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SubjectRe: [PATCH v5 1/1] arch/sh: avoid spurious sizeof-pointer-div warning
From
Hi--

On 1/24/23 13:48, Michael Karcher wrote:
> Gcc warns about the pattern sizeof(void*)/sizeof(void), as it looks like
> the abuse of a pattern to calculate the array size. This pattern appears
> in the unevaluated part of the ternary operator in _INTC_ARRAY if the
> parameter is NULL.
>
> The replacement uses an alternate approach to return 0 in case of NULL
> which does not generate the pattern sizeof(void*)/sizeof(void), but still
> emits the warning if _INTC_ARRAY is called with a nonarray parameter.
>
> This patch is required for successful compilation with -Werror enabled.
>
> The idea to use _Generic for type distinction is taken from Comment #7
> inhttps://gcc.gnu.org/bugzilla/show_bug.cgi?id=108483 by Jakub Jelinek
>
> Signed-off-by: Michael Karcher<kernel@mkarcher.dialup.fu-berlin.de>

Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested

Thanks.

> ---
> (resend of the mail as plaintext only instead of multipart/alternative)
> History:
> v5:
> - Cleanly generated the patch
> v4:
> - Put the case distinction into the numerator instead of the denominator
> - Refactor the case disctinction into a second macro
> v3:
> - I had a stern discussion with Thunderbird about not mangling the
> space characters in my email, and I hope spaces get sent as standard
> spaces now
> v2:
> - improve title and remove mostly redundant first sentence of the
> description
> - adjust formatting of the _Generic construction
>
> diff --git a/include/linux/sh_intc.h b/include/linux/sh_intc.h
> index c255273b0281..37ad81058d6a 100644
> --- a/include/linux/sh_intc.h
> +++ b/include/linux/sh_intc.h
> @@ -97,7 +97,10 @@ struct intc_hw_desc {
> unsigned int nr_subgroups;
> };
>
> -#define _INTC_ARRAY(a) a, __same_type(a, NULL) ? 0 : sizeof(a)/sizeof(*a)
> +#define _INTC_SIZEOF_OR_ZERO(a) (_Generic(a, \
> + typeof(NULL): 0, \
> + default: sizeof(a)))
> +#define _INTC_ARRAY(a) a, _INTC_SIZEOF_OR_ZERO(a)/sizeof(*a)
>
> #define INTC_HW_DESC(vectors, groups, mask_regs, \
> prio_regs, sense_regs, ack_regs) \
>
>
>

--
~Randy

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