pkg/front_end/testcases/override_check_accessor_basic.dart

// 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.

class A {}

class B extends A {}

class C {
  void set x(A value) {}
  A get y => null;
}

class D extends C {
  void set x(Object value) {} // Ok
  B get y => null; // Ok
}

class E extends C {
  void set x(B value) {}
  Object get y => null;
}

main() {}