LXR linux/include/linux/build

   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 int), 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) ((int)(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 */
  81