Add supertype to enum classes.

TEST= language/enum/enum_test Change-Id: I83b7fd1c29103c3aa4dc7ad3e41141fb8c62339e Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/203564 Commit-Queue: Lasse R.H. Nielsen <lrn@google.com> Reviewed-by: Brian Wilkerson <brianwilkerson@google.com> Reviewed-by: Konstantin Shcheglov <scheglov@google.com> Reviewed-by: Johnni Winther <johnniwinther@google.com>
2024-10-01 17:02:10 +00:00 · 2021-06-25 14:08:16 +00:00 · 2021-06-25 14:08:16 +00:00 · 43cff26365
parent 253764ebbb
commit 43cff26365
78 changed files with 233 additions and 90 deletions
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@ -4,9 +4,9 @@

 ### `dart:html`

-* [#44319][]: `convertNativeToDart_Dictionary()` now converts objects
-  recursively, this fixes APIs like MediaStreamTrack.getCapabilities
-  that convert between Maps and browser Dictionaries.
+*   [#44319][]: `convertNativeToDart_Dictionary()` now converts objects
+    recursively, this fixes APIs like MediaStreamTrack.getCapabilities
+    that convert between Maps and browser Dictionaries.

 [44319]: (https://github.com/dart-lang/sdk/issues/44319)

@ -23,6 +23,8 @@

 #### `dart:core`

+*   Introduce `Enum` interface implemented by all `enum` declarations.
+
 *   The native `DateTime` class now better handles local time around
    daylight saving changes that are not precisely one hour.
    (No change on the Web which uses the JavaScript `Date` object.)
--- a/pkg/_fe_analyzer_shared/test/inheritance/data/object_opt_in/core.dart
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/object_opt_in/core.dart
@ -24,6 +24,9 @@ class Object {
  String toString() => '';
 }

+/*class: Enum:Enum,Object*/
+abstract class Enum {}
+
 /*class: Null:Null,Object*/
 class Null {
  factory Null._uninstantiable() {
--- a/pkg/_fe_analyzer_shared/test/inheritance/data/object_opt_out/core.dart
+++ b/pkg/_fe_analyzer_shared/test/inheritance/data/object_opt_out/core.dart
@ -26,6 +26,9 @@ class Object {
  String toString() => '';
 }

+/*class: Enum:Enum,Object*/
+abstract class Enum {}
+
 /*class: Null:Null,Object*/
 class Null {
  factory Null._uninstantiable() {
--- a/pkg/analysis_server/test/integration/analysis/get_errors_non_standard_sdk_test.dart
+++ b/pkg/analysis_server/test/integration/analysis/get_errors_non_standard_sdk_test.dart
@ -38,6 +38,7 @@ class double {}
 class int {}
 class num {}
 class Object {}
+class Enum {}
 class Iterable<E> {}
 class Map<K, V> {}
 class Null {}
--- a/pkg/analyzer/lib/dart/element/type_provider.dart
+++ b/pkg/analyzer/lib/dart/element/type_provider.dart
@ -31,6 +31,12 @@ abstract class TypeProvider {
  /// Return the type representing the built-in type `dynamic`.
  DartType get dynamicType;

+  /// Return the element representing the built-in type `Enum`.
+  ClassElement get enumElement;
+
+  /// Return the type representing the built-in type `Enum`.
+  InterfaceType get enumType;
+
  /// Return the type representing the built-in type `Function`.
  InterfaceType get functionType;

--- a/pkg/analyzer/lib/src/dart/element/element.dart
+++ b/pkg/analyzer/lib/src/dart/element/element.dart
@ -2668,7 +2668,8 @@ class EnumElementImpl extends AbstractClassElementImpl {
  }

  @override
-  List<InterfaceType> get allSupertypes => <InterfaceType>[supertype];
+  List<InterfaceType> get allSupertypes =>
+      <InterfaceType>[...interfaces, supertype];

  List<FieldElement> get constants {
    return fields.where((field) => !field.isSynthetic).toList();
@ -2700,7 +2701,8 @@ class EnumElementImpl extends AbstractClassElementImpl {
  bool get hasStaticMember => true;

  @override
-  List<InterfaceType> get interfaces => const <InterfaceType>[];
+  List<InterfaceType> get interfaces =>
+      <InterfaceType>[library.typeProvider.enumType];

  @override
  bool get isAbstract => false;
--- a/pkg/analyzer/lib/src/dart/element/type_provider.dart
+++ b/pkg/analyzer/lib/src/dart/element/type_provider.dart
@ -27,6 +27,7 @@ const Set<String> _nonSubtypableDartAsyncClassNames = {
 const Set<String> _nonSubtypableDartCoreClassNames = {
  'bool',
  'double',
+  'Enum',
  'int',
  'Null',
  'num',
@ -104,6 +105,7 @@ class TypeProviderImpl extends TypeProviderBase {

  ClassElement? _boolElement;
  ClassElement? _doubleElement;
+  ClassElement? _enumElement;
  ClassElement? _futureElement;
  ClassElement? _futureOrElement;
  ClassElement? _intElement;
@ -122,6 +124,7 @@ class TypeProviderImpl extends TypeProviderBase {
  InterfaceType? _deprecatedType;
  InterfaceType? _doubleType;
  InterfaceType? _doubleTypeQuestion;
+  InterfaceType? _enumType;
  InterfaceType? _functionType;
  InterfaceType? _futureDynamicType;
  InterfaceType? _futureNullType;
@ -151,7 +154,7 @@ class TypeProviderImpl extends TypeProviderBase {
    required LibraryElement coreLibrary,
    required LibraryElement asyncLibrary,
    required bool isNonNullableByDefault,
-  })   : _coreLibrary = coreLibrary,
+  })  : _coreLibrary = coreLibrary,
        _asyncLibrary = asyncLibrary,
        isNonNullableByDefault = isNonNullableByDefault;

@ -219,6 +222,16 @@ class TypeProviderImpl extends TypeProviderBase {
  @override
  DartType get dynamicType => DynamicTypeImpl.instance;

