| /* |
| * 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 assignment of an |
| * expression of 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 T <: S and not S <: T |
| * and T is a type of interest for x in tested |
| * |
| * @description Checks that a variable is promotable to the type T if all |
| * requirements above are met. |
| * |
| * @author sgrekhov@unipro.ru |
| */ |
| // Requirements=nnbd-strong |
| |
| class S {} |
| class T extends S { |
| int foo() => 42; |
| } |
| |
| main() { |
| S x = new S(); |
| if (x is T) { |
| // nothing |
| } |
| x = new T(); |
| x.foo(); |
| } |
