[Bug c++/106652] [C++23] P1467 - Extended floating-point types and standard names

["joseph at codesourcery dot com" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106652

--- Comment #4 from joseph at codesourcery dot com <joseph at codesourcery dot com> ---
Regarding mangling: I expect this change should fix bug 85518.

General: I expect some glibc header changes might be appropriate, where 
they currently assume __FloatN keywords aren't supported in C++.  And 
where glibc headers handle type-generic operations for C++ by defining 
appropriate overloaded functions in the headers, make sure the overloads 
for _Float128 work with both _Float128 and __float128 where supported and 
distinct, or otherwise adjust the headers as needed to handle both types.

(Also, so far we don't have _Float16 support in glibc, and while it would 
be a sensible feature in principle, there would be issues to consider with 
the impact on minimum GCC versions for building glibc on relevant 
architectures, unless some kind of hack is used to allow _Float16 
functions to be built and to get the correct ABI even when built with an 
older compiler.  Requiring GCC 7 to build glibc for AArch64 and Arm might 
well be reasonable now; requiring GCC 12 for x86/x86_64 or GCC 13 for 
RISC-V probably not for a few years.)