| // 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 type |
| * dynamically for `bool` type parameter and the expression can be `null` in |
| * weak mode. |
| * |
| * Here is a situation where sound and non-sound null checking produce different |
| * results. The `null` value is a result of `getNull()`, it's tested using `null |
| * as bool`, and such a cast succeeds. So `test()` does not throw error and |
| * returns `Future<bool>` that will be completed with `null`. No dynamic error |
| * here. |
| * |
| * @Issue https://github.com/dart-lang/language/pull/941 |
| * @Issue https://github.com/dart-lang/co19/issues/703 |
| * @Issue 41266,41437,42236,42237 |
| * @author iarkh@unipro.ru |
| */ |
| // Requirements=nnbd-weak |
| |
| import "dart:async"; |
| import "../../../Utils/expect.dart"; |
| |
| dynamic getNull() => null; |
| |
| Future<bool> test() async => await getNull(); |
| |
| main() { |
| asyncStart(); |
| test().then((value) => asyncEnd()); |
| } |