tests/language/extension_methods/static_extension_resolution_failures_test.dart

// 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.

// Tests extension method resolution failures.

import "package:expect/expect.dart";

main() {
  A a = C();
  B1 b1 = C();
  B2 b2 = C();
  C c = C();

  Expect.equals("EA.v1", a.v1);
  Expect.equals("EB1.v1", b1.v1);
  Expect.equals("EB2.v1", b2.v1);
  Expect.equals("EC.v1", c.v1);

  Expect.equals("EA.v2", a.v2);
  Expect.equals("EB1.v2", b1.v2);
  Expect.equals("EB2.v2", b2.v2);
  // Cannot determine which of EB1 and EB2's v2 is more specific
  c.v2;
  //^^
  // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
  // [cfe] The property 'v2' is defined in multiple extensions for 'C' and neither is more specific.

  Expect.equals("EA.v3", a.v3);
  Expect.equals("EA.v3", b1.v3);
  Expect.equals("EA.v3", b2.v3);
  Expect.equals("EA.v3", c.v3);

  Iterable<num> i_num = <int>[];
  Iterable<int> ii = <int>[];
  List<num> ln = <int>[];
  List<int> li = <int>[];

  // No `i_num` extension declared.
  i_num.i_num;
  //    ^^^^^
  // [analyzer] COMPILE_TIME_ERROR.UNDEFINED_GETTER
  // [cfe] The getter 'i_num' isn't defined for the class 'Iterable<num>'.

  Expect.equals("Iterable<int>.i_num", ii.i_num);
  Expect.equals("List<num>.i_num", ln.i_num);

  // Both apply, neither is more specific.
  li.i_num;
  // ^^^^^
  // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
  // [cfe] The property 'i_num' is defined in multiple extensions for 'List<int>' and neither is more specific.

  // no most specific because both are equally specific.
  c.cs;
  //^^
  // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
  // [cfe] The property 'cs' is defined in multiple extensions for 'C' and neither is more specific.

  // Both EIT.e1 and ELO.e1 apply, but their instantiated on
  // types are incomparable, and hence this is an error.
  ln.e1();
  // ^^
  // [analyzer] COMPILE_TIME_ERROR.AMBIGUOUS_EXTENSION_MEMBER_ACCESS
  // [cfe] The method 'e1' is defined in multiple extensions for 'List<num>' and neither is more specific.
}

// Diamond class hierarchy.
class A {}

class B1 implements A {}

class B2 implements A {}

class C implements B1, B2 {}

extension EA on A {
  String get v1 => "EA.v1";
  String get v2 => "EA.v2";
  String get v3 => "EA.v3";
}

extension EB1 on B1 {
  String get v1 => "EB1.v1";
  String get v2 => "EB1.v2";
}

extension EB2 on B2 {
  String get v1 => "EB2.v1";
  String get v2 => "EB2.v2";
}

extension EC on C {
  String get v1 => "EC.v1";
}

// Iterable<num>, Iterable<int>, List<num> and List<int> also forms diamond
// hierarchy.
extension II on Iterable<int> {
  String get i_num => "Iterable<int>.i_num";
}

extension LN on List<num> {
  String get i_num => "List<num>.i_num";
}

// Two exactly identical `on` types.
extension C1 on C {
  String get cs => "C1.cs";
}

extension C2 on C {
  String get cs => "C2.cs";
}

extension EIT<T> on Iterable<T> {
  String e1() => "Iterable<T>.e1";
}

extension ELO on List<Object> {
  String e1() => "List<Object>.e1";
}