/*
 * Copyright (c) 2019, 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 grammar of types is extended to allow any type to be suffixed
 * with a ? (e.g. int?) indicating the nullable version of that type.
 *
 * @description Check that any type can be suffixed with a ? indicating the
 * nullable version of that type. Test function types
 * @author sgrekhov@unipro.ru
 */
// Requirements=nnbd-strong
typedef void foo();

foo? bar(foo? v) => v;

main() {
  foo? f = null;
  f = bar(f);
}