[PATCH weston] configure: fix sys/sysmacros.h check

[Emil Velikov]

On 18 December 2017 at 08:24, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> From: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
>
> This patch is a copy of
> https://cgit.freedesktop.org/mesa/drm/commit/?id=7040fea0280bad527ed4b3d5eee7d7bfbf303efc
> by Adam Jackson.
>
> Commit 43c5a65b034a243700cf9c5bfbe6bcefb15f1161 "configure.ac: use
> AC_HEADER_MAJOR to detect major()/minor()" started using AC_HEADER_MAJOR
> to detect the header where major() is defined. This caused a regression
> on systems where glibc is still providing a deprecated definition of
> major() through sys/types.h, leading to a bunch of compiler warnings:
>
> /home/pq/git/weston/libweston/launcher-logind.c: In function ‘launcher_logind_open’:
> /home/pq/git/weston/libweston/launcher-logind.c:182:13: warning: In the GNU C Library, "major" is defined
>  by <sys/sysmacros.h>. For historical compatibility, it is
>  currently defined by <sys/types.h> as well, but we plan to
>  remove this soon. To use "major", include <sys/sysmacros.h>
>  directly. If you did not intend to use a system-defined macro
>  "major", you should undefine it after including <sys/types.h>.
>   fd = launcher_logind_take_device(wl, major(st.st_rdev),
>
> The issue has been discussed earlier on
> https://lists.gnu.org/archive/html/autoconf/2016-09/msg00013.html
>
> Work around the issue by causing the warning to trigger a build failure
> inside AC_HEADER_MAJOR test, so that we get MAJOR_IN_SYSMACROS defined.
>
> Cc: Adam Jackson <ajax at redhat.com>
> Cc: Emil Velikov <emil.l.velikov at gmail.com>
> Cc: Sergei Trofimovich <slyfox at gentoo.org>
> Signed-off-by: Pekka Paalanen <pekka.paalanen at collabora.co.uk>
> ---
>  configure.ac | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/configure.ac b/configure.ac
> index d1b5f471..285c2efd 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -34,7 +34,11 @@ AC_CONFIG_MACRO_DIR([m4])
>
>  AC_USE_SYSTEM_EXTENSIONS
>  AC_SYS_LARGEFILE
> +
> +save_CFLAGS="$CFLAGS"
> +export CFLAGS="$CFLAGS -Werror"
>  AC_HEADER_MAJOR
> +CFLAGS="$save_CFLAGS"
>

Reviewed-by: Emil Velikov <emil.velikov at collabora.com>

-Emil