xref: /linux/scripts/Makefile.extrawarn (revision 88b61e3bff93f99712718db785b4aa0c1165f35c)

# SPDX-License-Identifier: GPL-2.0
# ==========================================================================
# make W=... settings
#
# There are four warning groups enabled by W=1, W=2, W=3, and W=e
# They are independent, and can be combined like W=12 or W=123e.
# ==========================================================================

KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)

# backward compatibility
KBUILD_EXTRA_WARN ?= $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)

ifeq ("$(origin W)", "command line")
  KBUILD_EXTRA_WARN := $(W)
endif

export KBUILD_EXTRA_WARN

#
# W=1 - warnings which may be relevant and do not occur too often
#
ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)

KBUILD_CFLAGS += -Wextra -Wunused -Wno-unused-parameter
KBUILD_CFLAGS += -Wmissing-declarations
KBUILD_CFLAGS += -Wmissing-format-attribute
KBUILD_CFLAGS += -Wmissing-prototypes
KBUILD_CFLAGS += -Wold-style-definition
KBUILD_CFLAGS += -Wmissing-include-dirs
KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable)
KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned)
KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
# The following turn off the warnings enabled by -Wextra
KBUILD_CFLAGS += -Wno-missing-field-initializers
KBUILD_CFLAGS += -Wno-sign-compare
KBUILD_CFLAGS += -Wno-type-limits
KBUILD_CFLAGS += -Wno-shift-negative-value

KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1

else

# Some diagnostics enabled by default are noisy.
# Suppress them by using -Wno... except for W=1.

ifdef CONFIG_CC_IS_CLANG
KBUILD_CFLAGS += -Wno-initializer-overrides
# Clang before clang-16 would warn on default argument promotions.
ifneq ($(call clang-min-version, 160000),y)
# Disable -Wformat
KBUILD_CFLAGS += -Wno-format
# Then re-enable flags that were part of the -Wformat group that aren't
# problematic.
KBUILD_CFLAGS += -Wformat-extra-args -Wformat-invalid-specifier
KBUILD_CFLAGS += -Wformat-zero-length -Wnonnull
# Requires clang-12+.
ifeq ($(call clang-min-version, 120000),y)
KBUILD_CFLAGS += -Wformat-insufficient-args
endif
endif
KBUILD_CFLAGS += -Wno-sign-compare
KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access)
endif

endif

#
# W=2 - warnings which occur quite often but may still be relevant
#
ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)

KBUILD_CFLAGS += -Wdisabled-optimization
KBUILD_CFLAGS += -Wshadow
KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
KBUILD_CFLAGS += -Wmissing-field-initializers
KBUILD_CFLAGS += -Wtype-limits
KBUILD_CFLAGS += $(call cc-option, -Wmaybe-uninitialized)
KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)

KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2

endif

#
# W=3 - more obscure warnings, can most likely be ignored
#
ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)

KBUILD_CFLAGS += -Wbad-function-cast
KBUILD_CFLAGS += -Wcast-align
KBUILD_CFLAGS += -Wcast-qual
KBUILD_CFLAGS += -Wconversion
KBUILD_CFLAGS += -Wpacked
KBUILD_CFLAGS += -Wpadded
KBUILD_CFLAGS += -Wpointer-arith
KBUILD_CFLAGS += -Wredundant-decls
KBUILD_CFLAGS += -Wsign-compare
KBUILD_CFLAGS += -Wswitch-default
KBUILD_CFLAGS += $(call cc-option, -Wpacked-bitfield-compat)

KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3

endif

#
# W=e - error out on warnings
#
ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)

KBUILD_CFLAGS += -Werror

endif