From: Miguel Ojeda Date: Thu, 14 Oct 2021 13:23:31 +0000 (+0200) Subject: compiler_types: mark __compiletime_assert failure as __noreturn X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=7c00621dcaeea206d7489b3e8b50b1864841ae69;p=linux.git compiler_types: mark __compiletime_assert failure as __noreturn `__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 Reviewed-by: Nathan Chancellor Reviewed-by: Nick Desaulniers Signed-off-by: Miguel Ojeda --- diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h index b6ff83a714ca9..ca1a66b8cd2f4 100644 --- a/include/linux/compiler_types.h +++ b/include/linux/compiler_types.h @@ -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)