Re: [PATCH] compat/posix.h: enable UNUSED warning messages for Clang
- From
Junio C Hamano <gitster@pobox.com>
- Date
- May 4, 2026, 01:10 UTC
- Message-ID
- <xmqq1pfsq8sd.fsf@gitster.g>
- In-Reply-To
- <20260503151210.36036-1-dominik.loidolt@univie.ac.at>
Dominik Loidolt <dominik.loidolt@univie.ac.at> writes:
Show 15 quoted lines
> Treat Clang like GCC 4.5+ so using an UNUSED parameter emits the
> intended warning message.
>
> 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.
>
> Clang identifies itself as GNUC 4.2.1 for compatibility, causing the
> current check to use the deprecated attribute without a message, even
> though Clang supports deprecated("...") since version 2.9 (2011).
>
> Signed-off-by: Dominik Loidolt <dominik.loidolt@univie.ac.at>
> ---
> I am not familiar with git's minimum compiler version but this patch
> drops support for Clang < 2.9 from 2011.Does this "drop support" because you force _all_ versions of Clang to use the "deprecated" attribute, even though you _know_ some older versions do not understand it? Don't these versions identify themselves so that you can do
#if defined(__clang__) && CLANG_VERSION >= 2.9
I do not know if the userbase of GCC and Clang upgrade with a similar cadence, or we seem to say that we care about GCC 4.5 (2010), so giving a similar version detection for Clang and exclude ones older than 2.9 sounds more appropriate.
Show 24 quoted lines
> Dominik
> P.S. This is my first patch sent by email. Please let me know if I
> missed something.
>
> compat/posix.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/compat/posix.h b/compat/posix.h
> index 245386fa4a..ed83a4d9d4 100644
> --- a/compat/posix.h
> +++ b/compat/posix.h
> @@ -35,7 +35,7 @@
> * 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) || defined(__clang__)
> #define UNUSED __attribute__((unused)) \
> __attribute__((deprecated ("parameter declared as UNUSED")))
> #elif defined(__GNUC__)
>
> base-commit: 67ad42147a7acc2af6074753ebd03d904476118f
> --
> 2.54.0