LanguageFeatures/Spread-collections/TypeInference_A01_t05.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 list or set literal has a downwards inference type of
/// [Iterable<T>] for some [T], then the downwards inference context type of a
/// spread element in that list is [Iterable<T>].
/// @description Checks statically that a spread element inference context type
/// is [T] in the set literal
/// @author iarkh@unipro.ru


class A {}
class B extends A {}
class C extends B {}

List<T> getAList<T>(var a) { return <T>[a]; }

main() {
  var a_list   = getAList<A>(new A());
  var b_list   = getAList<B>(new B());
  var c_list   = getAList<C>(new C());
  var int_list = getAList<int>(12);
  var str_list = ["string"];
  A a = new A();
  B b = new B();
  C c = new C();

  Set set1 = <int>{2, 7, ...int_list, 4};
  Set set2 = <A>{a, ...a_list};
  Set set3 = <A>{a, ...b_list};
  Set set4 = <A>{a, c, ...c_list, b};
  Set set5 = <A>{a, b, c, ...c_list, new B(), ...a_list, ...b_list, new A()};
  Set set6 = <B>{b, ...b_list, c, ...c_list};
  Set set7 = {123, "123", null, a, ...a_list, ...?b_list, c, b, ...?c_list,
//                                            ^^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
//                                                ^
// [cfe] Operand of null-aware operation '...?' has type 'List<B>' which excludes null.
//                                                              ^^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
//                                                                  ^
// [cfe] Operand of null-aware operation '...?' has type 'List<C>' which excludes null.
      ...str_list, ...int_list, null, 1499, []};
}