// 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 For the purposes of errors and warnings, the null aware operators
/// ?., ?.., and ?[] are checked as if the receiver of the operator had
/// non-nullable type. More specifically, if the type of the receiver of a null
/// aware operator is T, then the operator is checked as if the receiver had type
/// NonNull(T).
///
/// @description Check that it is no error if receiver has nullable type. Test
/// type alias
/// @author sgrekhov@unipro.ru

// Requirements=nnbd-strong
class A {
  void test() {}
  int operator[](int index) => 0;
}

typedef AAlias = A?;

main() {
  AAlias a = null;
  a?.test();
  a ?.. test();
  a?[0];
}