Hi Thomas,
On Wed, Aug 28, 2013 at 12:33 PM, Thomas Petazzoni
<thomas.petazzoni@xxxxxxxxxxxxxxxxxx> wrote:
> 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
What distro is still in gcc 4.6? Is it a LTS one?
> 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>
> ---
> 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)
could you then define it similarly to what it was before then in this #else?
I think this would do it (totally untested) with the downside of an
ugly build error.
#define assert_cc(expr) \
do { (void) sizeof(char [1 - 2*!(expr)]); } while(0)
thanks
Lucas De Marchi
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