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![Justin Stitt](/assets/img/avatar_default.png)
There's been an ongoing mission to re-enable the -Wformat warning for Clang. A previous attempt at enabling the warning showed that there were many instances of this warning throughout the codebase. The sheer amount of these warnings really polluted builds and thus -Wno-format was added to _temporarily_ toggle them off. After many patches the warning has largely been eradicated for x86, x86_64, arm, and arm64 on a variety of configs. The time to enable the warning has never been better as it seems for the first time we are ahead of them and can now solve them as they appear rather than tackling from a backlog. As to the root cause of this large backlog of warnings, Clang seems to pickup on some more nuanced cases of format warnings caused by implicit integer conversion as well as default argument promotions from printf-like functions. Link: https://github.com/ClangBuiltLinux/linux/issues/378 Suggested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Justin Stitt <justinstitt@google.com> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
104 lines
3 KiB
Makefile
104 lines
3 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0
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# ==========================================================================
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# make W=... settings
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#
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# There are four warning groups enabled by W=1, W=2, W=3, and W=e
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# They are independent, and can be combined like W=12 or W=123e.
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# ==========================================================================
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KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
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# backward compatibility
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KBUILD_EXTRA_WARN ?= $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)
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ifeq ("$(origin W)", "command line")
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KBUILD_EXTRA_WARN := $(W)
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endif
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export KBUILD_EXTRA_WARN
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#
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# W=1 - warnings which may be relevant and do not occur too often
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#
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ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
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KBUILD_CFLAGS += -Wextra -Wunused -Wno-unused-parameter
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KBUILD_CFLAGS += -Wmissing-declarations
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KBUILD_CFLAGS += -Wmissing-format-attribute
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KBUILD_CFLAGS += -Wmissing-prototypes
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KBUILD_CFLAGS += -Wold-style-definition
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KBUILD_CFLAGS += -Wmissing-include-dirs
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KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable)
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KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
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KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned)
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KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
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# The following turn off the warnings enabled by -Wextra
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KBUILD_CFLAGS += -Wno-missing-field-initializers
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KBUILD_CFLAGS += -Wno-sign-compare
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KBUILD_CFLAGS += -Wno-type-limits
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KBUILD_CFLAGS += -Wno-shift-negative-value
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KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
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else
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# Some diagnostics enabled by default are noisy.
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# Suppress them by using -Wno... except for W=1.
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ifdef CONFIG_CC_IS_CLANG
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KBUILD_CFLAGS += -Wno-initializer-overrides
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KBUILD_CFLAGS += -Wno-sign-compare
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KBUILD_CFLAGS += -Wno-format-zero-length
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KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
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KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
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KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access)
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endif
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endif
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#
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# W=2 - warnings which occur quite often but may still be relevant
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#
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ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
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KBUILD_CFLAGS += -Wdisabled-optimization
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KBUILD_CFLAGS += -Wshadow
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KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
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KBUILD_CFLAGS += -Wmissing-field-initializers
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KBUILD_CFLAGS += -Wtype-limits
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KBUILD_CFLAGS += $(call cc-option, -Wmaybe-uninitialized)
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KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
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KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2
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endif
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#
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# W=3 - more obscure warnings, can most likely be ignored
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#
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ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
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KBUILD_CFLAGS += -Wbad-function-cast
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KBUILD_CFLAGS += -Wcast-align
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KBUILD_CFLAGS += -Wcast-qual
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KBUILD_CFLAGS += -Wconversion
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KBUILD_CFLAGS += -Wpacked
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KBUILD_CFLAGS += -Wpadded
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KBUILD_CFLAGS += -Wpointer-arith
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KBUILD_CFLAGS += -Wredundant-decls
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KBUILD_CFLAGS += -Wsign-compare
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KBUILD_CFLAGS += -Wswitch-default
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KBUILD_CFLAGS += $(call cc-option, -Wpacked-bitfield-compat)
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KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
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endif
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#
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# W=e - error out on warnings
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#
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ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
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KBUILD_CFLAGS += -Werror
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endif
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