> On Thu, May 09, 2019 at 03:44:55PM +0900, Masahiro Yamada wrote: > > We do not support old Clang versions. Upgrade your clang version > > if any of these flags is unsupported. > > > > Let's add flags within ifdef CONFIG_CC_IS_CLANG unconditionally, > > except -fcatch-undefined-behavior. > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> > > --- > > > > Makefile | 10 +++++----- > > scripts/Makefile.extrawarn | 12 ++++++------ > > 2 files changed, 11 insertions(+), 11 deletions(-) > > > > diff --git a/Makefile b/Makefile > > index bd7ae11947cb..c71ffb6f55b5 100644 > > --- a/Makefile > > +++ b/Makefile > > @@ -731,15 +731,15 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong > > KBUILD_CFLAGS += $(stackp-flags-y) > > > > ifdef CONFIG_CC_IS_CLANG > > -KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) > > -KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) > > -KBUILD_CFLAGS += $(call cc-disable-warning, gnu) > > +KBUILD_CPPFLAGS += -Qunused-arguments > > +KBUILD_CFLAGS += -Wno-format-invalid-specifier > > +KBUILD_CFLAGS += -Wno-gnu > > # Quiet clang warning: comparison of unsigned expression < 0 is always false > > -KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare) > > +KBUILD_CFLAGS += -Wno-tautological-compare > > # CLANG uses a _MergedGlobals as optimization, but this breaks modpost, as the > > # source of a reference will be _MergedGlobals and not on of the whitelisted names. > > # See modpost pattern 2 > > -KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,) > > +KBUILD_CFLAGS += -mno-global-merge > > KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior) > > I think we should just remove this, I'm fairly confident the kernel > can't be reliably compiled with anything earlier than Clang 4 (Pixel 2 > was shipped with it but had some hacks, this commit is from Clang 3.5): Yeah, clang-4 is usually what I test these with, as that's the earliest known version of Clang that I ever had success with. Hopefully a lot of things will stabilize for the clang-9 release. Anyways, I checked these all w/ godbolt w/ clang-4. Tested-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > > https://github.com/llvm/llvm-project/commit/cb3f812b6b9fab8f3b41414f24e90222170417b4 > > Otherwise: > > Reviewed-by: Nathan Chancellor <natechancellor@xxxxxxxxx> > > > else > > > > diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn > > index 768306add591..523c4cafe2dc 100644 > > --- a/scripts/Makefile.extrawarn > > +++ b/scripts/Makefile.extrawarn > > @@ -66,11 +66,11 @@ KBUILD_CFLAGS += $(warning) > > else > > > > ifdef CONFIG_CC_IS_CLANG > > -KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides) > > -KBUILD_CFLAGS += $(call cc-disable-warning, unused-value) > > -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 += -Wno-initializer-overrides > > +KBUILD_CFLAGS += -Wno-unused-value > > +KBUILD_CFLAGS += -Wno-format > > +KBUILD_CFLAGS += -Wno-sign-compare > > +KBUILD_CFLAGS += -Wno-format-zero-length > > +KBUILD_CFLAGS += -Wno-uninitialized > > endif > > endif > > -- > > 2.17.1 > > -- Thanks, ~Nick Desaulniers
