LanguageFeatures/Control-flow-collections/const_collections_A02_t02.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 An entry element (the base case in maps):
///
/// It is a compile-time error if the key and value expressions are not constant
/// expressions.
///
/// As is already the case in Dart, it is a compile-time error if the key is an
/// instance of a class that implements the operator == unless the key is a
/// Boolean, string, an integer, a literal symbol or the result of invoking a
/// constant constructor of class Symbol. It is a compile-time error if the type
/// arguments of a constant map literal include a type parameter.
///
/// The expansion is the entry formed by the key and value expression values.
///
/// @description Checks that it is a compile-time error if the key is an
/// instance of a class that implements the operator ==
/// @author sgrekhov@unipro.ru


class C {
  final int id;
  final String name;
  const C(this.id, this.name);
  int get hashCode => id;
  bool operator==(Object other) => other is C && id == other.id;
  String toString() => "C($id, $name)";
}

main() {
  var v1 = const {if (true) const Duration(seconds: 1): 1};
  //  ^
  // [cfe] Constant evaluation error:
  //                        ^^^^^^^^^^^^^^^^^^^^^^^^^^
  // [analyzer] COMPILE_TIME_ERROR.CONST_MAP_KEY_EXPRESSION_TYPE_IMPLEMENTS_EQUALS
  var v2 = const <Object?, String?> {if (1 > 0) const Duration(seconds: 1), "x"};
//                                              ^^^^^^^^^^^^^^^^^^^^^^^^^^
// [analyzer] unspecified
// [cfe] unspecified
  var v3 = const {if (2 > 0) const C(1, "x"): "c"};
  //  ^
  // [cfe] Constant evaluation error:
  //                         ^^^^^^^^^^^^^^^
  // [analyzer] COMPILE_TIME_ERROR.CONST_MAP_KEY_EXPRESSION_TYPE_IMPLEMENTS_EQUALS
  const v4 = {if (2 > 0) const C(1, "x"): "c"};
  //    ^
  // [cfe] Constant evaluation error:
  //                     ^^^^^^^^^^^^^^^
  // [analyzer] COMPILE_TIME_ERROR.CONST_MAP_KEY_EXPRESSION_TYPE_IMPLEMENTS_EQUALS
}