+  @override
+  ClassElement get enumElement {
+    return _enumElement ??= _getClassElement(_coreLibrary, "Enum");
+  }
+
+  @override
+  InterfaceType get enumType {
+    return _enumType ??= _getType(_coreLibrary, "Enum");
+  }
+
  @override
  InterfaceType get functionType {
    return _functionType ??= _getType(_coreLibrary, "Function");
--- a/pkg/analyzer/lib/src/test_utilities/mock_sdk.dart
+++ b/pkg/analyzer/lib/src/test_utilities/mock_sdk.dart
@ -523,6 +523,10 @@ class Object {
  external dynamic noSuchMethod(Invocation invocation);
 }

+abstract class Enum {
+  int get index;
+}
+
 abstract class Pattern {
  Iterable<Match> allMatches(String string, [int start = 0]);
 }
--- a/pkg/analyzer/test/src/dart/resolution/enum_test.dart
+++ b/pkg/analyzer/test/src/dart/resolution/enum_test.dart
@ -24,7 +24,7 @@ var v = [E1.a, E2.b];
 ''');

    var v = findElement.topVar('v');
-    assertType(v.type, 'List<Object>');
+    assertType(v.type, 'List<Enum>');
  }

  test_isConstantEvaluated() async {
--- a/pkg/analyzer/test/src/summary/resynthesize_common.dart
+++ b/pkg/analyzer/test/src/summary/resynthesize_common.dart
@ -4624,6 +4624,8 @@ library
      enum E @5
        codeOffset: 0
        codeLength: 26
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -9667,6 +9669,8 @@ library
          synthetic @-1
    enums
      enum E @30
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -11764,6 +11768,8 @@ library
  definingUnit
    enums
      enum E @5
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -11816,6 +11822,8 @@ library
  definingUnit
    enums
      enum E @5
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -14445,6 +14453,8 @@ library
  definingUnit
    enums
      enum E @5
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -14467,6 +14477,8 @@ library
          synthetic toString @-1
            returnType: String
      enum E @19
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -14723,6 +14735,8 @@ library
    enums
      enum E @65
        documentationComment: /**\n * Docs\n */
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -14758,6 +14772,8 @@ library
  definingUnit
    enums
      enum E @5
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -14804,6 +14820,8 @@ library
  definingUnit
    enums
      enum E @5
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -14863,6 +14881,8 @@ library
  definingUnit
    enums
      enum E @5
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -14894,6 +14914,8 @@ library
  definingUnit
    enums
      enum E1 @5
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -14912,6 +14934,8 @@ library
          synthetic toString @-1
            returnType: String
      enum E2 @20
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -14997,6 +15021,8 @@ library
                superKeyword: super @0
    enums
      enum E @5
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -22565,6 +22591,8 @@ library
  definingUnit
    enums
      enum E @19
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -22634,6 +22662,8 @@ library
            returnType: dynamic
    enums
      enum E @64
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -22707,6 +22737,8 @@ library
              staticElement: self::@getter::a
              staticType: null
              token: a @15
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -24202,6 +24234,8 @@ library
              staticElement: self::@getter::foo
              staticType: null
              token: foo @17
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -25392,6 +25426,8 @@ library
          synthetic @-1
    enums
      enum E @5
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -26873,6 +26909,8 @@ library
  definingUnit
    enums
      enum E @5
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -29182,6 +29220,8 @@ library
          synthetic @-1
    enums
      enum E @16
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -29288,6 +29328,8 @@ library
            synthetic @-1
      enums
        enum E @27
+          interfaces
+            Enum
          fields
            synthetic final index @-1
              type: int
@ -29328,6 +29370,8 @@ library
          synthetic @-1
    enums
      enum E @42
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
@ -29405,6 +29449,8 @@ library
            synthetic @-1
      enums
        enum E @27
+          interfaces
+            Enum
          fields
            synthetic final index @-1
              type: int
@ -29480,6 +29526,8 @@ library
            synthetic @-1
      enums
        enum E @27
+          interfaces
+            Enum
          fields
            synthetic final index @-1
              type: int
@ -29623,6 +29671,8 @@ library
  definingUnit
    enums
      enum E @5
+        interfaces
+          Enum
        fields
          synthetic final index @-1
            type: int
--- a/pkg/front_end/lib/src/fasta/builder/enum_builder.dart
+++ b/pkg/front_end/lib/src/fasta/builder/enum_builder.dart
@ -79,6 +79,8 @@ class EnumBuilder extends SourceClassBuilder {

  final NamedTypeBuilder objectType;

+  final NamedTypeBuilder enumType;
+
  final NamedTypeBuilder listType;

  EnumBuilder.internal(
@ -91,6 +93,7 @@ class EnumBuilder extends SourceClassBuilder {
      this.intType,
      this.listType,
      this.objectType,
+      this.enumType,
      this.stringType,
      LibraryBuilder parent,
      int startCharOffset,
@ -151,6 +154,12 @@ class EnumBuilder extends SourceClassBuilder {
        /* arguments = */ null,
        /* fileUri = */ null,
        /* charOffset = */ null);
+    NamedTypeBuilder enumType = new NamedTypeBuilder(
+        "Enum",
+        const NullabilityBuilder.omitted(),
+        /* arguments = */ null,
+        /* fileUri = */ null,
+        /* charOffset = */ null);
    Class cls = new Class(
        name: name, reference: referencesFrom?.reference, fileUri: fileUri);
    Map<String, MemberBuilder> members = <String, MemberBuilder>{};
@ -393,6 +402,7 @@ class EnumBuilder extends SourceClassBuilder {
        intType,
        listType,
        objectType,
+        enumType,
        stringType,
        parent,
        startCharOffsetComputed,
@ -429,8 +439,12 @@ class EnumBuilder extends SourceClassBuilder {
        coreLibrary.scope, charOffset, fileUri, libraryBuilder);
    objectType.resolveIn(
        coreLibrary.scope, charOffset, fileUri, libraryBuilder);
+    enumType.resolveIn(coreLibrary.scope, charOffset, fileUri, libraryBuilder);
    listType.resolveIn(coreLibrary.scope, charOffset, fileUri, libraryBuilder);

