C5 extends A with BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:26:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M1 on AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:28:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M2 on A, BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:30:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M3 on A implements BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:32:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1 extends TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:34:7: Error: The type 'prefix.TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1a extends prefix.TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:36:7: Error: The type 'TAlias<prefix.A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1b extends TAlias<prefix.A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:38:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D2 implements TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D3 = A with TAlias<B>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:42:7: Error: The type 'TAlias<C>' which is an alias of 'C?' can't be used as supertype because it is nullable.
+//  - 'C' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D4 = A with B implements TAlias<C>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D5 extends A with TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:46:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1 on TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:48:7: Error: The type 'prefix.TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1a on prefix.TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:50:7: Error: The type 'TAlias<prefix.A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1b on TAlias<prefix.A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:52:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N2 on A, TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:54:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N3 on A implements TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+import self as self;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///nullable_supertypes.dart" as prefix;
+
+typedef AAlias = self::A?;
+typedef BAlias = self::B?;
+typedef CAlias = self::C?;
+typedef TAlias<T extends core::Object? = dynamic> = T?;
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    ;
+}
+class B extends core::Object {
+  synthetic constructor •() → self::B
+    ;
+}
+class C extends core::Object {
+  synthetic constructor •() → self::C
+    ;
+}
+class C1 extends core::Object {
+  synthetic constructor •() → self::C1
+    ;
+}
+class C2 extends core::Object {
+  synthetic constructor •() → self::C2
+    ;
+}
+class C3 extends self::A {
+  synthetic constructor •() → self::C3
+    : super self::A::•()
+    ;
+}
+class C4 = self::A with self::B {
+  synthetic constructor •() → self::C4
+    : super self::A::•()
+    ;
+}
+abstract class _C5&A&BAlias extends self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_C5&A&BAlias
+    : super self::A::•()
+    ;
+}
+class C5 extends self::_C5&A&BAlias {
+  synthetic constructor •() → self::C5
+    ;
+}
+abstract class M1 extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class _M2&A&BAlias extends core::Object implements self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_M2&A&BAlias
+    ;
+}
+abstract class M2 extends self::_M2&A&BAlias /*isMixinDeclaration*/  {
+}
+abstract class M3 extends self::A /*isMixinDeclaration*/  {
+}
+class D1 extends core::Object {
+  synthetic constructor •() → self::D1
+    ;
+}
+class D1a extends core::Object {
+  synthetic constructor •() → self::D1a
+    ;
+}
+class D1b extends core::Object {
+  synthetic constructor •() → self::D1b
+    ;
+}
+class D2 extends core::Object {
+  synthetic constructor •() → self::D2
+    ;
+}
+class D3 extends self::A {
+  synthetic constructor •() → self::D3
+    : super self::A::•()
+    ;
+}
+class D4 = self::A with self::B {
+  synthetic constructor •() → self::D4
+    : super self::A::•()
+    ;
+}
+abstract class _D5&A&TAlias extends self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_D5&A&TAlias
+    : super self::A::•()
+    ;
+}
+class D5 extends self::_D5&A&TAlias {
+  synthetic constructor •() → self::D5
+    ;
+}
+abstract class N1 extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class N1a extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class N1b extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class _N2&A&TAlias extends core::Object implements self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_N2&A&TAlias
+    ;
+}
+abstract class N2 extends self::_N2&A&TAlias /*isMixinDeclaration*/  {
+}
+abstract class N3 extends self::A /*isMixinDeclaration*/  {
+}
+static method main() → dynamic
+  ;
diff --git a/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.weak.transformed.expect b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.weak.transformed.expect
new file mode 100644
index 0000000..5dac514
--- /dev/null
+++ b/pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart.weak.transformed.expect
@@ -0,0 +1,383 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:32:18: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1 extends TAlias<A> {}
+//                  ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:34:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1a extends prefix.TAlias<A> {}
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:36:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D1b extends TAlias<prefix.A> {}
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:38:21: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D2 implements TAlias<A> {}
+//                     ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:19: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D3 = A with TAlias<B>;
+//                   ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:7: Error: The type 'TAlias' can't be mixed in.
+// class D3 = A with TAlias<B>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:42:32: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D4 = A with B implements TAlias<C>;
+//                                ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:25: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// class D5 extends A with TAlias<B> {}
+//                         ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:7: Error: The type 'TAlias' can't be mixed in.
+// class D5 extends A with TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:46:13: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1 on TAlias<A> {}
+//             ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:48:14: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1a on prefix.TAlias<A> {}
+//              ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:50:14: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N1b on TAlias<prefix.A> {}
+//              ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:52:16: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N2 on A, TAlias<B> {}
+//                ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:54:26: Error: Can't use a typedef denoting a type variable as a constructor, nor for a static member access.
+// mixin N3 on A implements TAlias<B> {}
+//                          ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:16: Context: This is the type variable ultimately denoted.
+// typedef TAlias<T> = T?;
