| // 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 Since the spread is unpacked and its individual elements added to |
| /// the containing collection, we don't require the spread expression itself to |
| /// be assignable to the collection's type. For example, this is allowed: |
| /// |
| /// var numbers = <num>[1, 2, 3]; |
| /// var ints = <int>[...numbers]; |
| /// |
| /// This works because the individual elements in numbers do happen to have the |
| /// right type even though the list that contains them does not. As long as the |
| /// spread object is "spreadable" — it implements [Iterable] — there is no |
| /// static error. |
| /// @note That's an error with null-safety to assign Map<num, num> to |
| /// Map<int, int>, see |
| /// https://github.com/dart-lang/language/blob/471a98ca0dd5b02d194ffad0dc128065771253a0/specification/dartLangSpec.tex#L8245, |
| /// because `num` isn't assignable to `int`. |
| /// @description Checks that it's possible to have the spread expression which is |
| /// not assignable to the collection type for the map. |
| /// @author iarkh@unipro.ru |
| |
| |
| import "../../Utils/expect.dart"; |
| |
| main() { |
| Map numbers = <num, num>{1: 1, 2: 2, 3: 3}; |
| Expect.mapEquals({1: 1, 2: 2, 3: 3}, <int, int>{...numbers}); |
| |
| Map objects = <Object, Object>{2: 22, 7: 77, 9: 99}; |
| Expect.mapEquals({2: 22, 7: 77, 9: 99}, <int, int>{...objects}); |
| |
| var a; |
| Expect.throws(() => a = <String, int>{...objects}); |
| |
| Map strings = <String, String>{}; |
| Expect.mapEquals({}, <int, int>{...strings}); |
| |
| var numbers1 = {1: 1, 2: 2, 3: 3} as Map?; |
| Expect.mapEquals({1: 1, 2: 2, 3: 3}, <int, int>{...?numbers1}); |
| |
| var objects1 = <Object, Object>{2: 22, 7: 77, 9: 99} as Map?; |
| Expect.mapEquals({2: 22, 7: 77, 9: 99}, <int, int>{...?objects1}); |
| |
| Expect.throws(() => a = <String, int>{...?objects1}); |
| |
| var strings1 = <String, String>{} as Map?; |
| a = <int, int>{11: 12, ...?strings1}; |
| } |