root/include/linux/build_bug.h

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INCLUDED FROM


   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_BUILD_BUG_H
   3 #define _LINUX_BUILD_BUG_H
   4 
   5 #include <linux/compiler.h>
   6 
   7 #ifdef __CHECKER__
   8 #define BUILD_BUG_ON_ZERO(e) (0)
   9 #else /* __CHECKER__ */
  10 /*
  11  * Force a compilation error if condition is true, but also produce a
  12  * result (of value 0 and type size_t), so the expression can be used
  13  * e.g. in a structure initializer (or where-ever else comma expressions
  14  * aren't permitted).
  15  */
  16 #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:(-!!(e)); }))
  17 #endif /* __CHECKER__ */
  18 
  19 /* Force a compilation error if a constant expression is not a power of 2 */
  20 #define __BUILD_BUG_ON_NOT_POWER_OF_2(n)        \
  21         BUILD_BUG_ON(((n) & ((n) - 1)) != 0)
  22 #define BUILD_BUG_ON_NOT_POWER_OF_2(n)                  \
  23         BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
  24 
  25 /*
  26  * BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the
  27  * expression but avoids the generation of any code, even if that expression
  28  * has side-effects.
  29  */
  30 #define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
  31 
  32 /**
  33  * BUILD_BUG_ON_MSG - break compile if a condition is true & emit supplied
  34  *                    error message.
  35  * @condition: the condition which the compiler should know is false.
  36  *
  37  * See BUILD_BUG_ON for description.
  38  */
  39 #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
  40 
  41 /**
  42  * BUILD_BUG_ON - break compile if a condition is true.
  43  * @condition: the condition which the compiler should know is false.
  44  *
  45  * If you have some code which relies on certain constants being equal, or
  46  * some other compile-time-evaluated condition, you should use BUILD_BUG_ON to
  47  * detect if someone changes it.
  48  */
  49 #define BUILD_BUG_ON(condition) \
  50         BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
  51 
  52 /**
  53  * BUILD_BUG - break compile if used.
  54  *
  55  * If you have some code that you expect the compiler to eliminate at
  56  * build time, you should use BUILD_BUG to detect if it is
  57  * unexpectedly used.
  58  */
  59 #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
  60 
  61 /**
  62  * static_assert - check integer constant expression at build time
  63  *
  64  * static_assert() is a wrapper for the C11 _Static_assert, with a
  65  * little macro magic to make the message optional (defaulting to the
  66  * stringification of the tested expression).
  67  *
  68  * Contrary to BUILD_BUG_ON(), static_assert() can be used at global
  69  * scope, but requires the expression to be an integer constant
  70  * expression (i.e., it is not enough that __builtin_constant_p() is
  71  * true for expr).
  72  *
  73  * Also note that BUILD_BUG_ON() fails the build if the condition is
  74  * true, while static_assert() fails the build if the expression is
  75  * false.
  76  */
  77 #define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr)
  78 #define __static_assert(expr, msg, ...) _Static_assert(expr, msg)
  79 
  80 #endif  /* _LINUX_BUILD_BUG_H */

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