linux-stable/include/linux/build_bug.h
Masahiro Yamada 32b395a133 build_bug.h: remove BUILD_BUG_ON_NULL()
This macro is only used by net/ipv6/mcast.c, but there is no reason
why it must be BUILD_BUG_ON_NULL().

Replace it with BUILD_BUG_ON_ZERO(), and remove BUILD_BUG_ON_NULL()
definition from <linux/build_bug.h>.

Link: http://lkml.kernel.org/r/1515121833-3174-3-git-send-email-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Ian Abbott <abbotti@mev.co.uk>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>
Cc: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-06 18:32:46 -08:00

83 lines
2.9 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_BUILD_BUG_H
#define _LINUX_BUILD_BUG_H
#include <linux/compiler.h>
#ifdef __CHECKER__
#define __BUILD_BUG_ON_NOT_POWER_OF_2(n) (0)
#define BUILD_BUG_ON_NOT_POWER_OF_2(n) (0)
#define BUILD_BUG_ON_ZERO(e) (0)
#define BUILD_BUG_ON_INVALID(e) (0)
#define BUILD_BUG_ON_MSG(cond, msg) (0)
#define BUILD_BUG_ON(condition) (0)
#define BUILD_BUG() (0)
#else /* __CHECKER__ */
/* Force a compilation error if a constant expression is not a power of 2 */
#define __BUILD_BUG_ON_NOT_POWER_OF_2(n) \
BUILD_BUG_ON(((n) & ((n) - 1)) != 0)
#define BUILD_BUG_ON_NOT_POWER_OF_2(n) \
BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
/*
* Force a compilation error if condition is true, but also produce a
* result (of value 0 and type size_t), so the expression can be used
* e.g. in a structure initializer (or where-ever else comma expressions
* aren't permitted).
*/
#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:(-!!(e)); }))
/*
* BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the
* expression but avoids the generation of any code, even if that expression
* has side-effects.
*/
#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
/**
* BUILD_BUG_ON_MSG - break compile if a condition is true & emit supplied
* error message.
* @condition: the condition which the compiler should know is false.
*
* See BUILD_BUG_ON for description.
*/
#define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
/**
* BUILD_BUG_ON - break compile if a condition is true.
* @condition: the condition which the compiler should know is false.
*
* If you have some code which relies on certain constants being equal, or
* some other compile-time-evaluated condition, you should use BUILD_BUG_ON to
* detect if someone changes it.
*
* The implementation uses gcc's reluctance to create a negative array, but gcc
* (as of 4.4) only emits that error for obvious cases (e.g. not arguments to
* inline functions). Luckily, in 4.3 they added the "error" function
* attribute just for this type of case. Thus, we use a negative sized array
* (should always create an error on gcc versions older than 4.4) and then call
* an undefined function with the error attribute (should always create an
* error on gcc 4.3 and later). If for some reason, neither creates a
* compile-time error, we'll still have a link-time error, which is harder to
* track down.
*/
#ifndef __OPTIMIZE__
#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
#else
#define BUILD_BUG_ON(condition) \
BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
#endif
/**
* BUILD_BUG - break compile if used.
*
* If you have some code that you expect the compiler to eliminate at
* build time, you should use BUILD_BUG to detect if it is
* unexpectedly used.
*/
#define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed")
#endif /* __CHECKER__ */
#endif /* _LINUX_BUILD_BUG_H */