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| 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 | +#ifndef static_assert |
| 78 | +#define static_assert(expr, ...) __static_assert(expr, ##__VA_ARGS__, #expr) |
| 79 | +#define __static_assert(expr, msg, ...) _Static_assert(expr, msg) |
| 80 | +#endif // static_assert |
| 81 | + |
| 82 | +#endif /* _LINUX_BUILD_BUG_H */ |
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