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bug.h: sync BUILD_BUG stuff with Linux 4.13

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As commit 84b8bf6d5d ("bug.h: move BUILD_BUG_* defines to
include/linux/bug.h") noted, include/linux/bug.h was locally
modified for U-Boot because the name conflict of error() caused
build errors at that time.

Now error() is gone, so we can fully sync BUILD_BUG* with Linux.
These macros are just compile-time utilities.  Nothing depends on
platform code, so it should make sense to simply copy Linux's ones.

Please note Linux split BUILD_BUG stuff out into <linux/build_bug.h>
by commit bc6245e5efd7.  Let's follow it.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
This commit is contained in:
Masahiro Yamada 2017-09-16 14:10:44 +09:00 • committed by Tom Rini
parent f7d6b896d6
commit 059a48096c
3 changed files with 90 additions and 51 deletions
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51
include/linux/bug.h
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@ -1,55 +1,6 @@
#ifndef _LINUX_BUG_H
#define _LINUX_BUG_H
#include <linux/compiler.h>
#ifdef __CHECKER__
#define BUILD_BUG_ON_NOT_POWER_OF_2(n) (0)
#define BUILD_BUG_ON_ZERO(e) (0)
#define BUILD_BUG_ON_NULL(e) ((void*)0)
#define BUILD_BUG_ON_INVALID(e) (0)
#define BUILD_BUG_ON(condition) (0)
#define BUILD_BUG() (0)
#else /* __CHECKER__ */
/* Force a compilation error if a constant expression is not a power of 2 */
#define BUILD_BUG_ON_NOT_POWER_OF_2(n) \
BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
/* 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_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
/*
* BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the
* expression but avoids the generation of any code, even if that expression
* has side-effects.
*/
#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
/**
* BUILD_BUG_ON - break compile if a condition is true.
* @condition: the condition which the compiler should know is false.
*
* If you have some code which relies on certain constants being equal, or
* some other compile-time-evaluated condition, you should use BUILD_BUG_ON to
* detect if someone changes it.
*
* The implementation uses gcc's reluctance to create a negative array, but gcc
* (as of 4.4) only emits that error for obvious cases (e.g. not arguments to
* inline functions). Luckily, in 4.3 they added the "error" function
* attribute just for this type of case. Thus, we use a negative sized array
* (should always create an error on gcc versions older than 4.4) and then call
* an undefined function with the error attribute (should always create an
* error on gcc 4.3 and later). If for some reason, neither creates a
* compile-time error, we'll still have a link-time error, which is harder to
* track down.
*/
#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
#endif /* __CHECKER__ */
#include <linux/build_bug.h>
#endif /* _LINUX_BUG_H */