Re: [PATCH v3 1/2] kbuild: refactor scripts/Makefile.extrawarn

[Nathan Chancellor]

On Wed, Sep 04, 2019 at 11:46:45PM +0200, Arnd Bergmann wrote:
> On Sat, Aug 31, 2019 at 6:26 PM Masahiro Yamada
> <yamada.masahiro@xxxxxxxxxxxxx> wrote:
> 
> > +# Some diagnostics enabled by default are noisy.
> > +# Suppress them by using -Wno... except for W=1.
> > +
> >  ifdef CONFIG_CC_IS_CLANG
> >  KBUILD_CFLAGS += -Wno-initializer-overrides
> >  KBUILD_CFLAGS += -Wno-format
> >  KBUILD_CFLAGS += -Wno-sign-compare
> >  KBUILD_CFLAGS += -Wno-format-zero-length
> >  endif
> 
> FWIW, I just found out I missed a bug that clang failed to warn about
> because of the  -Wno-format. Apparently gcc warns only about type
> mismatches that result in incompatible calling conventions (e.g.
> int vs int64_t) but not smaller types (int, short) that get converted to an
> int anyway. Passing -Wno-format turns both off.
> 
>       Arnd

Hi Arnd,

This has been fixed in clang 10.0.0 but this areas has not been updated
as nobody has sent a patch yet:

https://github.com/ClangBuiltLinux/linux/issues/378#issuecomment-524411147

Cheers,
Nathan