]> git.baikalelectronics.ru Git - kernel.git/commit
build_bug.h: add wrapper for _Static_assert
authorRasmus Villemoes <linux@rasmusvillemoes.dk>
Fri, 8 Mar 2019 00:27:00 +0000 (16:27 -0800)
committerLinus Torvalds <torvalds@linux-foundation.org>
Fri, 8 Mar 2019 02:31:59 +0000 (18:31 -0800)
commit6ae32334cc71b9fb22c0189d10e4c6ef0ea21558
treec2b2cd40eb47488f1e6c155365e14436b76f150f
parent5f29a26b3e141fe1f1f9830cc3b317c0c51c7d65
build_bug.h: add wrapper for _Static_assert

BUILD_BUG_ON() is a little annoying, since it cannot be used outside
function scope.  So one cannot put assertions about the sizeof() a
struct next to the struct definition, but has to hide that in some more
or less arbitrary function.

Since gcc 4.6 (which is now also the required minimum), there is support
for the C11 _Static_assert in all C modes, including gnu89.  So add a
simple wrapper for that.

_Static_assert() requires a message argument, which is usually quite
redundant (and I believe that bug got fixed at least in newer C++
standards), but we can easily work around that with a little macro
magic, making it optional.

For example, adding

  static_assert(sizeof(struct printf_spec) == 8);

in vsprintf.c and modifying that struct to violate it, one gets

./include/linux/build_bug.h:78:41: error: static assertion failed: "sizeof(struct printf_spec) == 8"
 #define __static_assert(expr, msg, ...) _Static_assert(expr, "" msg "")

godbolt.org suggests that _Static_assert() has been support by clang
since at least 3.0.0.

Link: http://lkml.kernel.org/r/20190208203015.29702-1-linux@rasmusvillemoes.dk
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luc Van Oostenryck <luc.vanoostenryck@gmail.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/build_bug.h