/*
 * Copyright (c) 2023-2024 Huawei Device Co., Ltd.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

let b : Int = 10;

function foo(): Int {
  b = 11;
  return 12;
}

function main() : void {
  let a : Int = 1;
  let c = a ?? foo();
  assert(b == 10);
  assert(c == 1);

  a = null;
  c = a ?? b;
  assert (c == 10);

  c = a ?? foo();
  assert (b == 11);
  assert (c == 12);

  let d : Boolean = true;
  let e : boolean = false;
  let f = d ?? e;
  assert (f == true);
}