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Message-ID: <68e5d3d1-7d7d-232c-c6dc-3f65bfb55114@mkarcher.dialup.fu-berlin.de>
Date: Mon, 23 Jan 2023 19:45:19 +0100
From: Michael Karcher <kernel@...rcher.dialup.fu-berlin.de>
To: linux-kernel@...r.kernel.org, linux-sh@...r.kernel.org,
Segher Boessenkool <segher@...nel.crashing.org>,
Rich Felker <dalias@...c.org>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>,
John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>
Subject: [PATCH v3 1/1] arch/sh: avoid spurious sizeof-pointer-div warning
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>
---
History:
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..98d1da0d8e36 100644
--- a/include/linux/sh_intc.h
+++ b/include/linux/sh_intc.h
@@ -97,7 +97,9 @@ 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) \
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