LanguageFeatures/Private-fields-promotion/promotion_A04_t01.dart

// Copyright (c) 2022, 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 An instance field is promotable if all the following conditions
/// hold:
/// - It refers to a field (not a getter)
/// - The field is private
/// - The field is final
/// - There is no getter with the same name elsewhere in the library
/// - There is no non-final field with the same name elsewhere in the library
/// - There is no implicit noSuchMethod forwarder with the same name elsewhere
///   in the library.
///
/// @description Checks that if there are other concrete class instance getters
/// with the same name in the same library and they are not a final fields then
/// the field is not promotable. Test the case when there is a getter with the
/// same name in some extension in the same library. In this case promotion is
/// allowed
/// @author sgrekhov22@gmail.com

class A {}

class C<T> {
  final T _x;
  C(this._x);

  void testC() {
    if (_x is int) {
      _x.isOdd;
    }
  }
}

extension on A {
  String get _x => "Lily was here";
}

extension on C {
  int get _x => 42;
}

main() {
  C<num?> c = C(43);
  if (c._x is int) {
    c._x.isEven;
  }
  c.testC();
  A()._x; // to remove `not used` hint
}