I'd call it: Mutual dependency on implementation rather than interface. Use of C++'s friend is worse: https://en.cppreference.com/w/cpp/language/friend https:/

I'd call it: Mutual dependency on implementation rather than interface. Use of C++'s friend is worse: https://en.cppreference.com/w/cpp/language/friend https://en.cppreference.com/w/cpp/language/friend