From: david.laight.linux@gmail.com
To: Nathan Chancellor <nathan@kernel.org>,
Arnd Bergmann <arnd@arndb.de>, Nicolas Schier <nsc@kernel.org>,
linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
Cc: David Laight <david.laight.linux@gmail.com>
Subject: [PATCH 1/1] kbuild: Only enable -Wtautological-constant-out-of-range-compare for W=2
Date: Sun, 14 Dec 2025 13:15:28 +0000 [thread overview]
Message-ID: <20251214131528.3648-1-david.laight.linux@gmail.com> (raw)
From: David Laight <david.laight.linux@gmail.com>
The kernel code style is to use !(expr) rather that (expr) == 0.
But clang complains that converting some constant expressions
(eg (0xffffu << 16)) to a boolean always evalutes to true.
This happens often in the validity checks in #defines.
Move tautological-constant-out-of-range-compare to W=2 (along with the
similar type-limits).
Signed-off-by: David Laight <david.laight.linux@gmail.com>
---
scripts/Makefile.warn | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/scripts/Makefile.warn b/scripts/Makefile.warn
index 68e6fafcb80c..e2d467835c5b 100644
--- a/scripts/Makefile.warn
+++ b/scripts/Makefile.warn
@@ -151,7 +151,6 @@ KBUILD_CFLAGS += -Wformat-insufficient-args
endif
endif
KBUILD_CFLAGS += $(call cc-option, -Wno-pointer-to-enum-cast)
-KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
KBUILD_CFLAGS += $(call cc-option, -Wno-unaligned-access)
KBUILD_CFLAGS += -Wno-enum-compare-conditional
endif
@@ -179,6 +178,7 @@ KBUILD_CFLAGS += -Wno-shift-negative-value
ifdef CONFIG_CC_IS_CLANG
KBUILD_CFLAGS += -Wno-enum-enum-conversion
+KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
endif
ifdef CONFIG_CC_IS_GCC
--
2.39.5
next reply other threads:[~2025-12-14 13:15 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-14 13:15 david.laight.linux [this message]
2025-12-19 20:12 ` [PATCH 1/1] kbuild: Only enable -Wtautological-constant-out-of-range-compare for W=2 Nathan Chancellor
2025-12-19 20:26 ` Arnd Bergmann
2025-12-19 22:18 ` David Laight
2025-12-20 10:27 ` Arnd Bergmann
2025-12-20 12:15 ` David Laight
2025-12-22 10:20 ` Arnd Bergmann
2025-12-22 17:14 ` David Laight
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