m4/manywarnings.m4

   1 # manywarnings.m4 serial 21
   2 dnl Copyright (C) 2008-2021 Free Software Foundation, Inc.
   3 dnl This file is free software; the Free Software Foundation
   4 dnl gives unlimited permission to copy and/or distribute it,
   5 dnl with or without modifications, as long as this notice is preserved.
   6
   7 dnl From Simon Josefsson
   8
   9 # gl_MANYWARN_COMPLEMENT(OUTVAR, LISTVAR, REMOVEVAR)
  10 # --------------------------------------------------
  11 # Copy LISTVAR to OUTVAR except for the entries in REMOVEVAR.
  12 # Elements separated by whitespace.  In set logic terms, the function
  13 # does OUTVAR = LISTVAR \ REMOVEVAR.
  14 AC_DEFUN([gl_MANYWARN_COMPLEMENT],
  15 [
  16   gl_warn_set=
  17   set x $2; shift
  18   for gl_warn_item
  19   do
  20     case " $3 " in
  21       *" $gl_warn_item "*)
  22         ;;
  23       *)
  24         gl_AS_VAR_APPEND([gl_warn_set], [" $gl_warn_item"])
  25         ;;
  26     esac
  27   done
  28   $1=$gl_warn_set
  29 ])
  30
  31 # gl_MANYWARN_ALL_GCC(VARIABLE)
  32 # -----------------------------
  33 # Add all documented GCC warning parameters to variable VARIABLE.
  34 # Note that you need to test them using gl_WARN_ADD if you want to
  35 # make sure your gcc understands it.
  36 #
  37 # The effects of this macro depend on the current language (_AC_LANG).
  38 AC_DEFUN([gl_MANYWARN_ALL_GCC],
  39 [_AC_LANG_DISPATCH([$0], _AC_LANG, $@)])
  40
  41 # Specialization for _AC_LANG = C.
  42 AC_DEFUN([gl_MANYWARN_ALL_GCC(C)],
  43 [
  44   AC_LANG_PUSH([C])
  45
  46   dnl First, check for some issues that only occur when combining multiple
  47   dnl gcc warning categories.
  48   AC_REQUIRE([AC_PROG_CC])
  49   if test -n "$GCC"; then
  50
  51     dnl Check if -Wextra -Werror -Wno-missing-field-initializers is supported
  52     dnl with the current $CC $CFLAGS $CPPFLAGS.
  53     AC_CACHE_CHECK([whether -Wno-missing-field-initializers is supported],
  54       [gl_cv_cc_nomfi_supported],
  55       [gl_save_CFLAGS="$CFLAGS"
  56        CFLAGS="$CFLAGS -Wextra -Werror -Wno-missing-field-initializers"
  57        AC_COMPILE_IFELSE(
  58          [AC_LANG_PROGRAM([[]], [[]])],
  59          [gl_cv_cc_nomfi_supported=yes],
  60          [gl_cv_cc_nomfi_supported=no])
  61        CFLAGS="$gl_save_CFLAGS"
  62       ])
  63
  64     if test "$gl_cv_cc_nomfi_supported" = yes; then
  65       dnl Now check whether -Wno-missing-field-initializers is needed
  66       dnl for the { 0, } construct.
  67       AC_CACHE_CHECK([whether -Wno-missing-field-initializers is needed],
  68         [gl_cv_cc_nomfi_needed],
  69         [gl_save_CFLAGS="$CFLAGS"
  70          CFLAGS="$CFLAGS -Wextra -Werror"
  71          AC_COMPILE_IFELSE(
  72            [AC_LANG_PROGRAM(
  73               [[int f (void)
  74                 {
  75                   typedef struct { int a; int b; } s_t;
  76                   s_t s1 = { 0, };
  77                   return s1.b;
  78                 }
  79               ]],
  80               [[]])],
  81            [gl_cv_cc_nomfi_needed=no],
  82            [gl_cv_cc_nomfi_needed=yes])
  83          CFLAGS="$gl_save_CFLAGS"
  84         ])
  85     fi
  86
  87     dnl Next, check if -Werror -Wuninitialized is useful with the
  88     dnl user's choice of $CFLAGS; some versions of gcc warn that it
  89     dnl has no effect if -O is not also used
  90     AC_CACHE_CHECK([whether -Wuninitialized is supported],
  91       [gl_cv_cc_uninitialized_supported],
  92       [gl_save_CFLAGS="$CFLAGS"
  93        CFLAGS="$CFLAGS -Werror -Wuninitialized"
  94        AC_COMPILE_IFELSE(
  95          [AC_LANG_PROGRAM([[]], [[]])],
  96          [gl_cv_cc_uninitialized_supported=yes],
  97          [gl_cv_cc_uninitialized_supported=no])
  98        CFLAGS="$gl_save_CFLAGS"
  99       ])
 100
 101   fi
 102
 103   # List all gcc warning categories.
