pkg/front_end/testcases/general/issue51815/main_lib.dart

// Copyright (c) 2023, 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<X> {}

class B extends A<(int, String)> {
  void call() {}
}