From 012e33200dda70648909d3f29a0451a8c60f0dc0 Mon Sep 17 00:00:00 2001 From: "Gustavo A. R. Silva" Date: Mon, 12 Jul 2021 00:57:54 -0500 Subject: [PATCH] Makefile: Enable -Wimplicit-fallthrough for Clang With the recent fixes for fallthrough warnings, it is now possible to enable -Wimplicit-fallthrough for Clang. It's important to mention that since we have adopted the use of the pseudo-keyword macro fallthrough; we also want to avoid having more /* fall through */ comments being introduced. Notice that contrary to GCC, Clang doesn't recognize any comments as implicit fall-through markings when the -Wimplicit-fallthrough option is enabled. So, in order to avoid having more comments being introduced, we have to use the option -Wimplicit-fallthrough=5 for GCC, which similar to Clang, will cause a warning in case a code comment is intended to be used as a fall-through marking. Co-developed-by: Kees Cook Signed-off-by: Kees Cook Signed-off-by: Gustavo A. R. Silva --- Makefile | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) diff --git a/Makefile b/Makefile index c3f9bd191b894..eaa692976851a 100644 --- a/Makefile +++ b/Makefile @@ -797,12 +797,6 @@ KBUILD_CFLAGS += -Wno-gnu # source of a reference will be _MergedGlobals and not on of the whitelisted names. # See modpost pattern 2 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,) endif # These warnings generated too much noise in a regular build. @@ -983,6 +977,9 @@ NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include) # warn about C99 declaration after statement KBUILD_CFLAGS += -Wdeclaration-after-statement +# Warn about unmarked fall-throughs in switch statement. +KBUILD_CFLAGS += $(call cc-option,-Wimplicit-fallthrough=5,$(call cc-option,-Wimplicit-fallthrough,)) + # Variable Length Arrays (VLAs) should not be used anywhere in the kernel KBUILD_CFLAGS += -Wvla -- 2.39.5