+//                ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:16:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C1 extends AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:18:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C2 implements AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:20:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C3 = A with BAlias;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:22:7: Error: The type 'CAlias' which is an alias of 'C?' can't be used as supertype because it is nullable.
+//  - 'C' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C4 = A with B implements CAlias;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:13:9: Context: The issue arises via this type alias.
+// typedef CAlias = C?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:24:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class C5 extends A with BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:26:7: Error: The type 'AAlias' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M1 on AAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:11:9: Context: The issue arises via this type alias.
+// typedef AAlias = A?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:28:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M2 on A, BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:30:7: Error: The type 'BAlias' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin M3 on A implements BAlias {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:12:9: Context: The issue arises via this type alias.
+// typedef BAlias = B?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:32:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1 extends TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:34:7: Error: The type 'prefix.TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1a extends prefix.TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:36:7: Error: The type 'TAlias<prefix.A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D1b extends TAlias<prefix.A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:38:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D2 implements TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:40:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D3 = A with TAlias<B>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:42:7: Error: The type 'TAlias<C>' which is an alias of 'C?' can't be used as supertype because it is nullable.
+//  - 'C' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D4 = A with B implements TAlias<C>;
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:44:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// class D5 extends A with TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:46:7: Error: The type 'TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1 on TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:48:7: Error: The type 'prefix.TAlias<A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1a on prefix.TAlias<A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:50:7: Error: The type 'TAlias<prefix.A>' which is an alias of 'A?' can't be used as supertype because it is nullable.
+//  - 'A' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N1b on TAlias<prefix.A> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:52:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N2 on A, TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:54:7: Error: The type 'TAlias<B>' which is an alias of 'B?' can't be used as supertype because it is nullable.
+//  - 'B' is from 'pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart'.
+// mixin N3 on A implements TAlias<B> {}
+//       ^
+// pkg/front_end/testcases/nonfunction_type_aliases/nullable_supertypes.dart:14:9: Context: The issue arises via this type alias.
+// typedef TAlias<T> = T?;
+//         ^
+//
+import self as self;
+import "dart:core" as core;
+
+import "org-dartlang-testcase:///nullable_supertypes.dart" as prefix;
+
+typedef AAlias = self::A?;
+typedef BAlias = self::B?;
+typedef CAlias = self::C?;
+typedef TAlias<T extends core::Object? = dynamic> = T?;
+class A extends core::Object {
+  synthetic constructor •() → self::A
+    : super core::Object::•()
+    ;
+}
+class B extends core::Object {
+  synthetic constructor •() → self::B
+    : super core::Object::•()
+    ;
+}
+class C extends core::Object {
+  synthetic constructor •() → self::C
+    : super core::Object::•()
+    ;
+}
+class C1 extends core::Object {
+  synthetic constructor •() → self::C1
+    : super core::Object::•()
+    ;
+}
+class C2 extends core::Object {
+  synthetic constructor •() → self::C2
+    : super core::Object::•()
+    ;
+}
+class C3 extends self::A {
+  synthetic constructor •() → self::C3
+    : super self::A::•()
+    ;
+}
+class C4 extends self::A implements self::B /*isEliminatedMixin*/  {
+  synthetic constructor •() → self::C4
+    : super self::A::•()
+    ;
+}
+abstract class _C5&A&BAlias extends self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_C5&A&BAlias
+    : super self::A::•()
+    ;
+}
+class C5 extends self::_C5&A&BAlias {
+  synthetic constructor •() → self::C5
+    : super self::_C5&A&BAlias::•()
+    ;
+}
+abstract class M1 extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class _M2&A&BAlias extends core::Object implements self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_M2&A&BAlias
+    : super core::Object::•()
+    ;
+}
+abstract class M2 extends self::_M2&A&BAlias /*isMixinDeclaration*/  {
+}
+abstract class M3 extends self::A /*isMixinDeclaration*/  {
+}
+class D1 extends core::Object {
+  synthetic constructor •() → self::D1
+    : super core::Object::•()
+    ;
+}
+class D1a extends core::Object {
+  synthetic constructor •() → self::D1a
+    : super core::Object::•()
+    ;
+}
+class D1b extends core::Object {
+  synthetic constructor •() → self::D1b
+    : super core::Object::•()
+    ;
+}
+class D2 extends core::Object {
+  synthetic constructor •() → self::D2
+    : super core::Object::•()
+    ;
+}
+class D3 extends self::A {
+  synthetic constructor •() → self::D3
+    : super self::A::•()
+    ;
+}
+class D4 extends self::A implements self::B /*isEliminatedMixin*/  {
+  synthetic constructor •() → self::D4
+    : super self::A::•()
+    ;
+}
+abstract class _D5&A&TAlias extends self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_D5&A&TAlias
+    : super self::A::•()
+    ;
+}
+class D5 extends self::_D5&A&TAlias {
+  synthetic constructor •() → self::D5
+    : super self::_D5&A&TAlias::•()
+    ;
+}
+abstract class N1 extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class N1a extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class N1b extends core::Object /*isMixinDeclaration*/  {
+}
+abstract class _N2&A&TAlias extends core::Object implements self::A /*isAnonymousMixin*/  {
+  synthetic constructor •() → self::_N2&A&TAlias
+    : super core::Object::•()
+    ;
+}
+abstract class N2 extends self::_N2&A&TAlias /*isMixinDeclaration*/  {
+}
+abstract class N3 extends self::A /*isMixinDeclaration*/  {
+}
+static method main() → dynamic {}
diff --git a/pkg/front_end/testcases/textual_outline.status b/pkg/front_end/testcases/textual_outline.status
index b30bc2c..6585a37 100644
--- a/pkg/front_end/testcases/textual_outline.status
+++ b/pkg/front_end/testcases/textual_outline.status
@@ -132,6 +132,7 @@
 nonfunction_type_aliases/issue41501: FormatterCrash
 nonfunction_type_aliases/issue42446: FormatterCrash
 nonfunction_type_aliases/issue45051: FormatterCrash
+nonfunction_type_aliases/nullable_supertypes: FormatterCrash
 nonfunction_type_aliases/unaliased_bounds_checks_in_constructor_calls: FormatterCrash
 rasta/bad_redirection: FormatterCrash
 rasta/issue_000032: FormatterCrash
diff --git a/pkg/kernel/binary.md b/pkg/kernel/binary.md
index eb6976c..b594898 100644
--- a/pkg/kernel/binary.md
+++ b/pkg/kernel/binary.md
@@ -147,7 +147,7 @@
 
