| // Copyright (c) 2022, 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 concrete class has Enum as a superinterface |
| /// (directly or transitively) unless it is the corresponding class of an enum |
| /// declaration. (Abstract interfaces and mixins implementing Enum are allowed, |
| /// but only so that they can be used by enum declarations, they can never be |
| /// used to create an instance which implements Enum, but which is not an enum |
| /// value.) |
| /// |
| /// @description Check that mixins implementing Enum are allowed, if they are |
| /// used by enum declarations |
| /// @author sgrekhov@unipro.ru |
| |
| // SharedOptions=--enable-experiment=enhanced-enums |
| |
| abstract class M1 with Enum {} |
| |
| abstract class M2 = Object with Enum; |
| |
| mixin M3 implements Enum {} |
| |
| enum E1 implements M1 { |
| e1, |
| e2; |
| } |
| |
| enum E2 implements M2 { |
| e1, |
| e2; |
| } |
| |
| enum E3 with M3 { |
| e1, |
| e2; |
| } |
| |
| main() { |
| print(E1); |
| print(E2); |
| print(E3); |
| } |