scripts/Makefile.extrawarn

   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
   9 # Default set of warnings, always enabled
  10 KBUILD_CFLAGS += -Wall
  11 KBUILD_CFLAGS += -Wundef
  12 KBUILD_CFLAGS += -Werror=implicit-function-declaration
  13 KBUILD_CFLAGS += -Werror=implicit-int
  14 KBUILD_CFLAGS += -Werror=return-type
  15 KBUILD_CFLAGS += -Werror=strict-prototypes
  16 KBUILD_CFLAGS += -Wno-format-security
  17 KBUILD_CFLAGS += -Wno-trigraphs
  18 KBUILD_CFLAGS += $(call cc-disable-warning,frame-address,)
  19 KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member)
  20 KBUILD_CFLAGS += -Wmissing-declarations
  21 KBUILD_CFLAGS += -Wmissing-prototypes
  22
  23 ifneq ($(CONFIG_FRAME_WARN),0)
  24 KBUILD_CFLAGS += -Wframe-larger-than=$(CONFIG_FRAME_WARN)
  25 endif
  26
  27 KBUILD_CPPFLAGS-$(CONFIG_WERROR) += -Werror
  28 KBUILD_CPPFLAGS += $(KBUILD_CPPFLAGS-y)
  29 KBUILD_CFLAGS-$(CONFIG_CC_NO_ARRAY_BOUNDS) += -Wno-array-bounds
  30
  31 ifdef CONFIG_CC_IS_CLANG
  32 # The kernel builds with '-std=gnu11' so use of GNU extensions is acceptable.
  33 KBUILD_CFLAGS += -Wno-gnu
  34 else
  35
  36 # gcc inanely warns about local variables called 'main'
  37 KBUILD_CFLAGS += -Wno-main
  38 endif
  39
  40 # These warnings generated too much noise in a regular build.
  41 # Use make W=1 to enable them (see scripts/Makefile.extrawarn)
  42 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
  43 KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
  44
  45 # These result in bogus false positives
  46 KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer)
  47
  48 # Variable Length Arrays (VLAs) should not be used anywhere in the kernel
  49 KBUILD_CFLAGS += -Wvla
  50
  51 # disable pointer signed / unsigned warnings in gcc 4.0
  52 KBUILD_CFLAGS += -Wno-pointer-sign
  53
  54 # In order to make sure new function cast mismatches are not introduced
  55 # in the kernel (to avoid tripping CFI checking), the kernel should be
  56 # globally built with -Wcast-function-type.
  57 KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
  58
  59 # The allocators already balk at large sizes, so silence the compiler
  60 # warnings for bounds checks involving those possible values. While
  61 # -Wno-alloc-size-larger-than would normally be used here, earlier versions
  62 # of gcc (<9.1) weirdly don't handle the option correctly when _other_
  63 # warnings are produced (?!). Using -Walloc-size-larger-than=SIZE_MAX
  64 # doesn't work (as it is documented to), silently resolving to "0" prior to
  65 # version 9.1 (and producing an error more recently). Numeric values larger
  66 # than PTRDIFF_MAX also don't work prior to version 9.1, which are silently
  67 # ignored, continuing to default to PTRDIFF_MAX. So, left with no other
  68 # choice, we must perform a versioned check to disable this warning.
  69 # https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au
  70 KBUILD_CFLAGS-$(call gcc-min-version, 90100) += -Wno-alloc-size-larger-than
  71 KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
  72
  73 # Prohibit date/time macros, which would make the build non-deterministic
  74 KBUILD_CFLAGS += -Werror=date-time
  75
  76 # enforce correct pointer usage
  77 KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
  78
  79 # Require designated initializers for all marked structures
  80 KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
  81
  82 # Warn if there is an enum types mismatch
  83 KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion)
  84
  85 #
  86 # W=1 - warnings which may be relevant and do not occur too often
  87 #
  88 ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
  89
  90 KBUILD_CFLAGS += -Wextra -Wunused -Wno-unused-parameter
  91 KBUILD_CFLAGS += $(call cc-option, -Wrestrict)
  92 KBUILD_CFLAGS += -Wmissing-format-attribute
  93 KBUILD_CFLAGS += -Wold-style-definition
  94 KBUILD_CFLAGS += -Wmissing-include-dirs
  95 KBUILD_CFLAGS += $(call cc-option, -Wunused-but-set-variable)
  96 KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
  97 KBUILD_CFLAGS += $(call cc-option, -Wpacked-not-aligned)
  98 KBUILD_CFLAGS += $(call cc-option, -Wformat-overflow)
  99 KBUILD_CFLAGS += $(call cc-option, -Wformat-truncation)
 100 KBUILD_CFLAGS += $(call cc-option, -Wstringop-truncation)
 101
 102 KBUILD_CPPFLAGS += -Wundef
 103 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
 104
 105 else
 106
 107 # Some diagnostics enabled by default are noisy.
