// Copyright (c) 2017, 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.

/*@testedFeatures=inference*/
library test;

import 'dart:async';

main() async {
  var /*@type=() -> Stream<Null>*/ f = /*@returnType=Stream<Null>*/ () async* {
    yield null;
  };
  Stream y = f();
  Stream<String?> z = f();
  String? s = await f(). /*@target=Stream.first*/ first;
}