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

[pinskia at gcc dot gnu.org via Gcc-bugs]

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

--- Comment #9 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
There does seems some inconsitency though:
inline namespace n __attribute__((__abi_tag__(""))) {}
is rejected but
inline namespace n __attribute__((__abi_tag__())) {}

Is not.