Language/Expressions/If_null_Expressions/syntax_t02.dart

// Copyright (c) 2015, 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
///  ifNullExpression:
///   logicalOrExpression (‘??’ logicalOrExpression)*
///
/// @description Verify several kinds of if-null expressions, logicalOrExpression
/// is a variable.
/// @author a.semenov@unipro.ru

import '../../../Utils/expect.dart';

main() {
  int? x = 1;
  var n = null;

  Expect.equals(1, x ?? 10);
//                      ^^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
  Expect.equals(1, x ?? 10 ?? 20);
//                      ^^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
//                            ^^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
  Expect.equals(1, x ?? 10 ?? 20 ?? 30);
//                      ^^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
//                            ^^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
//                                  ^^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
  Expect.equals(10, n ?? 10);
  Expect.equals(10, n ?? 10 ?? 20);
  Expect.equals(10, n ?? 10 ?? 20 ?? 40);
  Expect.equals(x, x ?? n);
//                      ^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
  Expect.equals(x, n ?? x);
  Expect.equals(x, n ?? n ?? x);
  Expect.equals(x, x ?? n ?? 5);
//                      ^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
  Expect.equals(x, n ?? x ?? 5);
}