| // 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. |
| |
| /// @assertion It’s currently a compile-time error for a class to implement, |
| /// extend or mix-in the Enum class. |
| /// |
| /// Because we want to allow interfaces and mixins that are intended to be |
| /// applied to enum declarations, and therefore to assume Enum to be a |
| /// superclass, we loosen that restriction to: |
| /// |
| /// It’s a compile-time error if a non-abstract class implements Enum unless it |
| /// is the implicit class of an enum declaration. |
| /// |
| /// It is a compile-time error if a class implements, extends or mixes-in a |
| /// class declared by an enum declaration. |
| /// |
| /// That allows abstract classes (interfaces) which implements Enum in order to |
| /// have the int index; getter member available, and it allows mixin |
| /// declarations to use Enum as an on type because mixin declarations cannot be |
| /// instantiated directly. |
| /// |
| /// This restriction still ensure enum values are the only object instances |
| /// which implements Enum, while making it valid to declare abstract class |
| /// MyInterface implements Enum and mixin MyMixin on Enum for interfaces and |
| /// mixins intended to be used in declaring enum classes. |
| /// |
| /// @description Check that implicit class of enum declaration implements Enum |
| /// @author sgrekhov@unipro.ru |
| |
| // SharedOptions=--enable-experiment=enhanced-enums |
| |
| import "../../Utils/expect.dart"; |
| |
| enum E1 { |
| e1, |
| e2 |
| } |
| |
| enum E2 { |
| e1(42), |
| e2(0); |
| |
| const E2(int i); |
| } |
| |
| main() { |
| Expect.isTrue(E1.e1 is Enum); |
| Expect.isTrue(E2.e1 is Enum); |
| } |