Re: [PATCH v2 1/3] compat/posix.h: track SA_RESTART fallback

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 25, 2025, 16:07 UTC
Message-ID: <xmqq4iw3yfd8.fsf@gitster.g>
In-Reply-To: <e82b7425bbc2540fa5ef3fd4584e6f902485d064.1750836928.git.gitgitgadget@gmail.com>

"Carlo Marcelo Arenas Belón via GitGitGadget" <gitgitgadget@gmail.com> writes:

Show 9 quoted lines

> +# Define USE_NON_POSIX_SIGNAL if don't have support for SA_RESTART or
> +# prefer using ANSI C signal() over POSIX sigaction()
> +
> +AC_CACHE_CHECK([whether SA_RESTART is supported], [ac_cv_siginterrupt], [
> +	AC_COMPILE_IFELSE(
> +		[AC_LANG_PROGRAM([#include <signal.h>], [[
> +		#ifdef SA_RESTART
> +		#endif
> +		siginterrupt(SIGCHLD, 1)

This is curious. What is this #ifdef/#endif doing that does not have anything in it?

Show 7 quoted lines

> +		]])],[ac_cv_siginterrupt=yes],[
> +			ac_cv_siginterrupt=no
> +			USE_NON_POSIX_SIGNAL=UnfortunatelyYes
> +		]
> +	)
> +])
> +GIT_CONF_SUBST([USE_NON_POSIX_SIGNAL])