Re: [PATCH v3 6/6] Makefile.extrawarn: turn on missing-prototypes globally

On Thu, Nov 23, 2023 at 12:05:06PM +0100, Arnd Bergmann wrote:
> From: Arnd Bergmann <[email protected]>
> 
> Over the years we went from > 1000 of warnings to under 100 earlier
> this year, and I sent patches to address all the ones that I saw with
> compile testing randcom configs on arm64, arm and x86 kernels. This is a
> really useful warning, as it catches real bugs when there are mismatched
> prototypes. In particular with kernel control flow integrity enabled,
> those are no longer allowed.
> 
> I have done extensive testing to ensure that there are no new build
> errors or warnings on any configuration of x86, arm and arm64 builds.
> I also made sure that at least the both the normal defconfig and an
> allmodconfig build is clean for arc, csky, loongarch, m68k, microblaze,
> openrisc, parisc, powerpc, riscv, s390, and xtensa, with the respective
> maintainers doing most of the patches.
> 
> At this point, there are five architectures with a number of known
> regressions: alpha, nios2, mips, sh and sparc. In the previous version
> of this patch, I had turned off the missing prototype warnings for the 15
> architectures that still had issues, but since there are only five left,
> I think we can leave the rest to the maintainers (Cc'd here) as well.
> 

Not sure I understand why this was so important that it warrants the
resulting buildtest failures.

FWIW, I'll disable WERROR in my build tests for the affected architectures.
That is kind of counter-productive, but the only real alternative would be
to stop build (and sometimes, such as for ppc, runtime) tests entirely,
which would be even worse.

Guenter