+    cls.implementedTypes
+        .add(enumType.buildSupertype(libraryBuilder, charOffset, fileUri));
+
    SourceFieldBuilder indexFieldBuilder = firstMemberNamed("index");
    indexFieldBuilder.build(libraryBuilder);
    Field indexField = indexFieldBuilder.field;
--- a/pkg/front_end/lib/src/fasta/denylisted_classes.dart
+++ b/pkg/front_end/lib/src/fasta/denylisted_classes.dart
@ -8,6 +8,7 @@ const List<String> denylistedCoreClasses = [
  "int",
  "num",
  "double",
+  "Enum",
  "String",
  "Null"
 ];
--- a/pkg/front_end/lib/src/fasta/source/source_loader.dart
+++ b/pkg/front_end/lib/src/fasta/source/source_loader.dart
@ -1578,6 +1578,9 @@ class Object {
  bool operator==(dynamic) {}
 }

+abstract class Enum {
+}
+
 class String {}

 class Symbol {}
--- a/pkg/front_end/testcases/aot/enum_from_lib_used_as_type/main.dart.strong.expect
+++ b/pkg/front_end/testcases/aot/enum_from_lib_used_as_type/main.dart.strong.expect
@ -16,7 +16,7 @@ library /*isNonNullableByDefault*/;
 import self as mai;
 import "dart:core" as core;

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<mai::Enum> values = #C4;
--- a/pkg/front_end/testcases/aot/enum_from_lib_used_as_type/main.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/aot/enum_from_lib_used_as_type/main.dart.strong.transformed.expect
@ -17,7 +17,7 @@ library /*isNonNullableByDefault*/;
 import self as mai;
 import "dart:core" as core;

-abstract class Enum extends core::Object {
+abstract class Enum extends core::Object implements core::Enum {
 }
 class Class extends core::Object {
  synthetic constructor •() → mai::Class
--- a/pkg/front_end/testcases/aot/enum_from_lib_used_as_type/main.dart.weak.expect
+++ b/pkg/front_end/testcases/aot/enum_from_lib_used_as_type/main.dart.weak.expect
@ -16,7 +16,7 @@ library /*isNonNullableByDefault*/;
 import self as mai;
 import "dart:core" as core;

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<mai::Enum> values = #C4;
--- a/pkg/front_end/testcases/aot/enum_from_lib_used_as_type/main.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/aot/enum_from_lib_used_as_type/main.dart.weak.outline.expect
@ -10,7 +10,7 @@ library /*isNonNullableByDefault*/;
 import self as self2;
 import "dart:core" as core;

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self2::Enum> values = #C4;
--- a/pkg/front_end/testcases/aot/enum_from_lib_used_as_type/main.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/aot/enum_from_lib_used_as_type/main.dart.weak.transformed.expect
@ -17,7 +17,7 @@ library /*isNonNullableByDefault*/;
 import self as mai;
 import "dart:core" as core;

-abstract class Enum extends core::Object {
+abstract class Enum extends core::Object implements core::Enum {
  abstract get /*isLegacy*/ index() → core::int;
 }
 class Class extends core::Object {
--- a/pkg/front_end/testcases/aot/tree_shake/main.dart.strong.expect
+++ b/pkg/front_end/testcases/aot/tree_shake/main.dart.strong.expect
@ -5,7 +5,7 @@ import "main_lib.dart" as mai;

 import "org-dartlang-testcase:///main_lib.dart";

-class UnusedEnum extends core::Object /*isEnum*/  {
+class UnusedEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::UnusedEnum> values = #C7;
@ -17,7 +17,7 @@ class UnusedEnum extends core::Object /*isEnum*/  {
  method toString() → core::String
    return this.{self::UnusedEnum::_name}{core::String};
 }
-class UsedEnum extends core::Object /*isEnum*/  {
+class UsedEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::UsedEnum> values = #C12;
@ -67,7 +67,7 @@ library /*isNonNullableByDefault*/;
 import self as mai;
 import "dart:core" as core;

-class ConstEnum extends core::Object /*isEnum*/  {
+class ConstEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<mai::ConstEnum> values = #C15;
--- a/pkg/front_end/testcases/aot/tree_shake/main.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/aot/tree_shake/main.dart.strong.transformed.expect
@ -6,9 +6,9 @@ import "dart:_internal" as _in;

 import "org-dartlang-testcase:///main_lib.dart";

-abstract class UnusedEnum extends core::Object {
+abstract class UnusedEnum extends core::Object implements core::Enum {
 }
-class UsedEnum extends core::Object /*isEnum*/  {
+class UsedEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  method toString() → core::String
@ -43,7 +43,7 @@ library /*isNonNullableByDefault*/;
 import self as mai;
 import "dart:core" as core;

-abstract class ConstEnum extends core::Object {
+abstract class ConstEnum extends core::Object implements core::Enum {
 }
 class ConstClass extends core::Object {
  synthetic constructor •() → mai::ConstClass
--- a/pkg/front_end/testcases/aot/tree_shake/main.dart.weak.expect
+++ b/pkg/front_end/testcases/aot/tree_shake/main.dart.weak.expect
@ -5,7 +5,7 @@ import "main_lib.dart" as mai;

 import "org-dartlang-testcase:///main_lib.dart";

-class UnusedEnum extends core::Object /*isEnum*/  {
+class UnusedEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::UnusedEnum> values = #C7;
@ -17,7 +17,7 @@ class UnusedEnum extends core::Object /*isEnum*/  {
  method toString() → core::String
    return this.{self::UnusedEnum::_name}{core::String};
 }
-class UsedEnum extends core::Object /*isEnum*/  {
+class UsedEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::UsedEnum> values = #C12;
@ -67,7 +67,7 @@ library /*isNonNullableByDefault*/;
 import self as mai;
 import "dart:core" as core;

