From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
To: Joseph Myers <joseph@codesourcery.com>
Cc: libc-alpha@sourceware.org, Paul Eggert <eggert@cs.ucla.edu>
Subject: Re: [PATCH 1/5] misc: Sync cdefs.h with gnulib
Date: Wed, 13 Jan 2021 15:30:57 -0300 [thread overview]
Message-ID: <1ffd0c02-26d3-020f-087e-deb9a3729c42@linaro.org> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2101131759560.1278751@digraph.polyomino.org.uk>
On 13/01/2021 15:09, Joseph Myers wrote:
> On Wed, 13 Jan 2021, Adhemerval Zanella via Libc-alpha wrote:
>
>> +#if defined __STDC_VERSION__ && 201710L < __STDC_VERSION__
>> +# define __attribute_maybe_unused__ [[__maybe_unused__]]
>
> I don't think that will work with GCC 9 -std=c2x or -std=gnu2x (support
> for [[]] attributes was added in GCC 10). This macro isn't used at all in
> glibc, what compilers and options are expected to be supported for it in
> gnulib?
>
> If you compare __STDC_VERSION__ with the version for the previous
> standard, and intend to support compilers such as GCC 9 -std=gnu2x, you
> need to deal with incomplete implementations using placeholder values
> (202000L in this case). (You might have incomplete implementations even
> comparing with the final value used for C23, but they're less likely to be
> so incomplete.)
>
> When you're supporting [[__maybe_unused__]] you might want to support it
> for C++17 as well as C2x. Or is this macro in gnulib only intended to be
> used in C code, not C++?
>
It is only used on C code, more specially for lib/malloc/dynarray-skeleton.c.
And I am no sure if gnulib has active support -std=c2x or -std=gnu2x and
I think Paul can give us a better idea on how to support this better on
gnulib side.
next prev parent reply other threads:[~2021-01-13 18:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-13 16:58 Adhemerval Zanella
2021-01-13 16:58 ` [PATCH 2/5] malloc: Sync dynarray " Adhemerval Zanella
2021-02-09 19:12 ` Adhemerval Zanella
2021-01-13 16:58 ` [PATCH v2 3/5] regex: remove alloca usage on regex set_regs Adhemerval Zanella
2021-02-09 19:12 ` Adhemerval Zanella
2021-01-13 16:58 ` [PATCH v2 4/5] regexec: remove alloca usage in build_trtable Adhemerval Zanella
2021-02-09 19:12 ` Adhemerval Zanella
2021-01-13 16:58 ` [PATCH v2 5/5] regex: stop using alloca Adhemerval Zanella
2021-02-09 19:12 ` Adhemerval Zanella
2021-01-13 18:09 ` [PATCH 1/5] misc: Sync cdefs.h with gnulib Joseph Myers
2021-01-13 18:30 ` Adhemerval Zanella [this message]
2021-02-09 14:07 ` Adhemerval Zanella
2021-01-13 19:19 ` Paul Eggert
2021-01-13 19:21 ` Adhemerval Zanella
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