Messages in this thread Patch in this message | | | From | Linus Torvalds <> | Date | Sat, 13 Nov 2021 15:20:19 -0800 | Subject | Re: [GIT PULL] Enable -Wimplicit-fallthrough for Clang for 5.16-rc1 |
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On Sat, Nov 13, 2021 at 1:36 PM Gustavo A. R. Silva <gustavoars@kernel.org> wrote: > > This patch has been baking in linux-next for a couple of developement > cycles, now. So, I think we are pretty much ready to merge it into > mainline.
Ugh. It's also very ugly.
Wouldn't something like this (TOTALLY UNTESTED!) work and do the right thing?
This seems like a natural for a Kconfig decision.
Also, does -Wimplicit-fallthrough=5 work with clang too? That would simplify things a bit, and then we could just use a regular boolean and do
KBUILD_CFLAGS-$(CC_IMPLICIT_FALLTHROUGH) += -Wimplicit-fallthrough=5
in the Makefile, which is more in like with what we do for other config-time cflags..
Linus Makefile | 6 +----- init/Kconfig | 5 +++++ 2 files changed, 6 insertions(+), 5 deletions(-)
diff --git a/Makefile b/Makefile index d83d72c26aaa..9cf9d5c1ed8f 100644 --- a/Makefile +++ b/Makefile @@ -789,7 +789,7 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong KBUILD_CFLAGS += $(stackp-flags-y) KBUILD_CFLAGS-$(CONFIG_WERROR) += -Werror -KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) +KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH) ifdef CONFIG_CC_IS_CLANG KBUILD_CPPFLAGS += -Qunused-arguments @@ -801,10 +801,6 @@ KBUILD_CFLAGS += -Wno-gnu KBUILD_CFLAGS += -mno-global-merge else -# Warn about unmarked fall-throughs in switch statement. -# Disabled for clang while comment to attribute conversion happens and -# https://github.com/ClangBuiltLinux/linux/issues/636 is discussed. -KBUILD_CFLAGS += $(call cc-option,-Wimplicit-fallthrough=5,) # gcc inanely warns about local variables called 'main' KBUILD_CFLAGS += -Wno-main endif diff --git a/init/Kconfig b/init/Kconfig index 45bcaa8e7481..036b750e8d8a 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -885,6 +885,11 @@ config ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH config CC_HAS_INT128 def_bool !$(cc-option,$(m64-flag) -D__SIZEOF_INT128__=0) && 64BIT +config CC_IMPLICIT_FALLTHROUGH + string + default "-Wimplicit-fallthrough=5" if CC_IS_GCC + default "-Wimplicit-fallthrough" if CC_IS_CLANG && $(cc-option,-Wunreachable-code-fallthrough) + # # For architectures that know their GCC __int128 support is sound # | |