| Message ID | 619fa552-c988-35e5-b1d7-fe256c46a272@mkarcher.dialup.fu-berlin.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v5,1/1] arch/sh: avoid spurious sizeof-pointer-div warning | expand |
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) \ > > >
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) \
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> --- (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