[Bug c++/68257] Reject empty abi_tag attribute on inline namespace

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68257

--- Comment #5 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Stephan Bergmann from comment #4)
> Created attachment 36973 [details]
> proposed documentation patch

is used as <ins>the</ins> ABI tag

?