* [PATCH] Add configure check for _Static_assert()
@ 2013-08-28 15:33 Thomas Petazzoni
2013-08-29 3:55 ` Lucas De Marchi
0 siblings, 1 reply; 5+ messages in thread
From: Thomas Petazzoni @ 2013-08-28 15:33 UTC (permalink / raw)
To: linux-modules; +Cc: thomas.petazzoni
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>
---
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
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] Add configure check for _Static_assert()
2013-08-28 15:33 [PATCH] Add configure check for _Static_assert() Thomas Petazzoni
@ 2013-08-29 3:55 ` Lucas De Marchi
2013-08-29 7:49 ` Thomas Petazzoni
0 siblings, 1 reply; 5+ messages in thread
From: Lucas De Marchi @ 2013-08-29 3:55 UTC (permalink / raw)
To: Thomas Petazzoni; +Cc: linux-modules
Hi Thomas,
On Wed, Aug 28, 2013 at 12:33 PM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> 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@free-electrons.com>
> ---
> 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
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] Add configure check for _Static_assert()
2013-08-29 3:55 ` Lucas De Marchi
@ 2013-08-29 7:49 ` Thomas Petazzoni
2013-08-29 20:19 ` Lucas De Marchi
2013-09-06 12:58 ` Lucas De Marchi
0 siblings, 2 replies; 5+ messages in thread
From: Thomas Petazzoni @ 2013-08-29 7:49 UTC (permalink / raw)
To: Lucas De Marchi; +Cc: linux-modules
Dear Lucas De Marchi,
On Thu, 29 Aug 2013 00:55:04 -0300, Lucas De Marchi wrote:
> Hi Thomas,
>
> On Wed, Aug 28, 2013 at 12:33 PM, Thomas Petazzoni
> <thomas.petazzoni@free-electrons.com> 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?
It's not a distro. As you know, I work on the Buildroot project, a tool
that builds rootfs for embedded Linux systems using cross-compilation.
One of the package we have is obviously kmod, but since we support a
wide range of architectures, not all of them are necessarily fully
up-to-date in terms of compiler version. The specific example that
raised the problem is a gcc 4.5.x toolchain for PowerPC provided by
Mentor Graphics Sourcery CodeBench (formerly known as CodeSourcery).
> > +#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)
Sure, will fix this and resend.
Thanks!
Thomas
--
Thomas Petazzoni, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] Add configure check for _Static_assert()
2013-08-29 7:49 ` Thomas Petazzoni
@ 2013-08-29 20:19 ` Lucas De Marchi
2013-09-06 12:58 ` Lucas De Marchi
1 sibling, 0 replies; 5+ messages in thread
From: Lucas De Marchi @ 2013-08-29 20:19 UTC (permalink / raw)
To: Thomas Petazzoni; +Cc: Lucas De Marchi, linux-modules
On Thu, Aug 29, 2013 at 4:49 AM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> Dear Lucas De Marchi,
>
> On Thu, 29 Aug 2013 00:55:04 -0300, Lucas De Marchi wrote:
>> Hi Thomas,
>>
>> On Wed, Aug 28, 2013 at 12:33 PM, Thomas Petazzoni
>> <thomas.petazzoni@free-electrons.com> 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?
>
> It's not a distro. As you know, I work on the Buildroot project, a tool
> that builds rootfs for embedded Linux systems using cross-compilation.
> One of the package we have is obviously kmod, but since we support a
> wide range of architectures, not all of them are necessarily fully
> up-to-date in terms of compiler version. The specific example that
> raised the problem is a gcc 4.5.x toolchain for PowerPC provided by
> Mentor Graphics Sourcery CodeBench (formerly known as CodeSourcery).
ok
>
>> > +#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)
>
> Sure, will fix this and resend.
ok
Lucas De Marchi
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] Add configure check for _Static_assert()
2013-08-29 7:49 ` Thomas Petazzoni
2013-08-29 20:19 ` Lucas De Marchi
@ 2013-09-06 12:58 ` Lucas De Marchi
1 sibling, 0 replies; 5+ messages in thread
From: Lucas De Marchi @ 2013-09-06 12:58 UTC (permalink / raw)
To: Thomas Petazzoni; +Cc: Lucas De Marchi, linux-modules
On Thu, Aug 29, 2013 at 4:49 AM, Thomas Petazzoni
<thomas.petazzoni@free-electrons.com> wrote:
> Dear Lucas De Marchi,
>
> On Thu, 29 Aug 2013 00:55:04 -0300, Lucas De Marchi wrote:
>> Hi Thomas,
>>
>> On Wed, Aug 28, 2013 at 12:33 PM, Thomas Petazzoni
>> <thomas.petazzoni@free-electrons.com> 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?
>
> It's not a distro. As you know, I work on the Buildroot project, a tool
> that builds rootfs for embedded Linux systems using cross-compilation.
> One of the package we have is obviously kmod, but since we support a
> wide range of architectures, not all of them are necessarily fully
> up-to-date in terms of compiler version. The specific example that
> raised the problem is a gcc 4.5.x toolchain for PowerPC provided by
> Mentor Graphics Sourcery CodeBench (formerly known as CodeSourcery).
>
>> > +#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)
>
> Sure, will fix this and resend.
Ping.
Lucas De Marchi
^ permalink raw reply [flat|nested] 5+ messages in thread
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2013-08-28 15:33 [PATCH] Add configure check for _Static_assert() Thomas Petazzoni
2013-08-29 3:55 ` Lucas De Marchi
2013-08-29 7:49 ` Thomas Petazzoni
2013-08-29 20:19 ` Lucas De Marchi
2013-09-06 12:58 ` Lucas De Marchi
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