[Bug c++/84782] Rejects a maybe C++ code snippet

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84782

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Slight correction: the using-declaration doesn't have no effect in general, but
it shouldn't change the result of this program.