On Tue, Sep 27, 2022 at 8:15 AM Zeng Heng <zengheng4@xxxxxxxxxx> wrote: > > Provide implicit enum-conversion warning option > in general build. When it set enabled, it can > detect implicit enum type conversion and find > potential conversion errors like below > (use "allmodconfig"): > > drivers/gpu/drm/amd/amdgpu/../display/dc/dml/dcn20/display_mode_vba_20.c:3904:46: > error: implicit conversion from ‘enum <anonymous>’ to ‘enum odm_combine_mode’ [-Werror=enum-conversion] > 3904 | locals->ODMCombineEnablePerState[i][k] = true; > | ^ > > The '-Wenum-conversion' could be regarded as > effective check on compile runtime and > call attention on potential mistakes. > > Anothor practical example could be referred to: > https://lore.kernel.org/all/CADnq5_OE0yZvEYGu82QJHL9wvVcTFZrmeTgX7URgh7FVA=jqYg@xxxxxxxxxxxxxx > > "-Wenum-conversion" was firstly introduced from > GNU gcc-10. What about clang? ;) > > Although "-Wenum-conversion" could be enabled > by "-Wextra" when compiling with 'W=1' option, > there are many warnings generated by '-Wextra' > that cause too much noise in a build. With clang, I believe that -Wenum-conversion is part of -Wall or -Wextra; so enabling this explicitly is only necessary for GCC. I wonder why it's not part of -Wall or -Wextra for GCC? Perhaps worth a bug report/feature request? > > Seeing the details from the following link: > https://gcc.gnu.org/onlinedocs/gcc-11.3.0/gcc/Warning-Options.html > > Because there are still some concerned warnings > exist, the patch marks the option disabled in default > for avoiding compile failed like using "allmodconfig". > > Signed-off-by: Zeng Heng <zengheng4@xxxxxxxxxx> > --- > Makefile | 5 +++++ > lib/Kconfig.debug | 7 +++++++ > 2 files changed, 12 insertions(+) > > diff --git a/Makefile b/Makefile > index ebd48fc956a3..1790a3624358 100644 > --- a/Makefile > +++ b/Makefile > @@ -880,6 +880,11 @@ endif > KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable) > KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable) > > +# check implicit enum conversion > +ifdef CONFIG_ENUM_CONVERSION > +KBUILD_CFLAGS += -Wenum-conversion > +endif Having a kconfig for this is overkill. cc-option with a comment about the compiler default versions is the way to go. > + > # These result in bogus false positives > KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer) > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 4f2b81229a2f..a64e06a747d8 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -417,6 +417,13 @@ config FRAME_WARN > Setting this too low will cause a lot of warnings. > Setting it to 0 disables the warning. > > +config ENUM_CONVERSION > + bool "Warn for implicit enum conversion" > + depends on GCC_VERSION >= 100300 > + default n > + help > + Tell gcc to warn at build time for implicit enum conversion. > + > config STRIP_ASM_SYMS > bool "Strip assembler-generated symbols during link" > default n > -- > 2.25.1 > -- Thanks, ~Nick Desaulniers
