LanguageFeatures/Spread-collections/TypeInference_A03_t03.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.

/// @assertion If a map literal has a downwards inference type of [Map<K, V>] for
/// some [K] and [V], then the downwards inference context type of a spread
/// element in that map is [Map<K, V>].
/// @description Checks statically that a spread element inference context type
/// is [K, V] in the map literal
/// @author iarkh@unipro.ru


class A1 {}
class B1 extends A1 {}
class C1 extends B1 {}

class A2 {}
class B2 extends A2 {}
class C2 extends B2 {}

Map<K, V> getAMap<K, V>(var a, var b) { return <K, V>{a: b}; }

main() {
  var int_map = getAMap<int, int>(1, 2);
  var str_map = getAMap<int, String>(1, "test");

  var a_map = getAMap<A1, A2>(new A1(), new A2());
  var b_map = getAMap<B1, B2>(new B1(), new B2());
  var c_map = getAMap<C1, C2>(new C1(), new C2());

  Map map1 = <int, int>{...str_map};
  //                       ^^^^^^^
  // [analyzer] COMPILE_TIME_ERROR.MAP_VALUE_TYPE_NOT_ASSIGNABLE
  // [cfe] Can't assign spread entry values of type 'String' to map entry values of type 'int'.
  Map map2 = <int, String>{1: "1", 2: "2", ...int_map, 14: "14"};
  //                                          ^^^^^^^
  // [analyzer] COMPILE_TIME_ERROR.MAP_VALUE_TYPE_NOT_ASSIGNABLE
  // [cfe] Can't assign spread entry values of type 'int' to map entry values of type 'String'.
  Map map3 = <int, C2>{1 : new C2(), ...c_map};
  //                                    ^^^^^
  // [analyzer] COMPILE_TIME_ERROR.MAP_KEY_TYPE_NOT_ASSIGNABLE
  // [cfe] Can't assign spread entry keys of type 'C1' to map entry keys of type 'int'.
  Map map4 = <int, A2>{...int_map};
  //                      ^^^^^^^
  // [analyzer] COMPILE_TIME_ERROR.MAP_VALUE_TYPE_NOT_ASSIGNABLE
  // [cfe] Can't assign spread entry values of type 'int' to map entry values of type 'A2'.
  Map map5 = <A1, String>{...?str_map};
//                            ^^^^^^^
// [analyzer] unspecified
// [cfe] unspecified
}