 104   # To compare this list to your installed GCC's, run this Bash command:
 105   #
 106   # comm -3 \
 107   #  <((sed -n 's/^  *\(-[^ 0-9][^ ]*\).*/\1/p' manywarnings.m4; \
 108   #     awk '/^[^#]/ {print $1}' ../build-aux/gcc-warning.spec) | sort) \
 109   #  <(LC_ALL=C gcc --help=warnings | sed -n 's/^  \(-[^ ]*\) .*/\1/p' | sort)
 110
 111   $1=
 112   for gl_manywarn_item in -fanalyzer -fno-common \
 113     -Wall \
 114     -Warith-conversion \
 115     -Wbad-function-cast \
 116     -Wcast-align=strict \
 117     -Wdate-time \
 118     -Wdisabled-optimization \
 119     -Wdouble-promotion \
 120     -Wduplicated-branches \
 121     -Wduplicated-cond \
 122     -Wextra \
 123     -Wformat-signedness \
 124     -Winit-self \
 125     -Winline \
 126     -Winvalid-pch \
 127     -Wlogical-op \
 128     -Wmissing-declarations \
 129     -Wmissing-include-dirs \
 130     -Wmissing-prototypes \
 131     -Wnested-externs \
 132     -Wnull-dereference \
 133     -Wold-style-definition \
 134     -Wopenmp-simd \
 135     -Woverlength-strings \
 136     -Wpacked \
 137     -Wpointer-arith \
 138     -Wshadow \
 139     -Wstack-protector \
 140     -Wstrict-overflow \
 141     -Wstrict-prototypes \
 142     -Wsuggest-attribute=cold \
 143     -Wsuggest-attribute=const \
 144     -Wsuggest-attribute=format \
 145     -Wsuggest-attribute=malloc \
 146     -Wsuggest-attribute=noreturn \
 147     -Wsuggest-attribute=pure \
 148     -Wsuggest-final-methods \
 149     -Wsuggest-final-types \
 150     -Wsync-nand \
 151     -Wsystem-headers \
 152     -Wtrampolines \
 153     -Wuninitialized \
 154     -Wunknown-pragmas \
 155     -Wunsafe-loop-optimizations \
 156     -Wunused-macros \
 157     -Wvariadic-macros \
 158     -Wvector-operation-performance \
 159     -Wvla \
 160     -Wwrite-strings \
 161     \
 162     ; do
 163     gl_AS_VAR_APPEND([$1], [" $gl_manywarn_item"])
 164   done
 165
 166   # gcc --help=warnings outputs an unusual form for these options; list
 167   # them here so that the above 'comm' command doesn't report a false match.
 168   gl_AS_VAR_APPEND([$1], [' -Warray-bounds=2'])
 169   gl_AS_VAR_APPEND([$1], [' -Wattribute-alias=2'])
 170   gl_AS_VAR_APPEND([$1], [' -Wformat-overflow=2'])
 171   gl_AS_VAR_APPEND([$1], [' -Wformat=2'])
 172   gl_AS_VAR_APPEND([$1], [' -Wformat-truncation=2'])
 173   gl_AS_VAR_APPEND([$1], [' -Wimplicit-fallthrough=5'])
 174   gl_AS_VAR_APPEND([$1], [' -Wshift-overflow=2'])
 175   gl_AS_VAR_APPEND([$1], [' -Wunused-const-variable=2'])
 176   gl_AS_VAR_APPEND([$1], [' -Wvla-larger-than=4031'])
 177
 178   # These are needed for older GCC versions.
 179   if test -n "$GCC"; then
 180     case `($CC --version) 2>/dev/null` in
 181       'gcc (GCC) '[[0-3]].* | \
 182       'gcc (GCC) '4.[[0-7]].*)
 183         gl_AS_VAR_APPEND([$1], [' -fdiagnostics-show-option'])
 184         gl_AS_VAR_APPEND([$1], [' -funit-at-a-time'])
 185           ;;
 186     esac
 187   fi
 188
 189   # Disable specific options as needed.
 190   if test "$gl_cv_cc_nomfi_needed" = yes; then
 191     gl_AS_VAR_APPEND([$1], [' -Wno-missing-field-initializers'])
 192   fi
 193
 194   if test "$gl_cv_cc_uninitialized_supported" = no; then
 195     gl_AS_VAR_APPEND([$1], [' -Wno-uninitialized'])
 196   fi
 197
 198   # Some warnings have too many false alarms in GCC 10.1.
 199   # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93695
 200   gl_AS_VAR_APPEND([$1], [' -Wno-analyzer-double-free'])
 201   # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94458
 202   gl_AS_VAR_APPEND([$1], [' -Wno-analyzer-malloc-leak'])
 203   # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94851
 204   gl_AS_VAR_APPEND([$1], [' -Wno-analyzer-null-dereference'])
 205   # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95758
 206   gl_AS_VAR_APPEND([$1], [' -Wno-analyzer-use-after-free'])
 207
 208   AC_LANG_POP([C])
 209 ])
 210
 211 # Specialization for _AC_LANG = C++.
 212 AC_DEFUN([gl_MANYWARN_ALL_GCC(C++)],
 213 [
 214   gl_MANYWARN_ALL_GCC_CXX_IMPL([$1])
 215 ])