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        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_MSG - break compile if a condition is true & emit supplied

 *		      error message.

 * @condition: the condition which the compiler should know is false.

 *

 * See BUILD_BUG_ON for description.

 */

#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)

/**

 * 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.

 */

#ifndef __OPTIMIZE__

#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))

#else

#define BUILD_BUG_ON(condition) \

	BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)

#endif

/**

 * BUILD_BUG - break compile if used.

 *

 * If you have some code that you expect the compiler to eliminate at

 * build time, you should use BUILD_BUG to detect if it is

 * unexpectedly used.

 */