// Copyright (c) 2016, 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.md file.
// @dart=2.9
typedef void Foo();

main() {
  print(Foo);
  Foo = null;
  Foo ??= null;
  Foo();
}