-class ConstEnum extends core::Object /*isEnum*/  {
+class ConstEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<mai::ConstEnum> values = #C15;
--- a/pkg/front_end/testcases/aot/tree_shake/main.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/aot/tree_shake/main.dart.weak.outline.expect
@ -4,7 +4,7 @@ import "dart:core" as core;

 import "org-dartlang-testcase:///main_lib.dart";

-class UnusedEnum extends core::Object /*isEnum*/  {
+class UnusedEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::UnusedEnum> values = const <self::UnusedEnum>[self::UnusedEnum::a, self::UnusedEnum::b];
@ -16,7 +16,7 @@ class UnusedEnum extends core::Object /*isEnum*/  {
  method toString() → core::String
    return this.{self::UnusedEnum::_name}{core::String};
 }
-class UsedEnum extends core::Object /*isEnum*/  {
+class UsedEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::UsedEnum> values = const <self::UsedEnum>[self::UsedEnum::unusedValue, self::UsedEnum::usedValue];
@ -55,7 +55,7 @@ library /*isNonNullableByDefault*/;
 import self as self2;
 import "dart:core" as core;

-class ConstEnum extends core::Object /*isEnum*/  {
+class ConstEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self2::ConstEnum> values = #C4;
--- a/pkg/front_end/testcases/aot/tree_shake/main.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/aot/tree_shake/main.dart.weak.transformed.expect
@ -6,9 +6,9 @@ import "dart:_internal" as _in;

 import "org-dartlang-testcase:///main_lib.dart";

-abstract class UnusedEnum extends core::Object {
+abstract class UnusedEnum extends core::Object implements core::Enum {
 }
-class UsedEnum extends core::Object /*isEnum*/  {
+class UsedEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  method toString() → core::String
@ -43,7 +43,7 @@ library /*isNonNullableByDefault*/;
 import self as mai;
 import "dart:core" as core;

-abstract class ConstEnum extends core::Object {
+abstract class ConstEnum extends core::Object implements core::Enum {
  abstract get /*isLegacy*/ index() → core::int;
 }
 class ConstClass extends core::Object {
--- a/pkg/front_end/testcases/general/annotation_on_enum_values.dart.weak.expect
+++ b/pkg/front_end/testcases/general/annotation_on_enum_values.dart.weak.expect
@ -18,7 +18,7 @@ class Fisk<T extends core::Object* = dynamic> extends core::Object /*hasConstCon
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Foo extends core::Object /*isEnum*/  {
+class Foo extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Foo*>* values = #C10;
--- a/pkg/front_end/testcases/general/annotation_on_enum_values.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/general/annotation_on_enum_values.dart.weak.outline.expect
@ -18,7 +18,7 @@ class Fisk<T extends core::Object* = dynamic> extends core::Object /*hasConstCon
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Foo extends core::Object /*isEnum*/  {
+class Foo extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Foo*>* values = const <self::Foo*>[self::Foo::bar, self::Foo::baz, self::Foo::cafebabe];
--- a/pkg/front_end/testcases/general/annotation_on_enum_values.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general/annotation_on_enum_values.dart.weak.transformed.expect
@ -18,7 +18,7 @@ class Fisk<T extends core::Object* = dynamic> extends core::Object /*hasConstCon
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Foo extends core::Object /*isEnum*/  {
+class Foo extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Foo*>* values = #C10;
--- a/pkg/front_end/testcases/general/duplicated_declarations.dart.weak.expect
+++ b/pkg/front_end/testcases/general/duplicated_declarations.dart.weak.expect
@ -481,7 +481,7 @@ Try removing the extra positional arguments.
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Enum#4 extends core::Object /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
+class Enum#4 extends core::Object implements core::Enum /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Enum#4*>* values = #C4;
@ -501,7 +501,7 @@ class Enum#4 extends core::Object /*isEnum*/  { // from org-dartlang-testcase://
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Enum#3 extends core::Object /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
+class Enum#3 extends core::Object implements core::Enum /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Enum#3*>* values = #C12;
@ -523,7 +523,7 @@ class Enum#3 extends core::Object /*isEnum*/  { // from org-dartlang-testcase://
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Enum#2 extends core::Object /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
+class Enum#2 extends core::Object implements core::Enum /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Enum#2*>* values = #C17;
@ -545,7 +545,7 @@ class Enum#2 extends core::Object /*isEnum*/  { // from org-dartlang-testcase://
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Enum#1 extends core::Object /*isEnum*/  {
+class Enum#1 extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Enum#1*>* values = #C21;
@ -567,7 +567,7 @@ class Enum#1 extends core::Object /*isEnum*/  {
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Enum*>* values = #C25;
@ -589,7 +589,7 @@ class Enum extends core::Object /*isEnum*/  {
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class AnotherEnum extends core::Object /*isEnum*/  {
+class AnotherEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::AnotherEnum*>* values = #C32;
--- a/pkg/front_end/testcases/general/duplicated_declarations.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/general/duplicated_declarations.dart.weak.outline.expect
@ -419,7 +419,7 @@ class Sub extends core::Object {
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Enum#4 extends core::Object /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
+class Enum#4 extends core::Object implements core::Enum /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Enum#4*>* values = const <self::Enum#4*>[self::Enum#4::a];
@ -439,7 +439,7 @@ class Enum#4 extends core::Object /*isEnum*/  { // from org-dartlang-testcase://
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Enum#3 extends core::Object /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
+class Enum#3 extends core::Object implements core::Enum /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Enum#3*>* values = const <self::Enum#3*>[self::Enum#3::a, self::Enum#3::b, self::Enum#3::c];
@ -461,7 +461,7 @@ class Enum#3 extends core::Object /*isEnum*/  { // from org-dartlang-testcase://
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Enum#2 extends core::Object /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
+class Enum#2 extends core::Object implements core::Enum /*isEnum*/  { // from org-dartlang-testcase:///duplicated_declarations_part.dart
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Enum#2*>* values = const <self::Enum#2*>[self::Enum#2::Enum, self::Enum#2::a, self::Enum#2::b];
@ -483,7 +483,7 @@ class Enum#2 extends core::Object /*isEnum*/  { // from org-dartlang-testcase://
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Enum#1 extends core::Object /*isEnum*/  {
+class Enum#1 extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Enum#1*>* values = const <self::Enum#1*>[self::Enum#1::a, self::Enum#1::b, self::Enum#1::c];
@ -505,7 +505,7 @@ class Enum#1 extends core::Object /*isEnum*/  {
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Enum*>* values = const <self::Enum*>[self::Enum::Enum, self::Enum::a, self::Enum::b];
@ -527,7 +527,7 @@ class Enum extends core::Object /*isEnum*/  {
  abstract member-signature method noSuchMethod(core::Invocation* invocation) → dynamic; -> core::Object::noSuchMethod
  abstract member-signature get runtimeType() → core::Type*; -> core::Object::runtimeType
 }
-class AnotherEnum extends core::Object /*isEnum*/  {
+class AnotherEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::AnotherEnum*>* values = const <self::AnotherEnum*>[self::AnotherEnum::a, self::AnotherEnum::b, self::AnotherEnum::c];
--- a/pkg/front_end/testcases/general/metadata_enum.dart.weak.expect
+++ b/pkg/front_end/testcases/general/metadata_enum.dart.weak.expect
@ -3,7 +3,7 @@ import self as self;
 import "dart:core" as core;

