1# SPDX-License-Identifier: GPL-2.0
  2# ==========================================================================
  3# make W=... settings
  4#
  5# There are four warning groups enabled by W=1, W=2, W=3, and W=e
  6# They are independent, and can be combined like W=12 or W=123e.
  7# ==========================================================================
  8
  9KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
 10
 11# backward compatibility
 12KBUILD_EXTRA_WARN ?= $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)
 13
 14ifeq ("$(origin W)", "command line")
 15  KBUILD_EXTRA_WARN := $(W)
 16endif
 17
 18export KBUILD_EXTRA_WARN
 19
 20#
 21# W=1 - warnings which may be relevant and do not occur too often
 22#
 23ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
 24
 25KBUILD_CFLAGS += -Wextra -Wunused -Wno-unused-parameter
 26KBUILD_CFLAGS += -Wmissing-declarations
 27KBUILD_CFLAGS += -Wmissing-format-attribute
 28KBUILD_CFLAGS += -Wmissing-prototypes
 29KBUILD_CFLAGS += -Wold-style-definition
 30KBUILD_CFLAGS += -Wmissing-include-dirs
 31KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable)
 32KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
 33KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned)
 34KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
 35# The following turn off the warnings enabled by -Wextra
 36KBUILD_CFLAGS += -Wno-missing-field-initializers
 37KBUILD_CFLAGS += -Wno-sign-compare
 38KBUILD_CFLAGS += -Wno-type-limits
 39KBUILD_CFLAGS += -Wno-shift-negative-value
 40
 41KBUILD_CPPFLAGS += -Wundef
 42KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
 43
 44else
 45
 46# Some diagnostics enabled by default are noisy.
 47# Suppress them by using -Wno... except for W=1.
 48
 49ifdef CONFIG_CC_IS_CLANG
 50KBUILD_CFLAGS += -Wno-initializer-overrides
 51# Clang before clang-16 would warn on default argument promotions.
 52ifneq ($(call clang-min-version, 160000),y)
 53# Disable -Wformat
 54KBUILD_CFLAGS += -Wno-format
 55# Then re-enable flags that were part of the -Wformat group that aren't
 56# problematic.
 57KBUILD_CFLAGS += -Wformat-extra-args -Wformat-invalid-specifier
 58KBUILD_CFLAGS += -Wformat-zero-length -Wnonnull
 59# Requires clang-12+.
 60ifeq ($(call clang-min-version, 120000),y)
 61KBUILD_CFLAGS += -Wformat-insufficient-args
 62endif
 63endif
 64KBUILD_CFLAGS += -Wno-sign-compare
 65KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
 66KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
 67KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access)
 68KBUILD_CFLAGS += $(call cc-disable-warning, cast-function-type-strict)
 69endif
 70
 71endif
 72
 73#
 74# W=2 - warnings which occur quite often but may still be relevant
 75#
 76ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
 77
 78KBUILD_CFLAGS += -Wdisabled-optimization
 79KBUILD_CFLAGS += -Wshadow
 80KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
 81KBUILD_CFLAGS += -Wmissing-field-initializers
 82KBUILD_CFLAGS += -Wtype-limits
 83KBUILD_CFLAGS += $(call cc-option, -Wmaybe-uninitialized)
 84KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
 85
 86KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2
 87
 88endif
 89
 90#
 91# W=3 - more obscure warnings, can most likely be ignored
 92#
 93ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
 94
 95KBUILD_CFLAGS += -Wbad-function-cast
 96KBUILD_CFLAGS += -Wcast-align
 97KBUILD_CFLAGS += -Wcast-qual
 98KBUILD_CFLAGS += -Wconversion
 99KBUILD_CFLAGS += -Wpacked
100KBUILD_CFLAGS += -Wpadded
101KBUILD_CFLAGS += -Wpointer-arith
102KBUILD_CFLAGS += -Wredundant-decls
103KBUILD_CFLAGS += -Wsign-compare
104KBUILD_CFLAGS += -Wswitch-default
105KBUILD_CFLAGS += $(call cc-option, -Wpacked-bitfield-compat)
106
107KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
108
109endif
110
111#
112# W=e - error out on warnings
113#
114ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
115
116KBUILD_CFLAGS += -Werror
117
118endif