// Copyright (c) 2021, 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
/// NORM(FutureOr<T>) =
///  let S be NORM(T)
///  if S is a top type then S
///  if S is Object then S
///  if S is Object* then S
///  if S is Never then Future<Never>
///  if S is Null then Future<Null>?
///  else FutureOr<S>
///
/// @description Checks that if NORM(T) is Null then
/// NORM(FutureOr<T>) = Future<Null>?
///
/// @author sgrekhov@unipro.ru

// Requirements=nnbd-weak
import 'dart:async';

class A<X> {}
class B<X> implements A<X> {}

class C extends B<FutureOr<Null>> implements A<Future<Null>?> {}

main() {
  new C();
}