Re: [PATCH] Fix gnu-versioned-namespace build

[Jonathan Wakely <jwakely@redhat.com>]

On 30/10/20 13:59 +0100, François Dumont via Libstdc++ wrote:
>The gnu-versioned-namespace build is broken.
>
>The fix in charconv/floating_from_chars.cc is quite trivial. I am not 
>so sure about the fix in sstream-inst.cc.

The change for src/c++20/sstream-inst.cc is OK to commit. It would
probably be better to not build that file at all if the cxx11 ABI is
not supported at all, but then the src/c++20 directory would be empty
and I'm not sure if that would work. So just making the file empty is
fine.

The change for from_chars is not OK. With your change the <charconv>
header doesn't declare those functions if included by a file using the
old ABI. That's wrong, they should be declared unconditionally.

I see two ways to fix it. Either make the declarations in the header
depend on ! _GLIBCXX_INLINE_VERSION (so they're disabled for
gnu-versioned namespace) or fix the code in floating_from_chars to not
use a pmr::memory_resource for allocation in the versioned namespace
build.

Please commit the sstream-inst.cc part only, thanks.