| Message ID | 20230811140327.3754597-6-arnd@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Kbuild: warning options cleanup and more warnings | expand |
On Sat, Aug 12, 2023 at 10:50 AM Arnd Bergmann <arnd@kernel.org> wrote: > > From: Arnd Bergmann <arnd@arndb.de> > > The stringop and format warnings got disabled globally when they were > newly introduced in commit bd664f6b3e376 ("disable new gcc-7.1.1 warnings > for now"), 217c3e0196758 ("disable stringop truncation warnings for now") > and 5a76021c2eff7 ("gcc-10: disable 'stringop-overflow' warning for now"). > > In all cases, the sentiment at the time was that the warnings are > useful, and we actually addressed a number of real bugs based on > them, but we never managed to eliminate them all because even the > build bots using W=1 builds only see the -Wstringop-truncation > warnings that are enabled at that level. > > Move these into the W=1 section to give them a larger build coverage > and actually eliminate them over time. > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > --- > scripts/Makefile.extrawarn | 11 ++++++----- > 1 file changed, 6 insertions(+), 5 deletions(-) > > diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn > index 87bfe153198f1..ec528972371fa 100644 > --- a/scripts/Makefile.extrawarn > +++ b/scripts/Makefile.extrawarn > @@ -16,8 +16,6 @@ KBUILD_CFLAGS += -Werror=strict-prototypes > KBUILD_CFLAGS += -Wno-format-security > KBUILD_CFLAGS += -Wno-trigraphs > KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,) > -KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation) > -KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow) > KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member) > > ifneq ($(CONFIG_FRAME_WARN),0) > @@ -56,9 +54,6 @@ KBUILD_CFLAGS += -Wno-pointer-sign > # globally built with -Wcast-function-type. > KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type) > > -# We'll want to enable this eventually, but it's not going away for 5.7 at least > -KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow) > - > # Another good warning that we'll want to enable eventually > KBUILD_CFLAGS += $(call cc-disable-warning, restrict) > > @@ -111,6 +106,9 @@ KBUILD_CFLAGS += -Wmissing-include-dirs > KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable) > KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable) > KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned) > +KBUILD_CFLAGS += $(call cc-option, -Wformat-overflow) > +KBUILD_CFLAGS += $(call cc-option, -Wformat-truncation) These are redundant because -Wall implies -Wformat-overflow and -Wformat-truncation according to the GCC manual.
On Sat, Aug 12, 2023 at 10:10 PM Masahiro Yamada <masahiroy@kernel.org> wrote: > > On Sat, Aug 12, 2023 at 10:50 AM Arnd Bergmann <arnd@kernel.org> wrote: > > > > From: Arnd Bergmann <arnd@arndb.de> > > > > The stringop and format warnings got disabled globally when they were > > newly introduced in commit bd664f6b3e376 ("disable new gcc-7.1.1 warnings > > for now"), 217c3e0196758 ("disable stringop truncation warnings for now") > > and 5a76021c2eff7 ("gcc-10: disable 'stringop-overflow' warning for now"). > > > > In all cases, the sentiment at the time was that the warnings are > > useful, and we actually addressed a number of real bugs based on > > them, but we never managed to eliminate them all because even the > > build bots using W=1 builds only see the -Wstringop-truncation > > warnings that are enabled at that level. > > > > Move these into the W=1 section to give them a larger build coverage > > and actually eliminate them over time. > > > > Signed-off-by: Arnd Bergmann <arnd@arndb.de> > > --- > > scripts/Makefile.extrawarn | 11 ++++++----- > > 1 file changed, 6 insertions(+), 5 deletions(-) > > > > diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn > > index 87bfe153198f1..ec528972371fa 100644 > > --- a/scripts/Makefile.extrawarn > > +++ b/scripts/Makefile.extrawarn > > @@ -16,8 +16,6 @@ KBUILD_CFLAGS += -Werror=strict-prototypes > > KBUILD_CFLAGS += -Wno-format-security > > KBUILD_CFLAGS += -Wno-trigraphs > > KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,) > > -KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation) > > -KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow) > > KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member) > > > > ifneq ($(CONFIG_FRAME_WARN),0) > > @@ -56,9 +54,6 @@ KBUILD_CFLAGS += -Wno-pointer-sign > > # globally built with -Wcast-function-type. > > KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type) > > > > -# We'll want to enable this eventually, but it's not going away for 5.7 at least > > -KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow) > > - > > # Another good warning that we'll want to enable eventually > > KBUILD_CFLAGS += $(call cc-disable-warning, restrict) > > > > @@ -111,6 +106,9 @@ KBUILD_CFLAGS += -Wmissing-include-dirs > > KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable) > > KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable) > > KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned) > > +KBUILD_CFLAGS += $(call cc-option, -Wformat-overflow) > > +KBUILD_CFLAGS += $(call cc-option, -Wformat-truncation) > > > These are redundant because -Wall implies > -Wformat-overflow and -Wformat-truncation > according to the GCC manual. > > > > > -- > Best Regards > Masahiro Yamada Applied to linux-kbuild. Thanks.
On Sat, Aug 12, 2023 at 6:11 AM Masahiro Yamada <masahiroy@kernel.org> wrote: > > These are redundant because -Wall implies > -Wformat-overflow and -Wformat-truncation > according to the GCC manual. To triple check this grouping behavior in clang, there's a utility called `diagtool`. $ diagtool tree will print the hierarchy of diagnostics and color code them to explain whether they're on/off by default or not-implemented-but-recognized. For the above two -Wformat-* warnings, note that clang does not yet implement those. I've filed https://github.com/llvm/llvm-project/issues/64871 to track that.
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn index 87bfe153198f1..ec528972371fa 100644 --- a/scripts/Makefile.extrawarn +++ b/scripts/Makefile.extrawarn @@ -16,8 +16,6 @@ KBUILD_CFLAGS += -Werror=strict-prototypes KBUILD_CFLAGS += -Wno-format-security KBUILD_CFLAGS += -Wno-trigraphs KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,) -KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation) -KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow) KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member) ifneq ($(CONFIG_FRAME_WARN),0) @@ -56,9 +54,6 @@ KBUILD_CFLAGS += -Wno-pointer-sign # globally built with -Wcast-function-type. KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type) -# We'll want to enable this eventually, but it's not going away for 5.7 at least -KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow) - # Another good warning that we'll want to enable eventually KBUILD_CFLAGS += $(call cc-disable-warning, restrict) @@ -111,6 +106,9 @@ KBUILD_CFLAGS += -Wmissing-include-dirs KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable) KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable) KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned) +KBUILD_CFLAGS += $(call cc-option, -Wformat-overflow) +KBUILD_CFLAGS += $(call cc-option, -Wformat-truncation) +KBUILD_CFLAGS += $(call cc-option, -Wstringop-overflow) KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation) KBUILD_CPPFLAGS += -Wundef @@ -123,6 +121,9 @@ else KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable) KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable) KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned) +KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow) +KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation) +KBUILD_CFLAGS += $(call cc-disable-warning, stringop-overflow) KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation) ifdef CONFIG_CC_IS_CLANG