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scripts/Makefile.extrawarn: Do not show clang's non-kprintf warnings at W=1

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Clang's -Wformat-overflow and -Wformat-truncation have chosen to check
'%p' unlike GCC but it does not know about the kernel's pointer
extensions in lib/vsprintf.c, so the developers split that part of the
warning out for the kernel to disable because there will always be false
positives.

Commit 908dd50827 ("kbuild: enable -Wformat-truncation on clang") did
disabled these warnings but only in a block that would be called when
W=1 was not passed, so they would appear with W=1. Move the disabling of
the non-kprintf warnings to a block that always runs so that they are
never seen, regardless of warning level.

Fixes: 908dd50827 ("kbuild: enable -Wformat-truncation on clang")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202501291646.VtwF98qd-lkp@intel.com/
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
This commit is contained in:
Nathan Chancellor 2025-01-31 15:55:28 -07:00 • committed by Masahiro Yamada
parent 2014c95afe
commit 738fc998b6
1 changed files with 5 additions and 5 deletions
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10
scripts/Makefile.extrawarn
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@ -31,6 +31,11 @@ KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
ifdef CONFIG_CC_IS_CLANG
# The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
KBUILD_CFLAGS += -Wno-gnu
# Clang checks for overflow/truncation with '%p', while GCC does not:
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111219
KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow-non-kprintf)
KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation-non-kprintf)
else
# gcc inanely warns about local variables called 'main'
@ -105,11 +110,6 @@ KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
ifdef CONFIG_CC_IS_GCC
KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
else
# Clang checks for overflow/truncation with '%p', while GCC does not:
# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111219
KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow-non-kprintf)
KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation-non-kprintf)
endif
KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)