[Bug c++/102168] -Wnon-virtual-dtor shouldn't fire for protected dtor in a class with a friend declaration

[pdimov at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102168

--- Comment #6 from Peter Dimov <pdimov at gmail dot com> ---
Yes, I suppose you're right. The warning warns that Derived _can be_ deleted
via Base*, and that's correct - if not very useful in practice in this specific
case.

In fact the private destructor case is even less useful. ~Derived won't compile
unless it's Derived that is Base's friend, in which case everything is actually
fine.

I suppose we'll have to live with it. The annoying part is that there's no
warning, and then you add an unrelated friend declaration while refactoring,
and the warning appears.