 type ComponentFile {
   UInt32 magic = 0x90ABCDEF;
-  UInt32 formatVersion = 59;
+  UInt32 formatVersion = 60;
   Byte[10] shortSdkHash;
   List<String> problemsAsJson; // Described in problems.md.
   Library[] libraries;
diff --git a/pkg/kernel/lib/binary/ast_to_binary.dart b/pkg/kernel/lib/binary/ast_to_binary.dart
index c8c332e..33f0f3e 100644
--- a/pkg/kernel/lib/binary/ast_to_binary.dart
+++ b/pkg/kernel/lib/binary/ast_to_binary.dart
@@ -21,7 +21,7 @@
   VariableIndexer? _variableIndexer;
   LabelIndexer? _labelIndexer;
   SwitchCaseIndexer? _switchCaseIndexer;
-  final TypeParameterIndexer _typeParameterIndexer = new TypeParameterIndexer();
+  TypeParameterIndexer _typeParameterIndexer = new TypeParameterIndexer();
   final StringIndexer stringIndexer;
   late ConstantIndexer _constantIndexer;
   final UriIndexer _sourceUriIndexer = new UriIndexer();
@@ -191,6 +191,8 @@
   }
 
   int writeConstantTableEntry(Constant constant) {
+    TypeParameterIndexer oldTypeParameterIndexer = _typeParameterIndexer;
+    _typeParameterIndexer = new TypeParameterIndexer();
     BufferedSink oldSink = _sink;
     _sink = _constantsSink;
     int initialOffset = _sink.offset;
@@ -263,6 +265,7 @@
       throw new ArgumentError('Unsupported constant $constant');
     }
     _sink = oldSink;
+    _typeParameterIndexer = oldTypeParameterIndexer;
     return _constantsSink.offset - initialOffset;
   }
 
