Re: [PATCH] correct disabling of -Wshift-negative-value

[Nathan Chancellor <nathan@kernel.org>]

Hi Jan,

On Mon, Apr 14, 2025 at 04:23:36PM +0200, Jan Beulich wrote:
> The warning is supported only from gcc6 onwards, hence its disabling
> needs probing that the (positive) option is actually supported.
> 
> Fixes: 1344794a59db ("Kbuild: add -Wno-shift-negative-value where -Wextra is used")
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

The patch itself seems fine (I might add "scripts/Makefile.extrawarn: "
to the title) but if I understand correctly, this is only to support GCC
5? Would this be necessary if GCC 8.1 becomes the minimum supported
version of GCC for building the kernel?

https://lore.kernel.org/20250407094116.1339199-2-arnd@kernel.org/

If people are actively noticing this, perhaps we should send this to
Linus's tree for backports then Arnd could revert it in his series?

> --- a/scripts/Makefile.extrawarn
> +++ b/scripts/Makefile.extrawarn
> @@ -154,7 +154,7 @@ else
>  # The following turn off the warnings enabled by -Wextra
>  KBUILD_CFLAGS += -Wno-missing-field-initializers
>  KBUILD_CFLAGS += -Wno-type-limits
> -KBUILD_CFLAGS += -Wno-shift-negative-value
> +KBUILD_CFLAGS += $(call cc-disable-warning,shift-negative-value)
>  
>  ifdef CONFIG_CC_IS_CLANG
>  KBUILD_CFLAGS += -Wno-enum-enum-conversion

Cheers,
Nathan