https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94454
--- Comment #10 from Nathan Sidwell <nathan at gcc dot gnu.org> ---
I cannot reproduce it, but looking at the gist referenced in comment #1 I see
that the complaint is about two instances of the same instantiation of struct
std::integral_constant<bool, and_v<__is_constructible(Ts)...> >
One of which has __attribute__ ((__abi_tag__ ("cxx11"))) attached to it. That
seems to be the error -- how did that abi_tag get there? it's not on the
original declaration.
I can't see how those could have become attached. AFAICT we don't propagate
attributes from the arguments of an instantiation, to the instantiation itself
(and that wouldn't explain it here, as 'and_v' and __is_constructible are
unattributed.
