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Message-ID: <20230524161101.785c148f@inria.fr>
Date: Wed, 24 May 2023 16:11:01 +0200
From: Jₑₙₛ Gustedt <jens.gustedt@...ia.fr>
To: Rich Felker <dalias@...c.org>
Cc: musl@...ts.openwall.com
Subject: Re: [C23 feature tests 0/6] tests needed for C23 interfaces
Rich,
on Wed, 24 May 2023 09:58:37 -0400 you (Rich Felker <dalias@...c.org>)
wrote:
> On Wed, May 24, 2023 at 12:04:34PM +0200, Jens Gustedt wrote:
> > C23 has some new features, in particular attributes, that are
> > prescribed for certain headers.
> >
> > Jens Gustedt (6):
> > C23: provide fallbacks for the use of C attributes
> > C23: add a feature test for the __VA_OPT__ feature
> > C23: add a feature test for the [u]int128_t
> > Add a feature test for the _BitInt types.
> > add a `__inline_or_static` macro for pre-C99 compilers
> > C23: add an internal interface for the new unsequenced attribute
> >
> > include/features.h | 51
> > +++++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 50
> > insertions(+), 1 deletion(-)
> >
> > --
> > 2.34.1
>
> I don't see a motivation for any of the patches in this series.
sure, you don't have the usage side yet, please be patient
I decided to group them together, because they are the easiest applied
at the beginning.
> For the ones which test for compiler features, musl does not use any
> of these features internally, so it does not have any use for
> testing for their support.
> At the public header level, they're only to be used in
> things which are C23-only, and can just be used unconditionally in the
> C23-only macros that need them.
These are not macros that need them, but functions. C23 requires
changes from `_Noreturn` to `[[noreturn]]` for example, deprecates
functions and stuff like that.
> For __noreturn, we already have _Noreturn (just above your new
> definition in the patch). I'm not clear on what the motivation for
> having a new alternative to this is.
`_Noreturn` remains a keyword for C23, but the headers are required to
use the new attribute. So we have to use a new name for the interfaces
that can be mapped to the old or new feature according to the needs.
> I don't see how __inline_or_static makes sense at all. (Non-static)
> inline has very different semantics from static
sure
> and they cannot be used interchangibly as a "use whichever the
> compiler supports".
This macro is only meant to make a difference for pre-C99 compilers,
which we still seem to support.
> We do not use non-static inline at all in musl,
> and I'm not aware of any place it would be useful in the public
> headers.
This comes in later, obvious.
Thanks
Jₑₙₛ
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