[Bug c++/83624] Strong using deprecation warning in C++03

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83624

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to andysem from comment #0)
> The problem with this warning is that it suggests using inline namespaces
> instead, but that is not an option on C++03 code base. The attribute is used
> precisely to emulate C++11 inline namespaces in C++03 mode.

But GCC supports inline namespaces even in C++03 mode (without
-Wpedantic-errors).

If you can use a non-standard GNU-specific attribute in your C++03 code, then
you should be able to use non-standard inline namespaces in C++03 instead.

i.e. the attribute is deprecated and support for it may eventually be removed,
because you can just use inline namespaces instead. Support for them won't be
removed.