[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

Peter Dimov <pdimov at gmail dot com> changed:

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                 CC|                            |pdimov at gmail dot com

--- Comment #1 from Peter Dimov <pdimov at gmail dot com> ---
An issue against Boost.System has just been filed as a result of this warning:
https://github.com/boostorg/system/issues/83

It took me a while to figure out why the warning fires: because of the `friend
class error_code` declaration in `error_category`
(https://godbolt.org/z/z6x14P7M4).

Please reconsider issuing the warning when the destructor is protected and a
friend declaration exists. A protected destructor is a clear indication that
the type is intended as a base class.