sh: intc: Avoid spurious sizeof-pointer-div warning

BugLink: https://bugs.launchpad.net/bugs/2023225

[ Upstream commit 2508708 ]

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
in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108483 by Jakub Jelinek

Signed-off-by: Michael Karcher <[email protected]>
Acked-by: Randy Dunlap <[email protected]> # build-tested
Link: https://lore.kernel.org/r/619fa552-c988-35e5-b1d7-fe256c46a272@mkarcher.dialup.fu-berlin.de
Signed-off-by: John Paul Adrian Glaubitz <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
Signed-off-by: Kamal Mostafa <[email protected]>
Signed-off-by: Luke Nowakowski-Krijger <[email protected]>

Author: Michael Karcher

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)	\