@#C1
-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::E*>* values = #C11;
--- a/pkg/front_end/testcases/general/metadata_enum.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/general/metadata_enum.dart.weak.outline.expect
@ -3,7 +3,7 @@ import self as self;
 import "dart:core" as core;

@self::a
-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::E*>* values = const <self::E*>[self::E::E1, self::E::E2, self::E::E3];
--- a/pkg/front_end/testcases/general/metadata_enum.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/general/metadata_enum.dart.weak.transformed.expect
@ -3,7 +3,7 @@ import self as self;
 import "dart:core" as core;

@#C1
-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::E*>* values = #C11;
--- a/pkg/front_end/testcases/incremental/no_outline_change_2.yaml.world.1.expect
+++ b/pkg/front_end/testcases/incremental/no_outline_change_2.yaml.world.1.expect
@ -30,7 +30,7 @@ library from "org-dartlang-test:///main.dart" as main {
    abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
    abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
  }
-  class CompilationStrategy extends dart.core::Object /*isEnum*/  {
+  class CompilationStrategy extends dart.core::Object implements dart.core::Enum /*isEnum*/  {
    final field dart.core::int* index;
    final field dart.core::String* _name;
    static const field dart.core::List<main::CompilationStrategy*>* values = #C14;
--- a/pkg/front_end/testcases/incremental/no_outline_change_2.yaml.world.2.expect
+++ b/pkg/front_end/testcases/incremental/no_outline_change_2.yaml.world.2.expect
@ -30,7 +30,7 @@ library from "org-dartlang-test:///main.dart" as main {
    abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
    abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
  }
-  class CompilationStrategy extends dart.core::Object /*isEnum*/  {
+  class CompilationStrategy extends dart.core::Object implements dart.core::Enum /*isEnum*/  {
    final field dart.core::int* index;
    final field dart.core::String* _name;
    static const field dart.core::List<main::CompilationStrategy*>* values = #C14;
--- a/pkg/front_end/testcases/incremental/no_outline_change_6.yaml.world.1.expect
+++ b/pkg/front_end/testcases/incremental/no_outline_change_6.yaml.world.1.expect
@ -37,7 +37,7 @@ library from "org-dartlang-test:///main.dart" as main {
    abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
    abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
  }
-  class CompilationStrategy extends dart.core::Object /*isEnum*/  {
+  class CompilationStrategy extends dart.core::Object implements dart.core::Enum /*isEnum*/  {
    final field dart.core::int* index;
    final field dart.core::String* _name;
    static const field dart.core::List<main::CompilationStrategy*>* values = #C14;
--- a/pkg/front_end/testcases/incremental/no_outline_change_6.yaml.world.2.expect
+++ b/pkg/front_end/testcases/incremental/no_outline_change_6.yaml.world.2.expect
@ -37,7 +37,7 @@ library from "org-dartlang-test:///main.dart" as main {
    abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
    abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
  }
-  class CompilationStrategy extends dart.core::Object /*isEnum*/  {
+  class CompilationStrategy extends dart.core::Object implements dart.core::Enum /*isEnum*/  {
    final field dart.core::int* index;
    final field dart.core::String* _name;
    static const field dart.core::List<main::CompilationStrategy*>* values = #C14;
--- a/pkg/front_end/testcases/incremental/no_outline_change_6.yaml.world.3.expect
+++ b/pkg/front_end/testcases/incremental/no_outline_change_6.yaml.world.3.expect
@ -30,7 +30,7 @@ library from "org-dartlang-test:///main.dart" as main {
    abstract member-signature method noSuchMethod(dart.core::Invocation* invocation) → dynamic; -> dart.core::Object::noSuchMethod
    abstract member-signature get runtimeType() → dart.core::Type*; -> dart.core::Object::runtimeType
  }
-  class CompilationStrategy extends dart.core::Object /*isEnum*/  {
+  class CompilationStrategy extends dart.core::Object implements dart.core::Enum /*isEnum*/  {
    final field dart.core::int* index;
    final field dart.core::String* _name;
    static const field dart.core::List<main::CompilationStrategy*>* values = #C14;
--- a/pkg/front_end/testcases/incremental/no_outline_change_7.yaml.world.1.expect
+++ b/pkg/front_end/testcases/incremental/no_outline_change_7.yaml.world.1.expect
@ -42,7 +42,7 @@ library from "org-dartlang-test:///main.dart" as main {
    }
  }
  @#C1
-  class CompilationStrategy extends dart.core::Object /*isEnum*/  {
+  class CompilationStrategy extends dart.core::Object implements dart.core::Enum /*isEnum*/  {
    final field dart.core::int* index;
    final field dart.core::String* _name;
    static const field dart.core::List<main::CompilationStrategy*>* values = #C15;
--- a/pkg/front_end/testcases/incremental/no_outline_change_7.yaml.world.2.expect
+++ b/pkg/front_end/testcases/incremental/no_outline_change_7.yaml.world.2.expect
@ -42,7 +42,7 @@ library from "org-dartlang-test:///main.dart" as main {
    }
  }
  @#C1
-  class CompilationStrategy extends dart.core::Object /*isEnum*/  {
+  class CompilationStrategy extends dart.core::Object implements dart.core::Enum /*isEnum*/  {
    final field dart.core::int* index;
    final field dart.core::String* _name;
    static const field dart.core::List<main::CompilationStrategy*>* values = #C15;
--- a/pkg/front_end/testcases/inference/inferred_type_is_enum.dart.weak.expect
+++ b/pkg/front_end/testcases/inference/inferred_type_is_enum.dart.weak.expect
@ -2,7 +2,7 @@ library test;
 import self as self;
 import "dart:core" as core;

