blob: d4e6e83e0b8b166327fa8b5e64042159eeb106da [file] [log] [blame]
// 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 "more specific" resolving algorithm
/// @author
class A {}
class B {}
class C extends A {}
extension ExtA<T extends A> on List<T> {
String method() => "ExtA method";
extension ExtC<T extends C> on List<T> {
String method() => "ExtC method";
main() {
List<B> list = [new B(), new B()];
// ^
// [analyzer] unspecified
// [cfe] unspecified