| // 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: |
| /// Right Nullable: if T1 is S1? then: |
| /// T0 <: T1 iff any of the following hold: |
| /// either T0 <: S1 |
| /// or T0 <: Null |
| /// or T0 is X0 and X0 has bound S0 and S0 <: T1 |
| /// or T0 is X0 & S0 and S0 <: T1 |
| /// @description Check that if type T1 is S1? and T0 is Null then T0 is subtype |
| /// of T1. |
| /// @author sgrekhov@unipro.ru |
| |
| |
| class S1 { |
| const S1(); |
| } |
| |
| Null t0Instance = null; |
| S1? t1Instance = new S1(); |
| |
| const t1Default = const S1(); |
| |
| //# @T0 = Null |
| //# @T1 = S1? |
