LanguageFeatures/Spread-collections/Syntax_A02_t07.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.

// @dart = 2.9

/// @assertion The grammar changes for map and set are a little more complex
/// because of the potential ambiguity of collections containing only spreads.
/// The changed and new rules are:
///
///    setOrMapLiteral:
///    mapLiteral |
///    setLiteral |
///    mapOrSetLiteral
///    ;
///
///    mapLiteral:
///    const? typeArguments? '{' mapLiteralEntryList? '}'
///    ;
///
///    mapLiteralEntryList:
///    mapLiteralEntry ( ',' mapLiteralEntry )* ','?
///    ;
///
///    mapLiteralEntry:
///    expression ':' expression |
///    spread
///    ;
///
///    setLiteral:
///    'const'? typeArguments? '{' spreadableList '}' ;
///
///    mapOrSetLiteral:
///    'const'?  '{' spread (',' spread)* '}' ;
///
/// @description Checks that spreadable map can not be declared as constant if
/// spreadable element is not a constant.
/// @author iarkh@unipro.ru


main() {
  Map map1 = {1: 1, 2: 4, 3: 6};
  Map map2;
  int i;

  Map a;
  a = const {...map2};          //# 01: compile-time error
  a = const {...map1, ...map2}; //# 02: compile-time error
  a = const {...map2, ...map1}; //# 03: compile-time error

  a = const {...map2, 10: 2};   //# 04: compile-time error
  a = const {10: 2, ...map2};   //# 05: compile-time error

  a = const {...map1, i: 10};   //# 06: compile-time error
  a = const {...map1, 10: i};   //# 07: compile-time error
  a = const {i: 10, ...map1};   //# 08: compile-time error
  a = const {10: i, map1};      //# 09: compile-time error
}