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af6bdc2a85
commit 82f2bc2fcc0160d6f82dd1ac64518ae0a4dd183f upstream.
Clang's -Wpointer-to-int-cast deviates from GCC in that it warns when
casting to enums. The kernel does this in certain places, such as device
tree matches to set the version of the device being used, which allows
the kernel to avoid using a gigantic union.
https://elixir.bootlin.com/linux/v5.5.8/source/drivers/ata/ahci_brcm.c#L428
https://elixir.bootlin.com/linux/v5.5.8/source/drivers/ata/ahci_brcm.c#L402
https://elixir.bootlin.com/linux/v5.5.8/source/include/linux/mod_devicetable.h#L264
To avoid a ton of false positive warnings, disable this particular part
of the warning, which has been split off into a separate diagnostic so
that the entire warning does not need to be turned off for clang. It
will be visible under W=1 in case people want to go about fixing these
easily and enabling the warning treewide.
Cc: stable@vger.kernel.org
Link: https://github.com/ClangBuiltLinux/linux/issues/887
Link: 2a41b31fcd
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
78 lines
2.8 KiB
Makefile
78 lines
2.8 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# ==========================================================================
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#
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# make W=... settings
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#
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# W=1 - warnings that may be relevant and does not occur too often
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# W=2 - warnings that occur quite often but may still be relevant
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# W=3 - the more obscure warnings, can most likely be ignored
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#
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# $(call cc-option, -W...) handles gcc -W.. options which
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# are not supported by all versions of the compiler
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# ==========================================================================
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KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
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ifeq ("$(origin W)", "command line")
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export KBUILD_ENABLE_EXTRA_GCC_CHECKS := $(W)
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endif
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ifdef KBUILD_ENABLE_EXTRA_GCC_CHECKS
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warning- := $(empty)
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warning-1 := -Wextra -Wunused -Wno-unused-parameter
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warning-1 += -Wmissing-declarations
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warning-1 += -Wmissing-format-attribute
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warning-1 += $(call cc-option, -Wmissing-prototypes)
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warning-1 += -Wold-style-definition
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warning-1 += $(call cc-option, -Wmissing-include-dirs)
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warning-1 += $(call cc-option, -Wunused-but-set-variable)
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warning-1 += $(call cc-option, -Wunused-const-variable)
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warning-1 += $(call cc-option, -Wpacked-not-aligned)
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warning-1 += $(call cc-disable-warning, missing-field-initializers)
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warning-1 += $(call cc-disable-warning, sign-compare)
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warning-2 := -Waggregate-return
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warning-2 += -Wcast-align
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warning-2 += -Wdisabled-optimization
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warning-2 += -Wnested-externs
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warning-2 += -Wshadow
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warning-2 += $(call cc-option, -Wlogical-op)
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warning-2 += $(call cc-option, -Wmissing-field-initializers)
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warning-2 += $(call cc-option, -Wsign-compare)
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warning-2 += $(call cc-option, -Wmaybe-uninitialized)
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warning-2 += $(call cc-option, -Wunused-macros)
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warning-3 := -Wbad-function-cast
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warning-3 += -Wcast-qual
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warning-3 += -Wconversion
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warning-3 += -Wpacked
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warning-3 += -Wpadded
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warning-3 += -Wpointer-arith
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warning-3 += -Wredundant-decls
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warning-3 += -Wswitch-default
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warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
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warning-3 += $(call cc-option, -Wvla)
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warning := $(warning-$(findstring 1, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
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warning += $(warning-$(findstring 2, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
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warning += $(warning-$(findstring 3, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
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ifeq ("$(strip $(warning))","")
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$(error W=$(KBUILD_ENABLE_EXTRA_GCC_CHECKS) is unknown)
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endif
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KBUILD_CFLAGS += $(warning)
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else
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ifeq ($(cc-name),clang)
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KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
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KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
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KBUILD_CFLAGS += $(call cc-disable-warning, format)
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KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare)
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KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length)
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KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized)
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KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
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endif
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endif
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