LXR uboot/include/linux/bug.h

   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 */
  56