-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::E*>* values = #C4;
--- a/pkg/front_end/testcases/inference/inferred_type_is_enum.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/inference/inferred_type_is_enum.dart.weak.outline.expect
@ -2,7 +2,7 @@ library test;
 import self as self;
 import "dart:core" as core;

-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::E*>* values = const <self::E*>[self::E::v1];
--- a/pkg/front_end/testcases/inference/inferred_type_is_enum.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/inference/inferred_type_is_enum.dart.weak.transformed.expect
@ -2,7 +2,7 @@ library test;
 import self as self;
 import "dart:core" as core;

-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::E*>* values = #C4;
--- a/pkg/front_end/testcases/inference/inferred_type_is_enum_values.dart.weak.expect
+++ b/pkg/front_end/testcases/inference/inferred_type_is_enum_values.dart.weak.expect
@ -2,7 +2,7 @@ library test;
 import self as self;
 import "dart:core" as core;

-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::E*>* values = #C4;
--- a/pkg/front_end/testcases/inference/inferred_type_is_enum_values.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/inference/inferred_type_is_enum_values.dart.weak.outline.expect
@ -2,7 +2,7 @@ library test;
 import self as self;
 import "dart:core" as core;

-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::E*>* values = const <self::E*>[self::E::v1];
--- a/pkg/front_end/testcases/inference/inferred_type_is_enum_values.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/inference/inferred_type_is_enum_values.dart.weak.transformed.expect
@ -2,7 +2,7 @@ library test;
 import self as self;
 import "dart:core" as core;

-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::E*>* values = #C4;
--- a/pkg/front_end/testcases/nnbd/return_null.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/return_null.dart.strong.expect
@ -58,7 +58,7 @@ import "dart:async" as asy;

 import "dart:async";

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::Enum> values = #C7;
--- a/pkg/front_end/testcases/nnbd/return_null.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/return_null.dart.strong.transformed.expect
@ -58,7 +58,7 @@ import "dart:async" as asy;

 import "dart:async";

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::Enum> values = #C7;
--- a/pkg/front_end/testcases/nnbd/return_null.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/return_null.dart.weak.expect
@ -59,7 +59,7 @@ import "dart:_internal" as _in;

 import "dart:async";

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::Enum> values = #C7;
--- a/pkg/front_end/testcases/nnbd/return_null.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/nnbd/return_null.dart.weak.outline.expect
@ -5,7 +5,7 @@ import "dart:async" as asy;

 import "dart:async";

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::Enum> values = const <self::Enum>[self::Enum::a, self::Enum::b];
--- a/pkg/front_end/testcases/nnbd/return_null.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/return_null.dart.weak.transformed.expect
@ -59,7 +59,7 @@ import "dart:_internal" as _in;

 import "dart:async";

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::Enum> values = #C7;
--- a/pkg/front_end/testcases/nnbd/switch_nullable_enum.dart.strong.expect
+++ b/pkg/front_end/testcases/nnbd/switch_nullable_enum.dart.strong.expect
@ -9,7 +9,7 @@ library /*isNonNullableByDefault*/;
 import self as self;
 import "dart:core" as core;

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::Enum> values = #C7;
--- a/pkg/front_end/testcases/nnbd/switch_nullable_enum.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/switch_nullable_enum.dart.strong.transformed.expect
@ -9,7 +9,7 @@ library /*isNonNullableByDefault*/;
 import self as self;
 import "dart:core" as core;

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::Enum> values = #C7;
--- a/pkg/front_end/testcases/nnbd/switch_nullable_enum.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd/switch_nullable_enum.dart.weak.expect
@ -10,7 +10,7 @@ import self as self;
 import "dart:core" as core;
 import "dart:_internal" as _in;

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::Enum> values = #C7;
--- a/pkg/front_end/testcases/nnbd/switch_nullable_enum.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/nnbd/switch_nullable_enum.dart.weak.outline.expect
@ -2,7 +2,7 @@ library /*isNonNullableByDefault*/;
 import self as self;
 import "dart:core" as core;

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::Enum> values = const <self::Enum>[self::Enum::e1, self::Enum::e2];
--- a/pkg/front_end/testcases/nnbd/switch_nullable_enum.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd/switch_nullable_enum.dart.weak.transformed.expect
@ -10,7 +10,7 @@ import self as self;
 import "dart:core" as core;
 import "dart:_internal" as _in;

