| // Copyright (c) 2023, 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. |
| |
| extension type E1(num it) {} |
| extension type E2(E1 it) implements E1 {} // Ok. |
| extension type E3(int it) implements E1 {} // Ok. |
| extension type E4(E3 it) implements E1 {} // Ok. |
| extension type E5(E3 it) implements E2 {} // Ok. |
| extension type E6(E2 it) implements E3 {} // Error. |
| extension type E7(String it) implements E1 {} // Error. |
