| // 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 |
| |
| class A { |
| void foo() {} |
| } |
| |
| abstract class B extends A { |
| // If this class were concrete, there would be a problem, since `new |
| // B().foo(42)` would be statically allowed, but would lead to invalid |
| // arguments being passed to A.foo. But since the class is abstract, there is |
| // no problem. |
| void foo([x]); |
| } |
| |
| class /*@compile-error=unspecified*/ C extends B { |
| // However, there is a problem here because this class is concrete and doesn't |
| // override foo. |
| } |
| |
| void f(B b) { |
| b.foo(); |
| } |
| |
| main() { |
| f(new C()); |
| } |