blob: 516f7e3789656b85c189646c891c40190dac0645 [file] [log] [blame]
// 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 `int` 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 int`, and such a cast succeeds. So `test()` does not throw error and
/// returns `Future<int>` that will be completed with `null`. No dynamic error
/// here.
/// @author
// Requirements=nnbd-weak
import "dart:async";
import "../../../Utils/expect.dart";
dynamic getNull() => null;
Future<int> test() async {
int i = await getNull();
return i;
main() {
test().then((value) => asyncEnd());