LanguageFeatures/nnbd/type-normalization/equations_A11_t02.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.

/// @assertion The NORM relation defines the canonical representative of classes
/// of equivalent types...
/// This is based on the following equations:
///   FutureOr<T> == T if Future<T> <: T
///
/// @description Checks that if Future<T> is not subtype of T then
/// FutureOr<T> != T
///
/// @author sgrekhov@unipro.ru


import 'dart:async';

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

  class CT extends B<FutureOr<T>> implements A<T> {}
//      ^^
// [analyzer] unspecified
// [cfe] unspecified
  class CN extends B<FutureOr<Null>> implements A<Null> {}
//      ^^
// [analyzer] unspecified
// [cfe] unspecified
  class CF extends B<FutureOr<Future>> implements A<Future> {}
//      ^^
// [analyzer] unspecified
// [cfe] unspecified

main() {
  new CT();
  new CN();
  new CF();
}