Re: [Xen-devel] [PATCH 1/3] mini-os: add BUILD_BUG_ON()

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>]

Jan Beulich, le Wed 02 Jul 2014 15:25:25 +0100, a écrit :
> Just copy over what the hypervisor currently uses.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

Acked-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>

> --- a/extras/mini-os/include/lib.h
> +++ b/extras/mini-os/include/lib.h
> @@ -54,6 +54,20 @@
>  #include <xen/event_channel.h>
>  #include "gntmap.h"
>  
> +#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
> +/* Force a compilation error if condition is true */
> +#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(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
> +
>  #ifdef HAVE_LIBC
>  #include <sys/queue.h>
>  #include <stdio.h>
> 
> 
> 

> mini-os: add BUILD_BUG_ON()
> 
> Just copy over what the hypervisor currently uses.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> --- a/extras/mini-os/include/lib.h
> +++ b/extras/mini-os/include/lib.h
> @@ -54,6 +54,20 @@
>  #include <xen/event_channel.h>
>  #include "gntmap.h"
>  
> +#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
> +/* Force a compilation error if condition is true */
> +#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(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
> +
>  #ifdef HAVE_LIBC
>  #include <sys/queue.h>
>  #include <stdio.h>


-- 
Samuel
<s> je la connaissais pas celle la : "make: Entering an unknown directory"
 -+- #ens-mim -+-

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