1#ifndef _LINUX_BUILD_BUG_H 2#define _LINUX_BUILD_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_NOT_POWER_OF_2(n) (0) 9#define BUILD_BUG_ON_ZERO(e) (0) 10#define BUILD_BUG_ON_NULL(e) ((void *)0) 11#define BUILD_BUG_ON_INVALID(e) (0) 12#define BUILD_BUG_ON_MSG(cond, msg) (0) 13#define BUILD_BUG_ON(condition) (0) 14#define BUILD_BUG() (0) 15#else /* __CHECKER__ */ 16 17/* Force a compilation error if a constant expression is not a power of 2 */ 18#define __BUILD_BUG_ON_NOT_POWER_OF_2(n) \ 19 BUILD_BUG_ON(((n) & ((n) - 1)) != 0) 20#define BUILD_BUG_ON_NOT_POWER_OF_2(n) \ 21 BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0)) 22 23/* 24 * Force a compilation error if condition is true, but also produce a 25 * result (of value 0 and type size_t), so the expression can be used 26 * e.g. in a structure initializer (or where-ever else comma expressions 27 * aren't permitted). 28 */ 29#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:(-!!(e)); })) 30#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:(-!!(e)); })) 31 32/* 33 * BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the 34 * expression but avoids the generation of any code, even if that expression 35 * has side-effects. 36 */ 37#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e)))) 38 39/** 40 * BUILD_BUG_ON_MSG - break compile if a condition is true & emit supplied 41 * error message. 42 * @condition: the condition which the compiler should know is false. 43 * 44 * See BUILD_BUG_ON for description. 45 */ 46#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) 47 48/** 49 * BUILD_BUG_ON - break compile if a condition is true. 50 * @condition: the condition which the compiler should know is false. 51 * 52 * If you have some code which relies on certain constants being equal, or 53 * some other compile-time-evaluated condition, you should use BUILD_BUG_ON to 54 * detect if someone changes it. 55 * 56 * The implementation uses gcc's reluctance to create a negative array, but gcc 57 * (as of 4.4) only emits that error for obvious cases (e.g. not arguments to 58 * inline functions). Luckily, in 4.3 they added the "error" function 59 * attribute just for this type of case. Thus, we use a negative sized array 60 * (should always create an error on gcc versions older than 4.4) and then call 61 * an undefined function with the error attribute (should always create an 62 * error on gcc 4.3 and later). If for some reason, neither creates a 63 * compile-time error, we'll still have a link-time error, which is harder to 64 * track down. 65 */ 66#ifndef __OPTIMIZE__ 67#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)])) 68#else 69#define BUILD_BUG_ON(condition) \ 70 BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) 71#endif 72 73/** 74 * BUILD_BUG - break compile if used. 75 * 76 * If you have some code that you expect the compiler to eliminate at 77 * build time, you should use BUILD_BUG to detect if it is 78 * unexpectedly used. 79 */ 80#define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed") 81 82/** 83 * static_assert - check integer constant expression at build time 84 * 85 * static_assert() is a wrapper for the C11 _Static_assert, with a 86 * little macro magic to make the message optional (defaulting to the 87 * stringification of the tested expression). 88 * 89 * Contrary to BUILD_BUG_ON(), static_assert() can be used at global 90 * scope, but requires the expression to be an integer constant 91 * expression (i.e., it is not enough that __builtin_constant_p() is 92 * true for expr). 93 * 94 * Also note that BUILD_BUG_ON() fails the build if the condition is 95 * true, while static_assert() fails the build if the expression is 96 * false. 97 */ 98#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr) 99#define __static_assert(expr, msg, ...) _Static_assert(expr, msg) 100 101#endif /* __CHECKER__ */ 102 103#endif /* _LINUX_BUILD_BUG_H */ 104