tests/language/void/await_void_error_test.dart

// Copyright (c) 2020, 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.

// Test that it is an error to await an expression of type `void`.

import "dart:async";

void v;
List<void> vs = [null];
FutureOr<void> fov;

void main() async {
  await print('');
  //    ^^^^^
  // [analyzer] COMPILE_TIME_ERROR.USE_OF_VOID_RESULT
  // [cfe] This expression has type 'void' and can't be used.

  await v;
  //    ^
  // [analyzer] COMPILE_TIME_ERROR.USE_OF_VOID_RESULT
  // [cfe] This expression has type 'void' and can't be used.

  await vs[0];
  //    ^^^^^
  // [analyzer] COMPILE_TIME_ERROR.USE_OF_VOID_RESULT
  //      ^
  // [cfe] This expression has type 'void' and can't be used.

  var v2 = vs[0];
  await v2;
  //    ^^
  // [analyzer] COMPILE_TIME_ERROR.USE_OF_VOID_RESULT
  // [cfe] This expression has type 'void' and can't be used.

  // A `FutureOr<void>` can be awaited.
  await fov;
}