 108 # Suppress them by using -Wno... except for W=1.
 109 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
 110 KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
 111 KBUILD_CFLAGS += $(call cc-disable-warning, restrict)
 112 KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
 113 KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
 114 KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
 115 KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
 116
 117 ifdef CONFIG_CC_IS_CLANG
 118 # Clang before clang-16 would warn on default argument promotions.
 119 ifneq ($(call clang-min-version, 160000),y)
 120 # Disable -Wformat
 121 KBUILD_CFLAGS += -Wno-format
 122 # Then re-enable flags that were part of the -Wformat group that aren't
 123 # problematic.
 124 KBUILD_CFLAGS += -Wformat-extra-args -Wformat-invalid-specifier
 125 KBUILD_CFLAGS += -Wformat-zero-length -Wnonnull
 126 # Requires clang-12+.
 127 ifeq ($(call clang-min-version, 120000),y)
 128 KBUILD_CFLAGS += -Wformat-insufficient-args
 129 endif
 130 endif
 131 KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
 132 KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
 133 KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access)
 134 KBUILD_CFLAGS += $(call cc-disable-warning, cast-function-type-strict)
 135 KBUILD_CFLAGS += -Wno-enum-compare-conditional
 136 KBUILD_CFLAGS += -Wno-enum-enum-conversion
 137 endif
 138
 139 endif
 140
 141 #
 142 # W=2 - warnings which occur quite often but may still be relevant
 143 #
 144 ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
 145
 146 KBUILD_CFLAGS += -Wdisabled-optimization
 147 KBUILD_CFLAGS += -Wshadow
 148 KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
 149 KBUILD_CFLAGS += -Wmissing-field-initializers
 150 KBUILD_CFLAGS += -Wtype-limits
 151 KBUILD_CFLAGS += $(call cc-option, -Wmaybe-uninitialized)
 152 KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
 153
 154 ifdef CONFIG_CC_IS_CLANG
 155 KBUILD_CFLAGS += -Winitializer-overrides
 156 endif
 157
 158 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2
 159
 160 else
 161
 162 # The following turn off the warnings enabled by -Wextra
 163 KBUILD_CFLAGS += -Wno-missing-field-initializers
 164 KBUILD_CFLAGS += -Wno-type-limits
 165 KBUILD_CFLAGS += -Wno-shift-negative-value
 166
 167 ifdef CONFIG_CC_IS_CLANG
 168 KBUILD_CFLAGS += -Wno-initializer-overrides
 169 else
 170 KBUILD_CFLAGS += -Wno-maybe-uninitialized
 171 endif
 172
 173 endif
 174
 175 #
 176 # W=3 - more obscure warnings, can most likely be ignored
 177 #
 178 ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
 179
 180 KBUILD_CFLAGS += -Wbad-function-cast
 181 KBUILD_CFLAGS += -Wcast-align
 182 KBUILD_CFLAGS += -Wcast-qual
 183 KBUILD_CFLAGS += -Wconversion
 184 KBUILD_CFLAGS += -Wpacked
 185 KBUILD_CFLAGS += -Wpadded
 186 KBUILD_CFLAGS += -Wpointer-arith
 187 KBUILD_CFLAGS += -Wredundant-decls
 188 KBUILD_CFLAGS += -Wsign-compare
 189 KBUILD_CFLAGS += -Wswitch-default
 190
 191 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
 192
 193 else
 194
 195 # The following turn off the warnings enabled by -Wextra
 196 KBUILD_CFLAGS += -Wno-sign-compare
 197
 198 endif
 199
 200 #
 201 # W=e - error out on warnings
 202 #
 203 ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
 204
 205 KBUILD_CFLAGS += -Werror
 206
 207 endif