LanguageFeatures/nnbd/Least-greatest-closure/typedef/typedef_dynamic_t22.dart

/*
 * Copyright (c) 2020, 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 [typedef check<X> =
 * void Function(X x)].
 * @note Read more about the least and greatest closure test template:
 * https://github.com/dart-lang/co19/issues/575#issuecomment-613542349
 *
 * @Issue 44163, 44164
 * @author iarkh@unipro.ru
 */
// Requirements=nnbd-strong

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

typedef check<X> = X Function(X x);
typedef expected = Object Function(Never x);

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