| // 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 We say that a type T0 is a subtype of a type T1 (written T0 <: T1) |
| /// when: |
| /// Left Null: if T0 is Null then: |
| /// - if T1 is a type variable (promoted or not) the query is false |
| /// - If T1 is FutureOr<S> for some S, then the query is true iff Null <: S. |
| /// - If T1 is Null, S? or S* for some S, then the query is true. |
| /// - Otherwise, the query is false |
| /// @description Check that if type T0 is Null and If T1 is S? then T0 is |
| /// subtype of T1 |
| /// @author sgrekhov@unipro.ru |
| |
| |
| class S { |
| const S(); |
| } |
| |
| Null t0Instance = null; |
| S? t1Instance = new S(); |
| |
| const t1Default = const S(); |
| |
| //# @T0 = Null |
| //# @T1 = S? |
