[libvirt] [PATCH] Make sure sys/types.h is included after sys/sysmacros.h

[Daniel P. Berrange]

On Tue, Sep 06, 2016 at 03:46:59PM +0200, Michal Privoznik wrote:
> In the latest glibc, major() and minor() functions are marked as
> deprecated (glibc commit dbab6577):
> 
>   CC       util/libvirt_util_la-vircgroup.lo
> util/vircgroup.c: In function 'virCgroupGetBlockDevString':
> util/vircgroup.c:768:5: error: '__major_from_sys_types' is deprecated:
>   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 #undef it after including <sys/types.h>.
>   [-Werror=deprecated-declarations]
>      if (virAsprintf(&ret, "%d:%d ", major(sb.st_rdev), minor(sb.st_rdev)) < 0)
>      ^~
> In file included from /usr/include/features.h:397:0,
>                  from /usr/include/bits/libc-header-start.h:33,
>                  from /usr/include/stdio.h:28,
>                  from ../gnulib/lib/stdio.h:43,
>                  from util/vircgroup.c:26:
> /usr/include/sys/sysmacros.h:87:1: note: declared here
>  __SYSMACROS_DEFINE_MAJOR (__SYSMACROS_FST_IMPL_TEMPL)
>  ^
> 
> Moreover, in the glibc commit, there's suggestion to keep
> ordering of including of header files as implemented here.
> 
> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
> ---
> 
> This still won't solve the build issue completely as AC_HEADER_MAJOR still
> reports that major() is defined by sys/types.h instead of sys/sysmacros.h.
> But once they fix it, we are good too. Or we can use the following
> workaround in configure.ac:
> 
>   +old_CFLAGS=$CFLAGS
>   +CFLAGS+=" -Werror "
>    AC_HEADER_MAJOR
>   +CFLAGS=$old_CFLAGS

It isn't clear that AC_HEADER_MAJOR is actually doing anything
useful for us. Could we not simply remove the use of AC_HEADER_MAJOR
in configure.ac ? If not, then just re-implement the functionality
ourselves, so that we prioritize checking sys/sysmacros.h in
configure.


Regards,
Daniel
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