On Tue, Dec 06, 2022 at 08:56:09AM -0600, Segher Boessenkool wrote:
> > In the past, _Float128 was a C extended type,
> > but now it is a part of the C/C++ 2x standards.
>
> Only if you select a new enough -std=, it still is an extended type if
> not?
No, as an extension _Float{16,32,64,128}{,x} are available (where the backend
has support for such IEEE format) even in older C or C++ modes,
similarly the {f,F}{16,32,64,128} suffixes on literals (with pedwarn
on everything but C++23). In C++ it is in all language modes treated as
distinct type from __float128, and _FloatNN is handled as extended floating
point type per C++23 rules, while __float128 is not.
Though, the libstdc++ support for the new extended floating point types
is mostly enabled only for C++23 (one exception is std::format).
Jakub
