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compiler_types: mark __compiletime_assert failure as __noreturn

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`__compiletime_assert` declares a fake `extern` function
which appears (to the compiler) to be called when the test fails.

Therefore, compilers may emit possibly-uninitialized warnings
in some cases, even if it will be an error anyway (for compilers
supporting the `error` attribute, e.g. GCC and Clang >= 14)
or a link failure (for those that do not, e.g. Clang < 14).

Annotating the fake function as `__noreturn` gives them
the information they need to avoid the warning,
e.g. see https://godbolt.org/z/x1v69jjYY.

Link: https://lore.kernel.org/llvm/202110100514.3h9CI4s0-lkp@intel.com/
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
This commit is contained in:
Miguel Ojeda 2021-10-14 15:23:31 +02:00
parent d08fd747d0
commit 7c00621dca
1 changed files with 7 additions and 1 deletions
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8
include/linux/compiler_types.h
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@ -298,7 +298,13 @@ struct ftrace_likely_data {
#ifdef __OPTIMIZE__
# define __compiletime_assert(condition, msg, prefix, suffix) \
do { \
extern void prefix ## suffix(void) __compiletime_error(msg); \
/* \
* __noreturn is needed to give the compiler enough \
* information to avoid certain possibly-uninitialized \
* warnings (regardless of the build failing). \
*/ \
__noreturn extern void prefix ## suffix(void) \
__compiletime_error(msg); \
if (!(condition)) \
prefix ## suffix(); \
} while (0)