https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68257
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Yes, I was mistaken in my post to the mailing list. It's by design that it uses
the name of the inline namespace as the tag name if no arguments are given,
although I thought the correct syntax in that case was:
inline namespace n __attribute__((__abi_tag__)) {}
i.e. no parentheses after __abi_tag__
