| // Copyright (c) 2019, 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 If more than one extension applies to a specific member |
| /// invocation, then we resort to a heuristic to choose one of the extensions to |
| /// apply. If exactly one of them is "more specific" than all the others, that |
| /// one is chosen. Otherwise it is a compile-time error. |
| /// |
| /// An extension with [on] type clause [T1] is more specific than another |
| /// extension with [on] type clause [T2] iff |
| /// |
| /// 1. The latter extension is declared in a platform library, and the former |
| /// extension is not |
| /// 2. they are both declared in platform libraries or both declared in |
| /// non-platform libraries, and |
| /// 3. the instantiated type (the type after applying type inference from the |
| /// receiver) of [T1] is a subtype of the instantiated type of [T2] and |
| /// either |
| /// 4. not vice versa, or |
| /// 5. the instantiate-to-bounds type of [T1] is a subtype of the |
| /// instantiate-to-bounds type of [T2] and not vice versa. |
| /// |
| /// @description Check that it is a compile error if there is no most specific |
| /// extension |
| /// @author sgrekhov@unipro.ru |
| |
| |
| |
| extension SmartIterable on Iterable<int> { |
| void checkme() {} |
| } |
| |
| extension SmartList on List<num> { |
| int checkme() => 0; |
| } |
| |
| main() { |
| List<int> x = [3, 1, 4]; |
| x.checkme(); |
| // ^ |
| // [analyzer] unspecified |
| // [cfe] unspecified |
| } |