keir at xen
Jul 26, 2012, 8:32 AM
Post #2 of 2
(31 views)
Permalink
|
|
Re: [PATCH] use C11's _Static_assert() for BUILD_BUG_ON etc when available
[In reply to]
|
|
On 26/07/2012 16:09, "Jan Beulich" <JBeulich [at] suse> wrote:
> This produces a more meaningful compiler diagnostic in case it happens
> to trigger.
>
> As a minor piece of cleanup, at once also use BUILD_BUG_ON_ZERO() to
> actually define BUILD_BUG_ON() in the legacy case, slightly reducing
> redundancy.
>
> Signed-off-by: Jan Beulich <jbeulich [at] suse>
Acked-by: Keir Fraser <keir [at] xen>
> --- a/xen/include/xen/lib.h
> +++ b/xen/include/xen/lib.h
> @@ -14,14 +14,20 @@ void __warn(char *file, int line);
> #define BUG_ON(p) do { if (unlikely(p)) BUG(); } while (0)
> #define WARN_ON(p) do { if (unlikely(p)) WARN(); } while (0)
>
> +#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
> /* Force a compilation error if condition is true */
> -#define BUILD_BUG_ON(condition) ((void)sizeof(struct { int:-!!(condition);
> }))
> +#define BUILD_BUG_ON(cond) ({ _Static_assert(!(cond), "!(" #cond ")"); })
>
> /* Force a compilation error if condition is true, but also produce a
> result (of value 0 and type size_t), so the expression can be used
> e.g. in a structure initializer (or where-ever else comma expressions
> aren't permitted). */
> -#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
> +#define BUILD_BUG_ON_ZERO(cond) \
> + sizeof(struct { _Static_assert(!(cond), "!(" #cond ")"); })
> +#else
> +#define BUILD_BUG_ON_ZERO(cond) sizeof(struct { int:-!!(cond); })
> +#define BUILD_BUG_ON(cond) ((void)BUILD_BUG_ON_ZERO(cond))
> +#endif
>
> #ifndef assert_failed
> #define assert_failed(p) \
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel [at] lists
> http://lists.xen.org/xen-devel
_______________________________________________
Xen-devel mailing list
Xen-devel [at] lists
http://lists.xen.org/xen-devel
|
static-assert.patch
