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