[Bug libstdc++/101527] The implementation of std::common_iterator::operator== seems to be wrong

[hewillk at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101527

--- Comment #1 from 康桓瑋 <hewillk at gmail dot com> ---
(In reply to 康桓瑋 from comment #0)
> But according to the description of [class.friend#10]: "Friendship is
> neither inherited nor transitive." this will cause the following valid codes
> to be rejected:

This is the implementation divergence of CWG1699.