On Mon, Aug 19, 2019 at 3:43 AM Nathan Chancellor <natechancellor@xxxxxxxxx> wrote: > > On Mon, Aug 19, 2019 at 01:43:08AM +0900, Masahiro Yamada wrote: > > Hi. > > > > On Fri, Aug 16, 2019 at 7:59 AM Nathan Huckleberry <nhuck@xxxxxxxxxx> wrote: > > > > > > Clang is updating to support -Wimplicit-fallthrough on C > > > https://reviews.llvm.org/D64838. Since clang does not > > > support the comment version of fallthrough annotations > > > this update causes an additional 50k warnings. Most > > > of these warnings (>49k) are duplicates from header files. > > > > > > This patch is intended to be reverted after the warnings > > > have been cleaned up. > > > > > > Signed-off-by: Nathan Huckleberry <nhuck@xxxxxxxxxx> > > > Suggested-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > > > Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > > > --- > > > Changes v1->v2 > > > * Move code to preexisting ifdef > > > scripts/Makefile.extrawarn | 1 + > > > 1 file changed, 1 insertion(+) > > > > > > diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn > > > index a74ce2e3c33e..95973a1ee999 100644 > > > --- a/scripts/Makefile.extrawarn > > > +++ b/scripts/Makefile.extrawarn > > > @@ -70,5 +70,6 @@ KBUILD_CFLAGS += -Wno-initializer-overrides > > > KBUILD_CFLAGS += -Wno-format > > > KBUILD_CFLAGS += -Wno-sign-compare > > > KBUILD_CFLAGS += -Wno-format-zero-length > > > +KBUILD_CFLAGS += $(call cc-option,-Wno-implicit-fallthrough) > > > endif > > > endif > > > -- > > > 2.23.0.rc1.153.gdeed80330f-goog > > > > > > > > > Perhaps, is the following even cleaner? > > > > > > > > diff --git a/Makefile b/Makefile > > index 1b23f95db176..cebc6bf5372e 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -751,6 +751,9 @@ else > > # These warnings generated too much noise in a regular build. > > # Use make W=1 to enable them (see scripts/Makefile.extrawarn) > > KBUILD_CFLAGS += -Wno-unused-but-set-variable > > + > > +# Warn about unmarked fall-throughs in switch statement. > > +KBUILD_CFLAGS += $(call cc-option,-Wimplicit-fallthrough,) > > endif > > > > KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable) > > @@ -845,9 +848,6 @@ 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,) > > - > > # Variable Length Arrays (VLAs) should not be used anywhere in the kernel > > KBUILD_CFLAGS += -Wvla > > > > > > > > -- > > Best Regards > > Masahiro Yamada > > I like this more than anything suggested so far. I think a comment > should be added regarding why this is only enabled for GCC right now but > that is pretty easy to revert once we have figured out the right course > of action. Agree. This is well-explained in the commit log, but adding a short comment will be nice. BTW, I personally like the traditional comment version of fallthrough annotations. Is there a plan for Clang to support it as well as the attribute? Thanks. -- Best Regards Masahiro Yamada
