// 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 definitions of least and greatest closure are changed in null
 * safe libraries to substitute [Never] in positions where previously [Null
 * would have been substituted, and [Object?] in positions where previously
 * [Object] or [dynamic] would have been substituted.
 * @description Check that correct type is substituted for [void Function<X>()]
 * typedef.
 * @note Read more about the least and greatest closure test template:
 * https://github.com/dart-lang/co19/issues/575#issuecomment-613542349
 *
 * @author iarkh@unipro.ru
 */
// Requirements=nnbd-weak

import "../../../../../Utils/expect.dart";

typedef check = void Function<X>() Function();
typedef expected = void Function<X extends Object?>() Function();

void main() {
  void f(check Function() g) => g();
  Expect.throws(() { f(() => captureTypeArgument()..call()); });
  Expect.equals(expected, capturedTypeArgument);
}