On Tue, 17 Sept 2024 at 13:52, Inbal Levi <sinbal2l_at_[hidden]> wrote:

> Hello SG10,
> We're in the process of rebasing C++ on C (we will see a paper today) and
> wanted your input on what to do with the C macros:
> https://en.cppreference.com/w/c/23
> (e.g __STDC_VERSION_STDCKDINT_H__
> <https://en.cppreference.com/mwiki/index.php?title=STDC_VERSION_STDCKDINT_H&action=edit&redlink=1>
> , __STDC_VERSION_FENV_H__ <https://en.cppreference.com/w/c/numeric/fenv> might
> be relevant)
>
> IIUC, we don't port these?
>

It's never been a question before, C17 didn't have any such macros. They're
new in C23.



>
> https://gcc.gnu.org/onlinedocs/cpp/Standard-Predefined-Macros.html#Standard-Predefined-Macros-1
>

I don't think that document is relevant, those macros are defined by
library headers not the compiler.


>
> Should we consider redefining them in the __cplusplus shape?
>

The macro for <fenv.h> comes from a C header, and the C++ library doesn't
add anything to that header. I don't see any point in the C++ library
requiring new macros for a header that isn't controlled by the C++
implementation. We also haven't got a decision on what to do with the new
math and numerics stuff in C23.

For stdckdint.h we're not going to use the C header, so should not define
the C macro. The proposal to add a C++ version of that header should
consider whether a feature test macro is needed. If it is, it should be in
the __cpp_lib_xxx form.