// 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 From the Unified collection Spec:
/// A [spreadElement] starting with [...?] is a constant element if its
/// expression is constant and it evaluates to [null] or a constant [List], [Set]
/// or [Map] instance originally created by a list, set or map literal. It is a
/// potentially constant element if the expression is potentially constant
/// expression.
/// @description: Checks that constant map spread [...?] element can only be a
/// constant map or null.
/// @author iarkh@unipro.ru


main() {
  const Map res1 = const {...?{1: 1, 2: 2}, 4: 3};
  const Map res2 = const {...?<Object, Object>{}};
  const Map res3 = const {...?{}};
  const Map res4 = const {...?null};
}