| // Copyright (c) 2016, 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 Evaluation of a compound assignment of the form e1?.v ??= e2 is |
| /// equivalent to the evaluation of the expression |
| /// ((x) => x == null ? null: x.v?? = e2)(e1) where x is a variable that is not |
| /// used in e2. |
| /// @description Checks that in expression of the form e1?.v ??= e value is set |
| /// only if e1.v == null and returns null if e1 == null |
| /// @author sgrekhov@unipro.ru |
| |
| |
| import '../../../../Utils/expect.dart'; |
| |
| class C { |
| var v = null; |
| } |
| |
| main() { |
| C? c = null; |
| var res = (c?.v ??= 1); |
| Expect.isNull(res); |
| Expect.isNull(c); |
| |
| c = new C(); |
| res = (c?.v ??= 2); |
| // ^^ |
| // [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR |
| // ^ |
| // [cfe] Operand of null-aware operation '?.' has type 'C' which excludes null. |
| Expect.equals(2, res); |
| Expect.equals(2, c.v); |
| |
| res = (c?.v ??= 3); |
| // ^^ |
| // [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR |
| // ^ |
| // [cfe] Operand of null-aware operation '?.' has type 'C' which excludes null. |
| Expect.equals(2, res); |
| Expect.equals(2, c.v); |
| } |