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@xxxxxxxxxxxxxxxxxx>
---
Changes since v1:
* When _Static_assert() is not available, rely on the previously used
sizeof() trick, as suggested by Lucas de Marchi.
---
configure.ac | 6 ++++++
libkmod/macro.h | 5 +++++
2 files changed, 11 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..10392a3 100644
--- a/libkmod/macro.h
+++ b/libkmod/macro.h
@@ -21,8 +21,13 @@
#include <stddef.h>
+#if defined(HAVE_STATIC_ASSERT)
#define assert_cc(expr) \
_Static_assert((expr), #expr)
+#else
+#define assert_cc(expr) \
+ do { (void) sizeof(char [1 - 2*!(expr)]); } while(0)
+#endif
#if HAVE_TYPEOF
#define check_types_match(expr1, expr2) \
--
1.8.1.2
--
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