| // 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 variable x is promotable via type test with type T |
| /// given variable model VM if |
| /// |
| /// VM = VariableModel(declared, promoted, tested, assigned, unassigned, captured) |
| /// and captured is false |
| /// and S is the current type of x in VM |
| /// and not S <: T |
| /// and T <: S or (S is X extends R and T <: R) or (S is X & R and T <: R) |
| /// |
| /// @description Checks that a variable is promotable to the type T if all |
| /// requirements above are met. Test T <: S |
| /// |
| /// @author sgrekhov@unipro.ru |
| |
| // Requirements=nnbd-strong |
| |
| class S {} |
| class T extends S { |
| int foo() => 42; |
| } |
| |
| main() { |
| S x = new T(); |
| if (x is T) { |
| x.foo(); |
| } |
| } |
