[libvirt] [PATCH 2/2] sys_types: avoid glibc 2.25 warnings about major()

Todo: tweak sys_types_h.m4 comment before pushing glibc 2.25 is deprecating the namespace pollution of <sys/types.h> injecting major(), minor(), and makedev() into the compilation environment, with a warning that insists that users include <sys/sysmacros.h> instead. However, because the expansion of AC_HEADER_MAJOR didn't bother checking sys/sysmacros.h until after probing whether sys/types.h pollutes the namespace, it was not defining MAJOR_IN_SYSMACROS, with the result that code compiled with -Werror chokes on the deprecation warnings because it was not including sysmacros.h. Backport the autoconf fix, so that gnulib projects avoid the warnings even when using older autoconf. * m4/sys_types_h.m4 (AC_HEADER_MAJOR): Replace broken version in older autoconf. * doc/posix-headers/sys_types.texi (sys/types.h): Document fix. * doc/glibc-functions/gnu_dev_major.texi (gnu_dev_major): Likewise. * doc/glibc-functions/gnu_dev_makedev.texi (gnu_dev_makedev): Likewise. * doc/glibc-functions/gnu_dev_minor.texi (gnu_dev_minor): Likewise. Signed-off-by: Eric Blake <eblake(a)redhat.com&gt; --- Obviously, I'll be tweaking this slightly to list an actual commit id that gets pushed to autoconf, but posting now for review. ChangeLog | 8 ++++++++ doc/glibc-functions/gnu_dev_major.texi | 4 ++++ doc/glibc-functions/gnu_dev_makedev.texi | 4 ++++ doc/glibc-functions/gnu_dev_minor.texi | 4 ++++ doc/posix-headers/sys_types.texi | 6 ++++++ m4/sys_types_h.m4 | 27 ++++++++++++++++++++++++++- 6 files changed, 52 insertions(+), 1 deletion(-) diff --git a/ChangeLog b/ChangeLog index ae0816d..1e694e6 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,5 +1,13 @@ 2016-09-14 Eric Blake <eblake(a)redhat.com&gt; + sys_types: avoid glibc 2.25 warnings about major() + * m4/sys_types_h.m4 (AC_HEADER_MAJOR): Replace broken version in + older autoconf. + * doc/posix-headers/sys_types.texi (sys/types.h): Document fix. + * doc/glibc-functions/gnu_dev_major.texi (gnu_dev_major): Likewise. + * doc/glibc-functions/gnu_dev_makedev.texi (gnu_dev_makedev): Likewise. + * doc/glibc-functions/gnu_dev_minor.texi (gnu_dev_minor): Likewise. + mountlist: include sysmacros.h for glibc * m4/mountlist.m4 (gl_PREREQ_MOUTLIST_EXTRA): Include AC_HEADER_MAJOR. diff --git a/doc/glibc-functions/gnu_dev_major.texi b/doc/glibc-functions/gnu_dev_major.texi index f7a2cfd..3a85300 100644 --- a/doc/glibc-functions/gnu_dev_major.texi +++ b/doc/glibc-functions/gnu_dev_major.texi @@ -6,6 +6,10 @@ gnu_dev_major Portability problems fixed by Gnulib: @itemize +The @code{AC_HEADER_MAJOR} macro in Autoconf 2.69 and earlier fails to +set @code{MAJOR_IN_SYSMACROS} when it detects namespace pollution in +(a)file{sys/types.h}; which in turn provokes deprecation warnings in +glibc 2.25. @end itemize Portability problems not fixed by Gnulib: diff --git a/doc/glibc-functions/gnu_dev_makedev.texi b/doc/glibc-functions/gnu_dev_makedev.texi index febd7f8..2738698 100644 --- a/doc/glibc-functions/gnu_dev_makedev.texi +++ b/doc/glibc-functions/gnu_dev_makedev.texi @@ -6,6 +6,10 @@ gnu_dev_makedev Portability problems fixed by Gnulib: @itemize +The @code{AC_HEADER_MAJOR} macro in Autoconf 2.69 and earlier fails to +set @code{MAJOR_IN_SYSMACROS} when it detects namespace pollution in +(a)file{sys/types.h}; which in turn provokes deprecation warnings in +glibc 2.25. @end itemize Portability problems not fixed by Gnulib: diff --git a/doc/glibc-functions/gnu_dev_minor.texi b/doc/glibc-functions/gnu_dev_minor.texi index a3dbefe..b4c789c 100644 --- a/doc/glibc-functions/gnu_dev_minor.texi +++ b/doc/glibc-functions/gnu_dev_minor.texi @@ -6,6 +6,10 @@ gnu_dev_minor Portability problems fixed by Gnulib: @itemize +The @code{AC_HEADER_MAJOR} macro in Autoconf 2.69 and earlier fails to +set @code{MAJOR_IN_SYSMACROS} when it detects namespace pollution in +(a)file{sys/types.h}; which in turn provokes deprecation warnings in +glibc 2.25. @end itemize Portability problems not fixed by Gnulib: diff --git a/doc/posix-headers/sys_types.texi b/doc/posix-headers/sys_types.texi index 29bb9ae..cf44bea 100644 --- a/doc/posix-headers/sys_types.texi +++ b/doc/posix-headers/sys_types.texi @@ -19,6 +19,12 @@ sys/types.h @item The type @code{mode_t} is not defined on some platforms: MSVC 9. +@item +Some systems leak definitions of @code{major}, @code{minor}, and +@code{makedev} through this header; however, when +(a)file{sys/sysmacros.h} exists, that file should also be included to +avoid deprecation warnings from the versions in this header: +glibc 2.25. @end itemize Portability problems not fixed by Gnulib: diff --git a/m4/sys_types_h.m4 b/m4/sys_types_h.m4 index b0aabb4..64be679 100644 --- a/m4/sys_types_h.m4 +++ b/m4/sys_types_h.m4 @@ -1,4 +1,4 @@ -# sys_types_h.m4 serial 5 +# sys_types_h.m4 serial 6 dnl Copyright (C) 2011-2016 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, @@ -22,3 +22,28 @@ AC_DEFUN_ONCE([gl_SYS_TYPES_H], AC_DEFUN([gl_SYS_TYPES_H_DEFAULTS], [ ]) + +# This works around a buggy version in autoconf <= 2.69. +# See <https://lists.gnu.org/archive/html/autoconf/2016-08/msg00014.html> + +m4_version_prereq([2.70], [], [ + +# This is taken from the following Autoconf patch: +# http://git.sv.gnu.org/cgit/autoconf.git/commit/?id=XXXXXXX + +m4_undefine([AC_HEADER_MAJOR]) +AC_DEFUN([AC_HEADER_MAJOR], +[AC_CHECK_HEADERS_ONCE([sys/types.h]) +AC_CHECK_HEADER([sys/mkdev.h], + [AC_DEFINE([MAJOR_IN_MKDEV], [1], + [Define to 1 if `major', `minor', and `makedev' are declared in + <mkdev.h>.])]) +if test $ac_cv_header_sys_mkdev_h = no; then + AC_CHECK_HEADER([sys/sysmacros.h], + [AC_DEFINE([MAJOR_IN_SYSMACROS], [1], + [Define to 1 if `major', `minor', and `makedev' are declared in + <sysmacros.h>.])]) +fi +]) + +]) -- 2.7.4