kmod: fix build failure on gcc < 4.6 caused by _Static_assert()

From d4a1e5daf0d50aa79ae0ed2f947f5657343cf2f7 Mon Sep 17 00:00:00 2001

From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Date: Wed, 28 Aug 2013 17:31:40 +0200

Subject: [PATCH] Add configure check for _Static_assert()

Commit 8efede20ef ("Use _Static_assert") introduced the usage of

_Static_assert(). However, _Static_assert() is a fairly new thing,

since it was introduced only in gcc 4.6. In order to support older

compilers, this patch adds a configure.in test that checks whether

_Static_assert() is usable or not, and adjust the behavior of the

assert_cc() macro accordingly.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Upstream-status: submitted

                 http://article.gmane.org/gmane.linux.kernel.modules/1136

---

 configure.ac    | 6 ++++++

 libkmod/macro.h | 4 ++++

 2 files changed, 10 insertions(+)

diff --git a/configure.ac b/configure.ac

index 40e54cf..cbe12f3 100644

--- a/configure.ac

+++ b/configure.ac

@@ -52,6 +52,12 @@ AC_CHECK_MEMBERS([struct stat.st_mtim], [], [], [#include <sys/stat.h>])

 # Check kernel headers

 AC_CHECK_HEADERS_ONCE([linux/module.h])

+AC_MSG_CHECKING([whether _Static_assert() is supported])

+AC_COMPILE_IFELSE(

+	[AC_LANG_SOURCE([[_Static_assert(1, "Test");]])],

+        [AC_DEFINE([HAVE_STATIC_ASSERT], [1], [Define is _Static_assert() is available])

+	 AC_MSG_RESULT([yes])],

+	[AC_MSG_RESULT([no])])

 #####################################################################

 # --with-

diff --git a/libkmod/macro.h b/libkmod/macro.h

index c6ba855..5992026 100644

--- a/libkmod/macro.h

+++ b/libkmod/macro.h

@@ -21,8 +21,12 @@

 #include <stddef.h>

+#if defined(HAVE_STATIC_ASSERT)

 #define assert_cc(expr) \

 	_Static_assert((expr), #expr)

+#else

+#define assert_cc(expr)

+#endif

 #if HAVE_TYPEOF

 #define check_types_match(expr1, expr2)		\

-- 

1.8.1.2

KMOD_INSTALL_STAGING = YES

KMOD_DEPENDENCIES = host-pkgconf

# Some patches are touching configure.in

KMOD_AUTORECONF = YES

# license info for libkmod only, conditionally add more below

KMOD_LICENSE = LGPLv2.1+

KMOD_LICENSE_FILES = libkmod/COPYING