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 result in bogus false positives
  41 KBUILD_CFLAGS += $(call cc-disable-warning, dangling-pointer)
  42
  43 # Variable Length Arrays (VLAs) should not be used anywhere in the kernel
  44 KBUILD_CFLAGS += -Wvla
  45
  46 # disable pointer signed / unsigned warnings in gcc 4.0
  47 KBUILD_CFLAGS += -Wno-pointer-sign
  48
  49 # In order to make sure new function cast mismatches are not introduced
  50 # in the kernel (to avoid tripping CFI checking), the kernel should be
  51 # globally built with -Wcast-function-type.
  52 KBUILD_CFLAGS += $(call cc-option, -Wcast-function-type)
  53
  54 # The allocators already balk at large sizes, so silence the compiler
  55 # warnings for bounds checks involving those possible values. While
  56 # -Wno-alloc-size-larger-than would normally be used here, earlier versions
  57 # of gcc (<9.1) weirdly don't handle the option correctly when _other_
  58 # warnings are produced (?!). Using -Walloc-size-larger-than=SIZE_MAX
  59 # doesn't work (as it is documented to), silently resolving to "0" prior to
  60 # version 9.1 (and producing an error more recently). Numeric values larger
  61 # than PTRDIFF_MAX also don't work prior to version 9.1, which are silently
  62 # ignored, continuing to default to PTRDIFF_MAX. So, left with no other
  63 # choice, we must perform a versioned check to disable this warning.
  64 # https://lore.kernel.org/lkml/20210824115859.187f272f@canb.auug.org.au
  65 KBUILD_CFLAGS-$(call gcc-min-version, 90100) += -Wno-alloc-size-larger-than
  66 KBUILD_CFLAGS += $(KBUILD_CFLAGS-y) $(CONFIG_CC_IMPLICIT_FALLTHROUGH)
  67
  68 # Prohibit date/time macros, which would make the build non-deterministic
  69 KBUILD_CFLAGS += -Werror=date-time
  70
  71 # enforce correct pointer usage
  72 KBUILD_CFLAGS += $(call cc-option,-Werror=incompatible-pointer-types)
  73
  74 # Require designated initializers for all marked structures
  75 KBUILD_CFLAGS += $(call cc-option,-Werror=designated-init)
  76
  77 # Warn if there is an enum types mismatch
  78 KBUILD_CFLAGS += $(call cc-option,-Wenum-conversion)
  79
  80 KBUILD_CFLAGS += -Wextra
  81 KBUILD_CFLAGS += -Wunused
  82
  83 #
  84 # W=1 - warnings which may be relevant and do not occur too often
  85 #
  86 ifneq ($(findstring 1, $(KBUILD_EXTRA_WARN)),)
  87
  88 KBUILD_CFLAGS += -Wmissing-format-attribute
  89 KBUILD_CFLAGS += -Wmissing-include-dirs
  90 KBUILD_CFLAGS += $(call cc-option, -Wunused-const-variable)
  91
  92 KBUILD_CPPFLAGS += -Wundef
  93 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN1
  94
  95 else
  96
  97 # Some diagnostics enabled by default are noisy.
  98 # Suppress them by using -Wno... except for W=1.
  99 KBUILD_CFLAGS += $(call cc-disable-warning, unused-but-set-variable)
 100 KBUILD_CFLAGS += $(call cc-disable-warning, unused-const-variable)
 101 KBUILD_CFLAGS += $(call cc-disable-warning, packed-not-aligned)
 102 KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow)
 103 ifdef CONFIG_CC_IS_GCC
 104 KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation)
 105 else
 106 # Clang checks for overflow/truncation with '%p', while GCC does not:
 107 # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=111219
 108 KBUILD_CFLAGS += $(call cc-disable-warning, format-overflow-non-kprintf)
 109 KBUILD_CFLAGS += $(call cc-disable-warning, format-truncation-non-kprintf)
 110 endif
 111 KBUILD_CFLAGS += $(call cc-disable-warning, stringop-truncation)
 112
 113 KBUILD_CFLAGS += -Wno-override-init # alias for -Wno-initializer-overrides in clang
 114
 115 ifdef CONFIG_CC_IS_CLANG
 116 # Clang before clang-16 would warn on default argument promotions.
