// Copyright (c) 2019, 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.

abstract class A<X> {
  void foo({Iterable<X>? x});
}

class B<Y> implements A<Y> {
  void foo({x}) {}
}

main() {}