// 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
library test;

typedef void F<T>(T t);

abstract class A<T> {
  void f(T x, int y);
}

class B<T> implements A<F<T>> {
  void f(F<T> x, int y) {}
}

abstract class I<T> implements A<F<T>> {
  void f(F<T> x, Object y);
}

abstract class C<T> extends B<F<T>> implements I<F<T>> {}

void main() {}