LanguageFeatures/nnbd/nullability_definitions_A02_t04.dart

// 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 We say that a type T is non-nullable if T <: Object. This is
/// equivalent to the syntactic criterion that T is any of:
///  Never
///  Any function type (including Function)
///  Any interface type except Null.
///  S* for some S where S is non-nullable
///  FutureOr<S> where S is non-nullable
///  X extends S where S is non-nullable
///  X & S where S is non-nullable
///
/// @description Check that type which is not subtype of Object cannot be
/// assigned to non-nullable type. Test interface type. Test type aliases
/// @author sgrekhov@unipro.ru

abstract class A {
  void foo(int i);
}

class C {
  int bar(int i) => i;
}

typedef AAlias = A;
typedef CAlias = C;

main() {
  AAlias a1 = null;
//            ^^^^
// [analyzer] unspecified
// [cfe] unspecified

  CAlias c1 = null;
//            ^^^^
// [analyzer] unspecified
// [cfe] unspecified

  AAlias? a = null;
  AAlias a2 = a;
//            ^
// [analyzer] unspecified
// [cfe] unspecified

  var c = new C() as CAlias?;
  CAlias c2 = c;
//            ^
// [analyzer] unspecified
// [cfe] unspecified
}