-class Enum extends core::Object /*isEnum*/  {
+class Enum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::Enum> values = #C7;
--- a/pkg/front_end/testcases/nnbd_mixed/unsound_checks.dart.weak.expect
+++ b/pkg/front_end/testcases/nnbd_mixed/unsound_checks.dart.weak.expect
@ -428,7 +428,7 @@ class OptInClass6b extends core::Object {
    : uns::OptInClass6b::field = field, super core::Object::•()
    ;
 }
-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<uns::E> values = #C8;
--- a/pkg/front_end/testcases/nnbd_mixed/unsound_checks.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/nnbd_mixed/unsound_checks.dart.weak.outline.expect
@ -201,7 +201,7 @@ class OptInClass6b extends core::Object {
  constructor •(core::int field) → self2::OptInClass6b
    ;
 }
-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self2::E> values = const <self2::E>[self2::E::e1, self2::E::e2];
--- a/pkg/front_end/testcases/nnbd_mixed/unsound_checks.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/nnbd_mixed/unsound_checks.dart.weak.transformed.expect
@ -428,7 +428,7 @@ class OptInClass6b extends core::Object {
    : uns::OptInClass6b::field = field, super core::Object::•()
    ;
 }
-class E extends core::Object /*isEnum*/  {
+class E extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<uns::E> values = #C8;
--- a/pkg/front_end/testcases/rasta/enum.dart.weak.expect
+++ b/pkg/front_end/testcases/rasta/enum.dart.weak.expect
@ -2,7 +2,7 @@ library;
 import self as self;
 import "dart:core" as core;

-class Foo extends core::Object /*isEnum*/  {
+class Foo extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Foo*>* values = #C7;
--- a/pkg/front_end/testcases/rasta/enum.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/rasta/enum.dart.weak.outline.expect
@ -2,7 +2,7 @@ library;
 import self as self;
 import "dart:core" as core;

-class Foo extends core::Object /*isEnum*/  {
+class Foo extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Foo*>* values = const <self::Foo*>[self::Foo::ec1, self::Foo::ec2];
--- a/pkg/front_end/testcases/rasta/enum.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/rasta/enum.dart.weak.transformed.expect
@ -2,7 +2,7 @@ library;
 import self as self;
 import "dart:core" as core;

-class Foo extends core::Object /*isEnum*/  {
+class Foo extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int* index;
  final field core::String* _name;
  static const field core::List<self::Foo*>* values = #C7;
--- a/pkg/front_end/testcases/static_field_lowering/enum.dart.strong.expect
+++ b/pkg/front_end/testcases/static_field_lowering/enum.dart.strong.expect
@ -2,7 +2,7 @@ library /*isNonNullableByDefault*/;
 import self as self;
 import "dart:core" as core;

-class A extends core::Object /*isEnum*/  {
+class A extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::A> values = #C7;
--- a/pkg/front_end/testcases/static_field_lowering/enum.dart.strong.transformed.expect
+++ b/pkg/front_end/testcases/static_field_lowering/enum.dart.strong.transformed.expect
@ -2,7 +2,7 @@ library /*isNonNullableByDefault*/;
 import self as self;
 import "dart:core" as core;

-class A extends core::Object /*isEnum*/  {
+class A extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::A> values = #C7;
--- a/pkg/front_end/testcases/static_field_lowering/enum.dart.weak.expect
+++ b/pkg/front_end/testcases/static_field_lowering/enum.dart.weak.expect
@ -2,7 +2,7 @@ library /*isNonNullableByDefault*/;
 import self as self;
 import "dart:core" as core;

-class A extends core::Object /*isEnum*/  {
+class A extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::A> values = #C7;
--- a/pkg/front_end/testcases/static_field_lowering/enum.dart.weak.outline.expect
+++ b/pkg/front_end/testcases/static_field_lowering/enum.dart.weak.outline.expect
@ -2,7 +2,7 @@ library /*isNonNullableByDefault*/;
 import self as self;
 import "dart:core" as core;

-class A extends core::Object /*isEnum*/  {
+class A extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::A> values = const <self::A>[self::A::a, self::A::b];
--- a/pkg/front_end/testcases/static_field_lowering/enum.dart.weak.transformed.expect
+++ b/pkg/front_end/testcases/static_field_lowering/enum.dart.weak.transformed.expect
@ -2,7 +2,7 @@ library /*isNonNullableByDefault*/;
 import self as self;
 import "dart:core" as core;

-class A extends core::Object /*isEnum*/  {
+class A extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::A> values = #C7;
--- a/pkg/vm/testcases/transformations/to_string_transformer/not_transformed.expect
+++ b/pkg/vm/testcases/transformations/to_string_transformer/not_transformed.expect
@ -19,7 +19,7 @@ class Foo extends core::Object implements self::IFoo {
  method toString() → core::String
    return "I am a Foo";
 }
-class FooEnum extends core::Object /*isEnum*/  {
+class FooEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::FooEnum> values = #C11;
--- a/pkg/vm/testcases/transformations/to_string_transformer/transformed.expect
+++ b/pkg/vm/testcases/transformations/to_string_transformer/transformed.expect
@ -19,7 +19,7 @@ class Foo extends core::Object implements self::IFoo {
  method toString() → core::String
    return super.toString();
 }
-class FooEnum extends core::Object /*isEnum*/  {
+class FooEnum extends core::Object implements core::Enum /*isEnum*/  {
  final field core::int index;
  final field core::String _name;
  static const field core::List<self::FooEnum> values = #C11;
--- a/pkg/vm/testcases/transformations/type_flow/transformer/const_prop.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/const_prop.dart.expect
@ -11,7 +11,7 @@ class A extends core::Object {
 [@vm.procedure-attributes.metadata=methodOrSetterCalledDynamically:false,getterCalledDynamically:false,hasThisUses:false,hasTearOffUses:false,methodOrSetterSelectorId:2,getterSelectorId:3]  method getBar() → core::String*
    return "bar";
 }
-class B extends core::Object /*isEnum*/  {
+class B extends core::Object implements core::Enum /*isEnum*/  {
 [@vm.inferred-type.metadata=dart.core::_Smi (value: 1)] [@vm.procedure-attributes.metadata=methodOrSetterCalledDynamically:false,getterCalledDynamically:false,hasThisUses:false,hasNonThisUses:false,hasTearOffUses:false,getterSelectorId:4] [@vm.unboxing-info.metadata=()->i]  final field core::int* index;
 [@vm.inferred-type.metadata=dart.core::_OneByteString (value: "B.b2")] [@vm.procedure-attributes.metadata=methodOrSetterCalledDynamically:false,getterCalledDynamically:false,hasThisUses:false,hasNonThisUses:false,hasTearOffUses:false,getterSelectorId:5]  final field core::String* _name;
 [@vm.procedure-attributes.metadata=methodOrSetterCalledDynamically:false,getterCalledDynamically:false,hasThisUses:false,hasTearOffUses:false,methodOrSetterSelectorId:6,getterSelectorId:7]  method toString() → core::String*
--- a/pkg/vm/testcases/transformations/type_flow/transformer/enum_used_as_type.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/enum_used_as_type.dart.expect
@ -3,7 +3,7 @@ import self as self;
 import "dart:core" as core;
 import "dart:_internal" as _in;

