| // 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 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 abstract classes may implement enum |
| /// @author sgrekhov@unipro.ru |
| |
| // SharedOptions=--enable-experiment=enhanced-enums |
| |
| import "../../Utils/expect.dart"; |
| |
| abstract class C implements Enum { |
| int foo(); |
| } |
| |
| enum E implements C { |
| e1, |
| e2; |
| |
| int foo() => this.index; |
| } |
| |
| main() { |
| Expect.equals(0, E.e1.foo()); |
| Expect.equals(1, E.e2.foo()); |
| } |