// @dart = 2.9
class A<S> {
  void method<T extends S>(S s) {}
}

class B<S> {
  void method<T extends S>(covariant S s) {}
}

class C<S> extends A<S> implements B<S> {
  void method<T extends S>(S s);
}

class D<S> extends A<S> implements B<S> {}

main() {}