Re: [PATCH 01/13] tools: disable -Wno-type-limits

[Rasmus Villemoes]

On 16/03/2021 02.54, Yury Norov wrote:
> GENMASK(h, l) may be passed with unsigned types. In such case, type-limits
> warning is generated for example in case of GENMASK(h, 0).
> 
> Signed-off-by: Yury Norov <yury.norov@xxxxxxxxx>
> ---
>  tools/scripts/Makefile.include | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/tools/scripts/Makefile.include b/tools/scripts/Makefile.include
> index 84dbf61a7eca..15e99905cb7d 100644
> --- a/tools/scripts/Makefile.include
> +++ b/tools/scripts/Makefile.include
> @@ -38,6 +38,7 @@ EXTRA_WARNINGS += -Wswitch-enum
>  EXTRA_WARNINGS += -Wundef
>  EXTRA_WARNINGS += -Wwrite-strings
>  EXTRA_WARNINGS += -Wformat
> +EXTRA_WARNINGS += -Wno-type-limits
>

I don't like that kind of collateral damage. I seem to recall another
instance where a macro was instead rewritten to avoid triggering the
type-limits warning (with a comment explaining the uglyness). Something like

foo > bar      is the same as
!(foo <= bar)  which is the same as
!(foo == bar || foo < bar)

Dunno if that would work here, but if it did, it would have the bonus
that when somebody builds the kernel proper with Wtype-limits enabled
(maybe W=1 or W=2) there would be no false positives from GENMASK to
wade through.

Alternatively, we really should consider making use of _Pragma to
locally disable/re-enable certain warnings.

Rasmus