[MINIOS PATCH] lib.h: remove BUILD_BUG_ON

[MINIOS PATCH] lib.h: remove BUILD_BUG_ON

[Wei Liu]

BUILD_BUG_ON should not appear in a public-facing header, otherwise it
risks clashing with macro with the same name in other code bases. I
encountered such issue when trying to add BUILD_BUG_ON to a private
header in Xen's gnttab library.

Ideally BUILD_BUG_ON should be moved to a private header, but there is
actually no user of it in mini-os tree, just remove it.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
---
 include/lib.h | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/include/lib.h b/include/lib.h
index 39d6a18..e7155e2 100644
--- a/include/lib.h
+++ b/include/lib.h
@@ -54,15 +54,6 @@
 #include <xen/event_channel.h>
 #include "gntmap.h"
 
-#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
-#define BUILD_BUG_ON(cond) ({ _Static_assert(!(cond), "!(" #cond ")"); })
-#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>
-- 
2.1.4


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Re: [MINIOS PATCH] lib.h: remove BUILD_BUG_ON

[Samuel Thibault]

Wei Liu, on Fri 12 Aug 2016 15:01:07 +0100, wrote:
> BUILD_BUG_ON should not appear in a public-facing header, otherwise it
> risks clashing with macro with the same name in other code bases. I
> encountered such issue when trying to add BUILD_BUG_ON to a private
> header in Xen's gnttab library.
> 
> Ideally BUILD_BUG_ON should be moved to a private header, but there is
> actually no user of it in mini-os tree, just remove it.
> 
> Signed-off-by: Wei Liu <wei.liu2@citrix.com>

Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

> ---
>  include/lib.h | 9 ---------
>  1 file changed, 9 deletions(-)
> 
> diff --git a/include/lib.h b/include/lib.h
> index 39d6a18..e7155e2 100644
> --- a/include/lib.h
> +++ b/include/lib.h
> @@ -54,15 +54,6 @@
>  #include <xen/event_channel.h>
>  #include "gntmap.h"
>  
> -#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)
> -#define BUILD_BUG_ON(cond) ({ _Static_assert(!(cond), "!(" #cond ")"); })
> -#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>
> -- 
> 2.1.4
> 

-- 
Samuel
(03:13:14) <j> bon
(03:13:19) <j> il est tard :p
(03:13:25) <g> c'est l'heure de manger
(03:13:38) <j> hm j'ai mangé à 1h moi, j'ai des horaires raisonnables

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Re: [MINIOS PATCH] lib.h: remove BUILD_BUG_ON

[Wei Liu]

On Fri, Aug 12, 2016 at 04:02:11PM +0200, Samuel Thibault wrote:
> Wei Liu, on Fri 12 Aug 2016 15:01:07 +0100, wrote:
> > BUILD_BUG_ON should not appear in a public-facing header, otherwise it
> > risks clashing with macro with the same name in other code bases. I
> > encountered such issue when trying to add BUILD_BUG_ON to a private
> > header in Xen's gnttab library.
> > 
> > Ideally BUILD_BUG_ON should be moved to a private header, but there is
> > actually no user of it in mini-os tree, just remove it.
> > 
> > Signed-off-by: Wei Liu <wei.liu2@citrix.com>
> 
> Acked-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
> 

Actually some stuff in stubdom depends on mini-os leaking BUILD_BUG_ON,
while some actively work around the leaking of some other macros.

I will hold off putting in this patch for now.

Wei.

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