diff --git a/pkg/kernel/lib/binary/tag.dart b/pkg/kernel/lib/binary/tag.dart
index 5e9fa25..fca44c6 100644
--- a/pkg/kernel/lib/binary/tag.dart
+++ b/pkg/kernel/lib/binary/tag.dart
@@ -174,7 +174,7 @@
   /// Internal version of kernel binary format.
   /// Bump it when making incompatible changes in kernel binaries.
   /// Keep in sync with runtime/vm/kernel_binary.h, pkg/kernel/binary.md.
-  static const int BinaryFormatVersion = 59;
+  static const int BinaryFormatVersion = 60;
 }
 
 abstract class ConstantTag {
diff --git a/runtime/vm/compiler/frontend/constant_reader.cc b/runtime/vm/compiler/frontend/constant_reader.cc
index 215ced2..b75d8cb 100644
--- a/runtime/vm/compiler/frontend/constant_reader.cc
+++ b/runtime/vm/compiler/frontend/constant_reader.cc
@@ -201,8 +201,9 @@
           Class::Handle(Z, corelib.LookupClassAllowPrivate(Symbols::_List()));
       // Build type from the raw bytes (needs temporary translator).
       TypeTranslator type_translator(
-          &reader, this, active_class_, true,
-          active_class_->RequireConstCanonicalTypeErasure(null_safety));
+          &reader, this, active_class_, /* finalize = */ true,
+          active_class_->RequireConstCanonicalTypeErasure(null_safety),
+          /* in_constant_context = */ true);
       auto& type_arguments =
           TypeArguments::Handle(Z, TypeArguments::New(1, Heap::kOld));
       AbstractType& type = type_translator.BuildType();
@@ -244,8 +245,9 @@
       instance = Instance::New(klass, Heap::kOld);
       // Build type from the raw bytes (needs temporary translator).
       TypeTranslator type_translator(
-          &reader, this, active_class_, true,
-          active_class_->RequireConstCanonicalTypeErasure(null_safety));
+          &reader, this, active_class_, /* finalize = */ true,
+          active_class_->RequireConstCanonicalTypeErasure(null_safety),
+          /* in_constant_context = */ true);
       const intptr_t number_of_type_arguments = reader.ReadUInt();
       if (klass.NumTypeArguments() > 0) {
         auto& type_arguments = TypeArguments::Handle(
@@ -288,8 +290,9 @@
 
       // Build type from the raw bytes (needs temporary translator).
       TypeTranslator type_translator(
-          &reader, this, active_class_, true,
-          active_class_->RequireConstCanonicalTypeErasure(null_safety));
+          &reader, this, active_class_, /* finalize = */ true,
+          active_class_->RequireConstCanonicalTypeErasure(null_safety),
+          /* in_constant_context = */ true);
       const intptr_t number_of_type_arguments = reader.ReadUInt();
       ASSERT(number_of_type_arguments > 0);
       auto& type_arguments = TypeArguments::Handle(
@@ -327,7 +330,10 @@
       // canonicalized to an identical representant independently of the null
       // safety mode currently in use (sound or unsound) or migration state of
       // the declaring library (legacy or opted-in).
-      TypeTranslator type_translator(&reader, this, active_class_, true);
+      TypeTranslator type_translator(&reader, this, active_class_,
+                                     /* finalize = */ true,
+                                     /* apply_canonical_type_erasure = */ false,
+                                     /* in_constant_context = */ true);
       instance = type_translator.BuildType().ptr();
       break;
     }
diff --git a/runtime/vm/compiler/frontend/kernel_translation_helper.cc b/runtime/vm/compiler/frontend/kernel_translation_helper.cc
index 3b5421f..c83e6cb 100644
--- a/runtime/vm/compiler/frontend/kernel_translation_helper.cc
+++ b/runtime/vm/compiler/frontend/kernel_translation_helper.cc
@@ -2926,7 +2926,8 @@
                                ConstantReader* constant_reader,
                                ActiveClass* active_class,
                                bool finalize,
-                               bool apply_canonical_type_erasure)
+                               bool apply_canonical_type_erasure,
+                               bool in_constant_context)
     : helper_(helper),
       constant_reader_(constant_reader),
       translation_helper_(helper->translation_helper_),
@@ -2937,7 +2938,8 @@
       zone_(translation_helper_.zone()),
       result_(AbstractType::Handle(translation_helper_.zone())),
       finalize_(finalize),
-      apply_canonical_type_erasure_(apply_canonical_type_erasure) {}
+      apply_canonical_type_erasure_(apply_canonical_type_erasure),
+      in_constant_context_(in_constant_context) {}
 
