LanguageFeatures/nnbd/future_flattening_A01_t32.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 flatten function is modified as follows:
 *
 * [flatten(T)] is defined by cases on [T]:
 *
 *   if [T] is [S?] then [flatten(T) = flatten(S)?]
 *   otherwise if [T] is [S*] then [flatten(T) = flatten(S)*]
 *   otherwise if [T] is [FutureOr<S>] then [flatten(T) = S]
 *   otherwise [if T <: Future] then let [S] be a type such that [T <:
 *       Future<S>] and for all [R], if [T <: Future<R>] then [S <: R]; then
 *       [flatten(T) = S]
 *   otherwise [flatten(T) = T]
 *
 * @description Check that type of await expression match with expected
 * non-nullable [FutureOr] statically and the expression cannot be null.
 *
 * @author iarkh@unipro.ru
 */

import "dart:async";

Future<FutureOr<bool>> test() async {
  FutureOr<bool> b = await null;
//                   ^
// [analyzer] unspecified
// [cfe] unspecified

  FutureOr<int> i = await null;
//                  ^
// [analyzer] unspecified
// [cfe] unspecified

  FutureOr<String> s = await null;
//                     ^
// [analyzer] unspecified
// [cfe] unspecified

  FutureOr<Object> o = await null;
//                     ^
// [analyzer] unspecified
// [cfe] unspecified

  return null;
//       ^
// [analyzer] unspecified
// [cfe] unspecified
}

main() {}