Re: Using glibc headers with non-GCC compilers which define _Float32 etc.

[Florian Weimer <fweimer@redhat.com>]

* Andreas Schwab:

> On Apr 03 2023, Florian Weimer via Libc-alpha wrote:
>
>> We have a downstream bug that points out that if __GNUC__ is not
>> defined, glibc assumes that it's necessary to define _Float32 as a
>> typedef to float:
>>
>>   glibc: _FloatN and _FloatNx problem if _GNUC__ is not defined
>>   <https://bugzilla.redhat.com/show_bug.cgi?id=2183212>
>>
>> That does not work if the compiler already defines _Float32.
>>
>> What should we do about this?
>
> I don't think we should support that use case.  It's probably not the
> only thing that will break in this situation.

The -U__GNUC__ option is just a shortcut for reproduction.  I think the
fundamental issue is that our headers do not work if the compiler does
not define __GNUC__, but predefines types like _Float32.  I think our
goal is to support non-GCC compilers, so this seems to be fairly broken.
It also blocks defining _Float32 et al. in Clang.

Thanks,
Florian