 AbstractType& TypeTranslator::BuildType() {
   BuildTypeInternal();
@@ -3152,73 +3154,76 @@
   intptr_t parameter_index = helper_->ReadUInt();  // read parameter index.
   helper_->SkipOptionalDartType();                 // read bound.
 
-  const TypeArguments& class_types =
-      TypeArguments::Handle(Z, active_class_->klass->type_parameters());
-  if (parameter_index < class_types.Length()) {
-    // The index of the type parameter in [parameters] is
-    // the same index into the `klass->type_parameters()` array.
-    const auto& type_param =
-        TypeParameter::CheckedHandle(Z, class_types.TypeAt(parameter_index));
-    result_ = type_param.ToNullability(nullability, Heap::kOld);
-    active_class_->RecordDerivedTypeParameter(Z, type_param,
-                                              TypeParameter::Cast(result_));
-    return;
-  }
-  parameter_index -= class_types.Length();
-
-  if (active_class_->HasMember()) {
-    if (active_class_->MemberIsFactoryProcedure()) {
-      //
-      // WARNING: This is a little hackish:
-      //
-      // We have a static factory constructor. The kernel IR gives the factory
-      // constructor function its own type parameters (which are equal in name
-      // and number to the ones of the enclosing class). I.e.,
-      //
-      //   class A<T> {
-      //     factory A.x() { return new B<T>(); }
-      //   }
-      //
-      //  is basically translated to this:
-      //
-      //   class A<T> {
-      //     static A.x<T'>() { return new B<T'>(); }
-      //   }
-      //
-      if (class_types.Length() > parameter_index) {
-        const auto& type_param = TypeParameter::CheckedHandle(
-            Z, class_types.TypeAt(parameter_index));
-        result_ = type_param.ToNullability(nullability, Heap::kOld);
-        active_class_->RecordDerivedTypeParameter(Z, type_param,
-                                                  TypeParameter::Cast(result_));
-        return;
-      }
-      parameter_index -= class_types.Length();
+  // If the type is from a constant, the parameter index isn't offset by the
+  // enclosing context.
+  if (!in_constant_context_) {
+    const TypeArguments& class_types =
+        TypeArguments::Handle(Z, active_class_->klass->type_parameters());
+    if (parameter_index < class_types.Length()) {
+      // The index of the type parameter in [parameters] is
+      // the same index into the `klass->type_parameters()` array.
+      const auto& type_param =
+          TypeParameter::CheckedHandle(Z, class_types.TypeAt(parameter_index));
+      result_ = type_param.ToNullability(nullability, Heap::kOld);
+      active_class_->RecordDerivedTypeParameter(Z, type_param,
+                                                TypeParameter::Cast(result_));
+      return;
     }
-    // Factory function should not be considered as procedure.
-    intptr_t procedure_type_parameter_count =
-        (active_class_->MemberIsProcedure() &&
-         !active_class_->MemberIsFactoryProcedure())
-            ? active_class_->MemberTypeParameterCount(Z)
-            : 0;
-    if (procedure_type_parameter_count > 0) {
-      if (procedure_type_parameter_count > parameter_index) {
-        const auto& type_param = TypeParameter::CheckedHandle(
-            Z,
-            TypeArguments::Handle(Z, active_class_->member->type_parameters())
-                .TypeAt(parameter_index));
-        result_ = type_param.ToNullability(nullability, Heap::kOld);
-        active_class_->RecordDerivedTypeParameter(Z, type_param,
-                                                  TypeParameter::Cast(result_));
-        if (finalize_) {
-          result_ = ClassFinalizer::FinalizeType(result_);
+    parameter_index -= class_types.Length();
+
+    if (active_class_->HasMember()) {
+      if (active_class_->MemberIsFactoryProcedure()) {
+        //
+        // WARNING: This is a little hackish:
+        //
+        // We have a static factory constructor. The kernel IR gives the factory
+        // constructor function its own type parameters (which are equal in name
+        // and number to the ones of the enclosing class). I.e.,
+        //
+        //   class A<T> {
+        //     factory A.x() { return new B<T>(); }
+        //   }
+        //
+        //  is basically translated to this:
+        //
+        //   class A<T> {
+        //     static A.x<T'>() { return new B<T'>(); }
+        //   }
+        //
+        if (class_types.Length() > parameter_index) {
+          const auto& type_param = TypeParameter::CheckedHandle(
+              Z, class_types.TypeAt(parameter_index));
+          result_ = type_param.ToNullability(nullability, Heap::kOld);
+          active_class_->RecordDerivedTypeParameter(
+              Z, type_param, TypeParameter::Cast(result_));
+          return;
         }
-        return;
+        parameter_index -= class_types.Length();
       }
-      parameter_index -= procedure_type_parameter_count;
+      // Factory function should not be considered as procedure.
+      intptr_t procedure_type_parameter_count =
+          (active_class_->MemberIsProcedure() &&
+           !active_class_->MemberIsFactoryProcedure())
+              ? active_class_->MemberTypeParameterCount(Z)
+              : 0;
+      if (procedure_type_parameter_count > 0) {
+        if (procedure_type_parameter_count > parameter_index) {
+          const auto& type_param = TypeParameter::CheckedHandle(
+              Z,
+              TypeArguments::Handle(Z, active_class_->member->type_parameters())
+                  .TypeAt(parameter_index));
+          result_ = type_param.ToNullability(nullability, Heap::kOld);
+          active_class_->RecordDerivedTypeParameter(
+              Z, type_param, TypeParameter::Cast(result_));
+          if (finalize_) {
+            result_ = ClassFinalizer::FinalizeType(result_);
+          }
+          return;
+        }
+        parameter_index -= procedure_type_parameter_count;
+      }
     }
   }
-
   if (active_class_->local_type_parameters != NULL) {
     if (parameter_index < active_class_->local_type_parameters->Length()) {
       const auto& type_param = TypeParameter::CheckedHandle(
diff --git a/runtime/vm/compiler/frontend/kernel_translation_helper.h b/runtime/vm/compiler/frontend/kernel_translation_helper.h
index 03e6378..64c5c8d 100644
--- a/runtime/vm/compiler/frontend/kernel_translation_helper.h
+++ b/runtime/vm/compiler/frontend/kernel_translation_helper.h
@@ -1460,7 +1460,8 @@
                  ConstantReader* constant_reader,
                  ActiveClass* active_class,
                  bool finalize = false,
-                 bool apply_canonical_type_erasure = false);
+                 bool apply_canonical_type_erasure = false,
+                 bool in_constant_context = false);
 
