| // Copyright (c) 2017, 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. |
| |
| // @dart = 2.9 |
| |
| import "package:expect/expect.dart"; |
| |
| class A {} |
| |
| class B extends A {} |
| |
| class C { |
| void f(B x) {} |
| } |
| |
| abstract class I { |
| void f(covariant A x); |
| } |
| |
| // D contains a forwarding stub for f which ensures that `x` is type checked. |
| class D extends C implements I {} |
| |
| void checkStubTearoff(dynamic tearoff) { |
| // Since the stub's parameter is covariant, its type should be reified as |
| // Object. |
| Expect.isTrue(tearoff is void Function(Object)); |
| |
| // Verify that the appropriate runtime check occurs. |
| tearoff(new B()); // No error |
| Expect.throwsTypeError(() { |
| tearoff(new A()); |
| }); |
| } |
| |
| main() { |
| // The same forwarding stub should be torn off from D regardless of what |
| // interface is used to tear it off. |
| D d = new D(); |
| C c = d; |
| I i = d; |
| checkStubTearoff(d.f); |
| checkStubTearoff(c.f); |
| checkStubTearoff(i.f); |
| } |