// Copyright (c) 2021, 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.

/**
 * @assertion The NORM relation defines the canonical representative of classes
 * of equivalent types...
 * This is based on the following equations:
 *   T?? == T?
 *
 * @description Checks that T?? == T?
 *
 * @author sgrekhov@unipro.ru
 */
// Requirements=nnbd-weak

class T {}
class A<X> {}
class B<X> implements A<X?> {}

class C extends B<T?> implements A<T?> {}

main() {
  new C();
}