[J-u-boot.git] / include / linux / bug.h

#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__ */

#endif	/* _LINUX_BUG_H */
Commit	Line	Data
84b8bf6d MY	1	#ifndef _LINUX_BUG_H
	2	#define _LINUX_BUG_H
	3
	4	#include <linux/compiler.h>
	5
	6	#ifdef __CHECKER__
	7	#define BUILD_BUG_ON_NOT_POWER_OF_2(n) (0)
	8	#define BUILD_BUG_ON_ZERO(e) (0)
	9	#define BUILD_BUG_ON_NULL(e) ((void*)0)
	10	#define BUILD_BUG_ON_INVALID(e) (0)
	11	#define BUILD_BUG_ON(condition) (0)
	12	#define BUILD_BUG() (0)
	13	#else /* __CHECKER__ */
	14
	15	/* Force a compilation error if a constant expression is not a power of 2 */
	16	#define BUILD_BUG_ON_NOT_POWER_OF_2(n) \
	17	BUILD_BUG_ON((n) == 0 \|\| (((n) & ((n) - 1)) != 0))
	18
	19	/* Force a compilation error if condition is true, but also produce a
	20	result (of value 0 and type size_t), so the expression can be used
	21	e.g. in a structure initializer (or where-ever else comma expressions
	22	aren't permitted). */
	23	#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
	24	#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
	25
	26	/*
	27	* BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the
	28	* expression but avoids the generation of any code, even if that expression
	29	* has side-effects.
	30	*/
	31	#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
	32
	33	/**
	34	* BUILD_BUG_ON - break compile if a condition is true.
	35	* @condition: the condition which the compiler should know is false.
	36	*
	37	* If you have some code which relies on certain constants being equal, or
	38	* some other compile-time-evaluated condition, you should use BUILD_BUG_ON to
	39	* detect if someone changes it.
	40	*
	41	* The implementation uses gcc's reluctance to create a negative array, but gcc
	42	* (as of 4.4) only emits that error for obvious cases (e.g. not arguments to
	43	* inline functions). Luckily, in 4.3 they added the "error" function
	44	* attribute just for this type of case. Thus, we use a negative sized array
	45	* (should always create an error on gcc versions older than 4.4) and then call
	46	* an undefined function with the error attribute (should always create an
	47	* error on gcc 4.3 and later). If for some reason, neither creates a
	48	* compile-time error, we'll still have a link-time error, which is harder to
	49	* track down.
	50	*/
	51	#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
	52
	53	#endif /* __CHECKER__ */
	54
	55	#endif /* _LINUX_BUG_H */