   AbstractType& BuildType();
   AbstractType& BuildTypeWithoutFinalization();
@@ -1541,6 +1542,7 @@
   AbstractType& result_;
   bool finalize_;
   const bool apply_canonical_type_erasure_;
+  const bool in_constant_context_;
 
   friend class ScopeBuilder;
   friend class KernelLoader;
diff --git a/runtime/vm/kernel_binary.h b/runtime/vm/kernel_binary.h
index 2e1eee9..29eae67 100644
--- a/runtime/vm/kernel_binary.h
+++ b/runtime/vm/kernel_binary.h
@@ -20,8 +20,8 @@
 static const uint32_t kMagicProgramFile = 0x90ABCDEFu;
 
 // Both version numbers are inclusive.
-static const uint32_t kMinSupportedKernelFormatVersion = 59;
-static const uint32_t kMaxSupportedKernelFormatVersion = 59;
+static const uint32_t kMinSupportedKernelFormatVersion = 60;
+static const uint32_t kMaxSupportedKernelFormatVersion = 60;
 
 // Keep in sync with package:kernel/lib/binary/tag.dart
 #define KERNEL_TAG_LIST(V)                                                     \
diff --git a/tools/VERSION b/tools/VERSION
index 9433708..9f2ecc3 100644
--- a/tools/VERSION
+++ b/tools/VERSION
@@ -27,5 +27,5 @@
 MAJOR 2
 MINOR 13
 PATCH 0
-PRERELEASE 185
+PRERELEASE 186
 PRERELEASE_PATCH 0
\ No newline at end of file