// 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 It is a warning to use a null aware operator (?., ?.., ??, ??=,
/// or ...?) on an expression of type T if T is strictly non-nullable.
///
/// @description Check it is a warning to use a null aware operator (?., ?.., ??,
/// ??=, or ...?) on a strictly non-nullable receiver. Test Function type
/// @author sgrekhov@unipro.ru
/// @issue 39598
/// @issue 39714

void foo() {}
void bar() {}

main() {
  Function a = foo;
  a?.toString();
// ^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
  a?..toString();
// ^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
  a ?? bar;
//     ^^^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
  a ??= bar;
//      ^^^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
  List<Function> clist = [foo, bar];
  List<Function> alist = [foo, bar, ...? clist];
//                                  ^^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
}