m4/attributes.m4

   1 dnl Macros to check the presence of generic (non-typed) symbols.
   2 dnl Copyright (c) 2006-2008 Diego Pettenò <flameeyes@gmail.com>
   3 dnl Copyright (c) 2006-2008 xine project
   4 dnl Copyright (c) 2012 Lucas De Marchi <lucas.de.marchi@gmail.com>
   5 dnl
   6 dnl This program is free software; you can redistribute it and/or modify
   7 dnl it under the terms of the GNU General Public License as published by
   8 dnl the Free Software Foundation; either version 2, or (at your option)
   9 dnl any later version.
  10 dnl
  11 dnl This program is distributed in the hope that it will be useful,
  12 dnl but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 dnl MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 dnl GNU General Public License for more details.
  15 dnl
  16 dnl You should have received a copy of the GNU General Public License
  17 dnl along with this program; if not, write to the Free Software
  18 dnl Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 dnl 02110-1301, USA.
  20 dnl
  21 dnl As a special exception, the copyright owners of the
  22 dnl macro gives unlimited permission to copy, distribute and modify the
  23 dnl configure scripts that are the output of Autoconf when processing the
  24 dnl Macro. You need not follow the terms of the GNU General Public
  25 dnl License when using or distributing such scripts, even though portions
  26 dnl of the text of the Macro appear in them. The GNU General Public
  27 dnl License (GPL) does govern all other use of the material that
  28 dnl constitutes the Autoconf Macro.
  29 dnl
  30 dnl This special exception to the GPL applies to versions of the
  31 dnl Autoconf Macro released by this project. When you make and
  32 dnl distribute a modified version of the Autoconf Macro, you may extend
  33 dnl this special exception to the GPL to apply to your modified version as
  34 dnl well.
  35
  36 dnl Check if FLAG in ENV-VAR is supported by compiler and append it
  37 dnl to WHERE-TO-APPEND variable. Note that we invert -Wno-* checks to
  38 dnl -W* as gcc cannot test for negated warnings.
  39 dnl CC_CHECK_FLAG_APPEND([WHERE-TO-APPEND], [ENV-VAR], [FLAG])
  40
  41 AC_DEFUN([CC_CHECK_FLAG_APPEND], [
  42   AC_CACHE_CHECK([if $CC supports flag $3 in envvar $2],
  43                  AS_TR_SH([cc_cv_$2_$3]),
  44           [eval "AS_TR_SH([cc_save_$2])='${$2}'"
  45            eval "AS_TR_SH([$2])='-Werror `echo "$3" | sed 's/^-Wno-/-W/'`'"
  46            AC_LINK_IFELSE([AC_LANG_SOURCE([int main(void) { return 0; } ])],
  47                           [eval "AS_TR_SH([cc_cv_$2_$3])='yes'"],
  48                           [eval "AS_TR_SH([cc_cv_$2_$3])='no'"])
  49            eval "AS_TR_SH([$2])='$cc_save_$2'"])
  50
  51   AS_IF([eval test x$]AS_TR_SH([cc_cv_$2_$3])[ = xyes],
  52         [eval "$1='${$1} $3'"])
  53 ])
  54
  55 dnl CC_CHECK_FLAGS_APPEND([WHERE-TO-APPEND], [ENV-VAR], [FLAG1 FLAG2])
  56 AC_DEFUN([CC_CHECK_FLAGS_APPEND], [
  57   for flag in $3; do
  58     CC_CHECK_FLAG_APPEND($1, $2, $flag)
  59   done
  60 ])
  61
  62 dnl Check if the flag is supported by linker (cacheable)
  63 dnl CC_CHECK_LDFLAGS([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND])
  64
  65 AC_DEFUN([CC_CHECK_LDFLAGS], [
  66   AC_CACHE_CHECK([if $CC supports $1 flag],
  67     AS_TR_SH([cc_cv_ldflags_$1]),
  68     [ac_save_LDFLAGS="$LDFLAGS"
  69      LDFLAGS="$LDFLAGS $1"
  70      AC_LINK_IFELSE([int main() { return 1; }],
  71        [eval "AS_TR_SH([cc_cv_ldflags_$1])='yes'"],
  72        [eval "AS_TR_SH([cc_cv_ldflags_$1])="])
  73      LDFLAGS="$ac_save_LDFLAGS"
  74     ])
  75
  76   AS_IF([eval test x$]AS_TR_SH([cc_cv_ldflags_$1])[ = xyes],
  77     [$2], [$3])
  78 ])
  79
  80 dnl define the LDFLAGS_NOUNDEFINED variable with the correct value for
  81 dnl the current linker to avoid undefined references in a shared object.
