This is Clang's version of GCC's -Wmaybe-uninitialized. Up to this point, it has not been used because -Wuninitialized has been disabled, which also turns off -Wsometimes-uninitialized, meaning that we miss out on finding some bugs [1]. In my experience, it appears to be more accurate than GCC and catch some things that GCC can't. All of these warnings have now been fixed in -next across arm, arm64, and x86_64 defconfig/allyesconfig so this should be enabled for everyone to prevent more from easily creeping in. As of next-20190429: $ git log --oneline --grep="sometimes-uninitialized" | wc -l 45 [1]: https://lore.kernel.org/lkml/86649ee4-9794-77a3-502c-f4cd10019c36@xxxxxx/ Link: https://github.com/ClangBuiltLinux/linux/issues/381 Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx> --- Masahiro, I am not sure how you want to handle merging this with regards to all of the patches floating around in -next but I wanted to send this out to let everyone know this is ready to be turned on. Arnd, are there many remaning -Wsometimes-uninitialized warnings in randconfigs? scripts/Makefile.extrawarn | 1 + 1 file changed, 1 insertion(+) diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index 768306add591..f4332981ea85 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -72,5 +72,6 @@ KBUILD_CFLAGS += $(call cc-disable-warning, format) KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare) KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length) KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized) +KBUILD_CFLAGS += $(call cc-option, -Wsometimes-uninitialized) endif endif -- 2.21.0
