// @dart = 2.6
class A {
  bool operator ==(covariant A other) => true;
}

class B extends A {
  bool operator ==(other) => true;
}

class C<T> {
  bool operator ==(covariant C<T> other) => true;
}

class D extends C<int> {}

main() {}
test(A a, B b, C c_dynamic, C<int> c_int, C<String> c_string, D d) {}