-abstract class Enum extends core::Object {
+abstract class Enum extends core::Object implements core::Enum {
 [@vm.procedure-attributes.metadata=methodOrSetterCalledDynamically:false,getterCalledDynamically:false,hasThisUses:false,hasNonThisUses:false,hasTearOffUses:false,getterSelectorId:1]  abstract get index() → core::int*;
 }
 class Class extends core::Object {
--- a/pkg/vm/testcases/transformations/type_flow/transformer/regress_46461.dart.expect
+++ b/pkg/vm/testcases/transformations/type_flow/transformer/regress_46461.dart.expect
@ -2,7 +2,7 @@ library #lib /*isNonNullableByDefault*/;
 import self as self;
 import "dart:core" as core;

-abstract class A extends core::Object {
+abstract class A extends core::Object implements core::Enum {
 }
 abstract class B extends core::Object {
 [@vm.procedure-attributes.metadata=methodOrSetterCalledDynamically:false,getterCalledDynamically:false,hasThisUses:false,hasNonThisUses:false,hasTearOffUses:false,methodOrSetterSelectorId:1,getterSelectorId:2]  abstract method foo() → void;
--- a/sdk/lib/core/core.dart
+++ b/sdk/lib/core/core.dart
@ -178,6 +178,7 @@ part "comparable.dart";
 part "date_time.dart";
 part "double.dart";
 part "duration.dart";
+part "enum.dart";
 part "errors.dart";
 part "exceptions.dart";
 part "expando.dart";
--- a/sdk/lib/core/core_sources.gni
+++ b/sdk/lib/core/core_sources.gni
@ -13,6 +13,7 @@ core_sdk_sources = [
  "date_time.dart",
  "double.dart",
  "duration.dart",
+  "enum.dart",
  "errors.dart",
  "exceptions.dart",
  "expando.dart",
--- a/sdk/lib/core/enum.dart
+++ b/sdk/lib/core/enum.dart
@ -0,0 +1,23 @@
+// 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.
+
+part of dart.core;
+
+/// An enumerated value.
+///
+/// This class is implemented by all types and values
+/// introduced using an `enum` declaration.
+/// Non-platform classes cannot implement, extend or
+/// mix in this class.
+@Since("2.14")
+abstract class Enum {
+  /// A numeric identifier for the enumerated value.
+  ///
+  /// The values of a single enumeration are numbered
+  /// consecutively from zero to one less than the
+  /// number of values.
+  /// This is also the index of the value in the
+  /// enumerated type's static `values` list.
+  int get index;
+}
--- a/tests/language/enum/enum_test.dart
+++ b/tests/language/enum/enum_test.dart
@ -88,6 +88,11 @@ main() {
    expectIs(value, (e) => e is JSFunctionPrototype);
  }
  Expect.equals(JSFunctionPrototype.length, JSFunctionPrototype.values[0]);
+
+  // Enums implement Enum.
+  Expect.type<Enum>(Enum1._);
+  Enum enumValue = Enum1._;
+  Expect.equals(0, enumValue.index);
 }

 test1(Enum1 e) {
--- a/tests/language/unsorted/inference_enum_list_test.dart
+++ b/tests/language/unsorted/inference_enum_list_test.dart
@ -4,11 +4,12 @@

 enum E1 { a, b }
 enum E2 { a, b }
+enum E3 { a, b }

 var v = [E1.a, E2.b];

 main() {
-  // Test that v is `List<Object>`, so any of these assignemnts are OK.
-  v[0] = 0;
-  v[1] = '1';
+  // Test that v is `List<Enum>`, so these assignments are OK.
+  v[0] = E3.a;
+  List<Enum> w = v;
 }
--- a/tests/language_2/enum/enum_test.dart
+++ b/tests/language_2/enum/enum_test.dart
@ -90,6 +90,11 @@ main() {
    expectIs(value, (e) => e is JSFunctionPrototype);
  }
  Expect.equals(JSFunctionPrototype.length, JSFunctionPrototype.values[0]);
+
+  // Enums implement Enum.
+  Expect.type<Enum>(Enum1._);
+  Enum enumValue = Enum1._;
+  Expect.equals(0, enumValue.index);
 }

 test1(Enum1 e) {
--- a/tests/language_2/unsorted/inference_enum_list_test.dart
+++ b/tests/language_2/unsorted/inference_enum_list_test.dart
@ -6,11 +6,12 @@

 enum E1 { a, b }
 enum E2 { a, b }
+enum E3 { a, b }

 var v = [E1.a, E2.b];

 main() {
-  // Test that v is `List<Object>`, so any of these assignemnts are OK.
-  v[0] = 0;
-  v[1] = '1';
+  // Test that v is `List<Enum>`, so these assignments are OK.
+  v[0] = E3.a;
+  List<Enum> w = v;
 }
--- a/tests/web/internal/mock_libraries.dart
+++ b/tests/web/internal/mock_libraries.dart
@ -50,6 +50,10 @@ import 'dart:_internal' as internal;
        static var nan = 0;
        static parse(s) {}
      }''',
+  'Enum': r'''
+      abstract class Enum {
+        int get index;
+      }''',
  'Function': r'''
      class Function {
        static apply(Function fn, List positional, [Map named]) => null;