Messages in this thread Patch in this message |  | | From | Vegard Nossum <> | Subject | [PATCH] compiler.h: fix error in BUILD_BUG_ON() reporting | Date | Tue, 31 Mar 2020 13:26:37 +0200 |
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compiletime_assert() uses __LINE__ to create a unique function name. This means that if you have more than one BUILD_BUG_ON() in the same source line (which can happen if they appear e.g. in a macro), then the error message from the compiler might output the wrong condition.
For this source file:
#include <linux/build_bug.h>
#define macro() \ BUILD_BUG_ON(1); \ BUILD_BUG_ON(0);
void foo() { macro(); }
gcc would output:
./include/linux/compiler.h:350:38: error: call to ‘__compiletime_assert_9’ declared with attribute error: BUILD_BUG_ON failed: 0 _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
However, it was not the BUILD_BUG_ON(0) that failed, so it should say 1 instead of 0. With this patch, we use __COUNTER__ instead of __LINE__, so each BUILD_BUG_ON() gets a different function name and the correct condition is printed:
./include/linux/compiler.h:350:38: error: call to ‘__compiletime_assert_0’ declared with attribute error: BUILD_BUG_ON failed: 1 _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__)
Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Ian Abbott <abbotti@mev.co.uk> Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> --- include/linux/compiler.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 5e88e7e33abec..034b0a644efcc 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -347,7 +347,7 @@ static inline void *offset_to_ptr(const int *off) * compiler has support to do so. */ #define compiletime_assert(condition, msg) \ - _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__) + _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) #define compiletime_assert_atomic_type(t) \ compiletime_assert(__native_word(t), \ -- 2.16.1.72.g5be1f00a9.dirty
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