linux-kernel - [PATCH AUTOSEL 6.2 11/13] sh: intc: Avoid spurious sizeof-pointer-div warning

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Date:   Tue, 14 Mar 2023 08:43:03 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>,
        Randy Dunlap <rdunlap@...radead.org>,
        John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH AUTOSEL 6.2 11/13] sh: intc: Avoid spurious sizeof-pointer-div warning

From: Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>

[ Upstream commit 250870824c1cf199b032b1ef889c8e8d69d9123a ]

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 <kernel@...rcher.dialup.fu-berlin.de>
Acked-by: Randy Dunlap <rdunlap@...radead.org> # 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 <glaubitz@...sik.fu-berlin.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/linux/sh_intc.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/linux/sh_intc.h b/include/linux/sh_intc.h
index c255273b02810..37ad81058d6ae 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)	\
-- 
2.39.2