[PATCH] Fix inline versioned namespace bootstrap

[Jonathan Wakely]

On Fri, 27 Aug 2021 at 21:58, François Dumont via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> Since std::allocator<void> is not specialized anymore in
> _GLIBCXX_INLINE_VERSION mode _ExtPtr_allocator<void> specialization do
> not compile
>
> because std::allocator<void> is incomplete.

That doesn't look right ... it should be complete. This suggests there
is a deeper problem, which I'll look into.



>
> So I think primary _ExtPtr_allocator template should also be prefered in
> _GLIBCXX_INLINE_VERSION mode.

I think it should always be preferred. The _ExtPtr_allocator<void>
specialization is useless, it is missing the converting constructor
that would be needed to convert to/from that type to any other
_ExtPtr_allocator<T> specialization.