From: Patrick Steinhardt <ps@pks•im>
To: Dominik Loidolt <dominik.loidolt@univie•ac.at>
Cc: gitster@pobox•com, git@vger•kernel.org, asedeno@MIT•EDU,
asedeno@google•com, avarab@gmail•com
Subject: Re: [PATCH v2] compat/posix.h: enable UNUSED warning messages for Clang
Date: Fri, 5 Jun 2026 12:40:42 +0200 [thread overview]
Message-ID: <aiKnqlI7WdcskDAs@pks.im> (raw)
In-Reply-To: <20260605094647.94805-1-dominik.loidolt@univie.ac.at>
On Fri, Jun 05, 2026 at 11:46:47AM +0200, Dominik Loidolt wrote:
> Use a dedicated Clang version check for the UNUSED macro.
>
> Commit 7c07f36ad2 (git-compat-util.h: GCC deprecated message arg only in
> GCC 4.5+, 2022-10-05) restricted use of the deprecated attribute's
> message argument in the UNUSED macro to GCC 4.5 or newer.
Ah. I was briefly wondering about this because the UNUSED macro already
works. But the important part here is that it's really only about better
diagnostics via the attribute message.
> Clang identifies itself as GNUC 4.2.1 for compatibility, so
> GIT_GNUC_PREREQ(4, 5) does not detect whether Clang supports the
> deprecated("...") form. Add GIT_CLANG_PREREQ() macro and use it to
> enable the UNUSED warning message for Clang 2.9 and newer.
There's a second user of `GIT_GNUC_PREREQ` in "git-compat-util.h", but
that user checks for GCC 3.1. And as Clang identifies as a newer version
we don't have to adapt any other callsites.
> diff --git a/compat/posix.h b/compat/posix.h
> index faaae1b655..88ad29d74b 100644
> --- a/compat/posix.h
> +++ b/compat/posix.h
> @@ -22,6 +22,17 @@
> #define GIT_GNUC_PREREQ(maj, min) 0
> #endif
>
> +/*
> + * Similar for Clang
> + */
Micronit, not worth rerolling over: this could have easily been a single
line: `/* Similar for Clang. */`
> +#if defined(__clang__) && defined(__clang_minor__) && defined(__clang_major__)
> +# define GIT_CLANG_PREREQ(maj, min) \
> + ((__clang_major__ > (maj)) || \
> + (__clang_major__ == (maj) && (__clang_minor__ >= (min))))
> +#else
> +# define GIT_CLANG_PREREQ(maj, min) 0
> +#endif
> +
> /*
> * UNUSED marks a function parameter that is always unused. It also
> * can be used to annotate a function, a variable, or a type that is
> @@ -35,7 +46,7 @@
> * When a parameter may be used or unused, depending on conditional
> * compilation, consider using MAYBE_UNUSED instead.
> */
> -#if GIT_GNUC_PREREQ(4, 5)
> +#if GIT_GNUC_PREREQ(4, 5) || GIT_CLANG_PREREQ(2, 9)
> #define UNUSED __attribute__((unused)) \
> __attribute__((deprecated ("parameter declared as UNUSED")))
> #elif defined(__GNUC__)
Makes sense, thanks!
Patrick
next prev parent reply other threads:[~2026-06-05 10:40 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-03 15:12 [PATCH] compat/posix.h: enable UNUSED warning messages for Clang Dominik Loidolt
2026-05-04 1:10 ` Junio C Hamano
2026-05-04 1:41 ` Junio C Hamano
2026-06-05 8:44 ` Dominik Loidolt
2026-06-05 9:46 ` [PATCH v2] " Dominik Loidolt
2026-06-05 10:40 ` Patrick Steinhardt [this message]
2026-06-05 11:50 ` Dominik Loidolt
2026-06-05 13:22 ` Patrick Steinhardt
2026-06-05 15:53 ` Dominik Loidolt
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