commit ce86d9678b7f3d914133a035fbf8088504d8bad8
author Jonathan Wakely <jwakely@redhat.com> Tue Nov 15 13:44:38 2022 +0000
committer Jonathan Wakely <jwakely@redhat.com> Tue Nov 15 14:01:39 2022 +0000
tree e01701e4c0c82355aa7346e3e2fb48025c1de135
parent 3895318beb8f21965c398c6b89ce6d542bda0aed

libstdc++: Fix detection of std::format support for __float128 [PR107693]

std::format gives linker errors on targets that define __float128 but
do not support using it with std::to_chars. This improves the handling
of 128-bit flaoting-point types so they are disabled if unsupportable.

libstdc++-v3/ChangeLog:

	PR libstdc++/107693
	* include/std/format (_GLIBCXX_FORMAT_F128): Define to 2 when
	basic_format_arg needs to use its _M_f128 member.
	(__extended_floating_point, __floating_point): Replace with ...
	(__formattable_floating_point): New concept.
	* testsuite/std/format/functions/format.cc: Check whether
	__float128 is supported. Also test _Float128.