  82 AC_DEFUN([CC_NOUNDEFINED], [
  83   dnl We check $host for which systems to enable this for.
  84   AC_REQUIRE([AC_CANONICAL_HOST])
  85
  86   case $host in
  87      dnl FreeBSD (et al.) does not complete linking for shared objects when pthreads
  88      dnl are requested, as different implementations are present; to avoid problems
  89      dnl use -Wl,-z,defs only for those platform not behaving this way.
  90      *-freebsd* | *-openbsd*) ;;
  91      *)
  92         dnl First of all check for the --no-undefined variant of GNU ld. This allows
  93         dnl for a much more readable command line, so that people can understand what
  94         dnl it does without going to look for what the heck -z defs does.
  95         for possible_flags in "-Wl,--no-undefined" "-Wl,-z,defs"; do
  96            CC_CHECK_LDFLAGS([$possible_flags], [LDFLAGS_NOUNDEFINED="$possible_flags"])
  97            break
  98         done
  99      ;;
 100   esac
 101
 102   AC_SUBST([LDFLAGS_NOUNDEFINED])
 103 ])
 104
 105 dnl Check for a -Werror flag or equivalent. -Werror is the GCC
 106 dnl and ICC flag that tells the compiler to treat all the warnings
 107 dnl as fatal. We usually need this option to make sure that some
 108 dnl constructs (like attributes) are not simply ignored.
 109 dnl
 110 dnl Other compilers don't support -Werror per se, but they support
 111 dnl an equivalent flag:
 112 dnl  - Sun Studio compiler supports -errwarn=%all
 113 AC_DEFUN([CC_CHECK_WERROR], [
 114   AC_CACHE_CHECK(
 115     [for $CC way to treat warnings as errors],
 116     [cc_cv_werror],
 117     [CC_CHECK_CFLAGS_SILENT([-Werror], [cc_cv_werror=-Werror],
 118       [CC_CHECK_CFLAGS_SILENT([-errwarn=%all], [cc_cv_werror=-errwarn=%all])])
 119     ])
 120 ])
 121
 122 AC_DEFUN([CC_CHECK_ATTRIBUTE], [
 123   AC_REQUIRE([CC_CHECK_WERROR])
 124   AC_CACHE_CHECK([if $CC supports __attribute__(( ifelse([$2], , [$1], [$2]) ))],
 125     AS_TR_SH([cc_cv_attribute_$1]),
 126     [ac_save_CFLAGS="$CFLAGS"
 127      CFLAGS="$CFLAGS $cc_cv_werror"
 128      AC_COMPILE_IFELSE([AC_LANG_SOURCE([$3])],
 129        [eval "AS_TR_SH([cc_cv_attribute_$1])='yes'"],
 130        [eval "AS_TR_SH([cc_cv_attribute_$1])='no'"])
 131      CFLAGS="$ac_save_CFLAGS"
 132     ])
 133
 134   AS_IF([eval test x$]AS_TR_SH([cc_cv_attribute_$1])[ = xyes],
 135     [AC_DEFINE(
 136        AS_TR_CPP([SUPPORT_ATTRIBUTE_$1]), 1,
 137          [Define this if the compiler supports __attribute__(( ifelse([$2], , [$1], [$2]) ))]
 138          )
 139      $4],
 140     [$5])
 141 ])
 142
 143 AC_DEFUN([CC_ATTRIBUTE_CONSTRUCTOR], [
 144   CC_CHECK_ATTRIBUTE(
 145     [constructor],,
 146     [void __attribute__((constructor)) ctor() { int a; }],
 147     [$1], [$2])
 148 ])
 149
 150 AC_DEFUN([CC_ATTRIBUTE_FORMAT], [
 151   CC_CHECK_ATTRIBUTE(
 152     [format], [format(printf, n, n)],
 153     [void __attribute__((format(printf, 1, 2))) printflike(const char *fmt, ...) { fmt = (void *)0; }],
 154     [$1], [$2])
 155 ])