 117 ifneq ($(call clang-min-version, 160000),y)
 118 # Disable -Wformat
 119 KBUILD_CFLAGS += -Wno-format
 120 # Then re-enable flags that were part of the -Wformat group that aren't
 121 # problematic.
 122 KBUILD_CFLAGS += -Wformat-extra-args -Wformat-invalid-specifier
 123 KBUILD_CFLAGS += -Wformat-zero-length -Wnonnull
 124 # Requires clang-12+.
 125 ifeq ($(call clang-min-version, 120000),y)
 126 KBUILD_CFLAGS += -Wformat-insufficient-args
 127 endif
 128 endif
 129 KBUILD_CFLAGS += $(call cc-disable-warning, pointer-to-enum-cast)
 130 KBUILD_CFLAGS += -Wno-tautological-constant-out-of-range-compare
 131 KBUILD_CFLAGS += $(call cc-disable-warning, unaligned-access)
 132 KBUILD_CFLAGS += -Wno-enum-compare-conditional
 133 KBUILD_CFLAGS += -Wno-enum-enum-conversion
 134 endif
 135
 136 endif
 137
 138 #
 139 # W=2 - warnings which occur quite often but may still be relevant
 140 #
 141 ifneq ($(findstring 2, $(KBUILD_EXTRA_WARN)),)
 142
 143 KBUILD_CFLAGS += -Wdisabled-optimization
 144 KBUILD_CFLAGS += -Wshadow
 145 KBUILD_CFLAGS += $(call cc-option, -Wlogical-op)
 146 KBUILD_CFLAGS += $(call cc-option, -Wunused-macros)
 147
 148 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN2
 149
 150 else
 151
 152 # The following turn off the warnings enabled by -Wextra
 153 KBUILD_CFLAGS += -Wno-missing-field-initializers
 154 KBUILD_CFLAGS += -Wno-type-limits
 155 KBUILD_CFLAGS += -Wno-shift-negative-value
 156
 157 ifdef CONFIG_CC_IS_GCC
 158 KBUILD_CFLAGS += -Wno-maybe-uninitialized
 159 endif
 160
 161 endif
 162
 163 #
 164 # W=3 - more obscure warnings, can most likely be ignored
 165 #
 166 ifneq ($(findstring 3, $(KBUILD_EXTRA_WARN)),)
 167
 168 KBUILD_CFLAGS += -Wbad-function-cast
 169 KBUILD_CFLAGS += -Wcast-align
 170 KBUILD_CFLAGS += -Wcast-qual
 171 KBUILD_CFLAGS += -Wconversion
 172 KBUILD_CFLAGS += -Wpacked
 173 KBUILD_CFLAGS += -Wpadded
 174 KBUILD_CFLAGS += -Wpointer-arith
 175 KBUILD_CFLAGS += -Wredundant-decls
 176 KBUILD_CFLAGS += -Wsign-compare
 177 KBUILD_CFLAGS += -Wswitch-default
 178
 179 KBUILD_CPPFLAGS += -DKBUILD_EXTRA_WARN3
 180
 181 else
 182
 183 # The following turn off the warnings enabled by -Wextra
 184 KBUILD_CFLAGS += -Wno-sign-compare
 185 KBUILD_CFLAGS += -Wno-unused-parameter
 186
 187 endif
 188
 189 #
 190 # W=e - error out on warnings
 191 #
 192 ifneq ($(findstring e, $(KBUILD_EXTRA_WARN)),)
 193
 194 KBUILD_CFLAGS += -Werror
 195
 196 endif