 156
 157 AC_DEFUN([CC_ATTRIBUTE_FORMAT_ARG], [
 158   CC_CHECK_ATTRIBUTE(
 159     [format_arg], [format_arg(printf)],
 160     [char *__attribute__((format_arg(1))) gettextlike(const char *fmt) { fmt = (void *)0; }],
 161     [$1], [$2])
 162 ])
 163
 164 AC_DEFUN([CC_ATTRIBUTE_VISIBILITY], [
 165   CC_CHECK_ATTRIBUTE(
 166     [visibility_$1], [visibility("$1")],
 167     [void __attribute__((visibility("$1"))) $1_function() { }],
 168     [$2], [$3])
 169 ])
 170
 171 AC_DEFUN([CC_ATTRIBUTE_NONNULL], [
 172   CC_CHECK_ATTRIBUTE(
 173     [nonnull], [nonnull()],
 174     [void __attribute__((nonnull())) some_function(void *foo, void *bar) { foo = (void*)0; bar = (void*)0; }],
 175     [$1], [$2])
 176 ])
 177
 178 AC_DEFUN([CC_ATTRIBUTE_UNUSED], [
 179   CC_CHECK_ATTRIBUTE(
 180     [unused], ,
 181     [void some_function(void *foo, __attribute__((unused)) void *bar);],
 182     [$1], [$2])
 183 ])
 184
 185 AC_DEFUN([CC_ATTRIBUTE_SENTINEL], [
 186   CC_CHECK_ATTRIBUTE(
 187     [sentinel], ,
 188     [void some_function(void *foo, ...) __attribute__((sentinel));],
 189     [$1], [$2])
 190 ])
 191
 192 AC_DEFUN([CC_ATTRIBUTE_DEPRECATED], [
 193   CC_CHECK_ATTRIBUTE(
 194     [deprecated], ,
 195     [void some_function(void *foo, ...) __attribute__((deprecated));],
 196     [$1], [$2])
 197 ])
 198
 199 AC_DEFUN([CC_ATTRIBUTE_ALIAS], [
 200   CC_CHECK_ATTRIBUTE(
 201     [alias], [weak, alias],
 202     [void other_function(void *foo) { }
 203      void some_function(void *foo) __attribute__((weak, alias("other_function")));],
 204     [$1], [$2])
 205 ])
 206
 207 AC_DEFUN([CC_ATTRIBUTE_MALLOC], [
 208   CC_CHECK_ATTRIBUTE(
 209     [malloc], ,
 210     [void * __attribute__((malloc)) my_alloc(int n);],
 211     [$1], [$2])
 212 ])
 213
 214 AC_DEFUN([CC_ATTRIBUTE_PACKED], [
 215   CC_CHECK_ATTRIBUTE(
 216     [packed], ,
 217     [struct astructure { char a; int b; long c; void *d; } __attribute__((packed));],
 218     [$1], [$2])
 219 ])
 220
 221 AC_DEFUN([CC_ATTRIBUTE_CONST], [
 222   CC_CHECK_ATTRIBUTE(
 223     [const], ,
 224     [int __attribute__((const)) twopow(int n) { return 1 << n; } ],
 225     [$1], [$2])
 226 ])
 227
 228 AC_DEFUN([CC_FLAG_VISIBILITY], [
 229   AC_REQUIRE([CC_CHECK_WERROR])
 230   AC_CACHE_CHECK([if $CC supports -fvisibility=hidden],
 231     [cc_cv_flag_visibility],
 232     [cc_flag_visibility_save_CFLAGS="$CFLAGS"
 233      CFLAGS="$CFLAGS $cc_cv_werror"
 234      CC_CHECK_CFLAGS_SILENT([-fvisibility=hidden],
 235      cc_cv_flag_visibility='yes',
 236      cc_cv_flag_visibility='no')
 237      CFLAGS="$cc_flag_visibility_save_CFLAGS"])
 238
 239   AS_IF([test "x$cc_cv_flag_visibility" = "xyes"],
 240     [AC_DEFINE([SUPPORT_FLAG_VISIBILITY], 1,
 241        [Define this if the compiler supports the -fvisibility flag])
 242      $1],
 243     [$2])
 244 ])
 245
 246 AC_DEFUN([CC_FUNC_EXPECT], [
 247   AC_REQUIRE([CC_CHECK_WERROR])
 248   AC_CACHE_CHECK([if compiler has __builtin_expect function],
 249     [cc_cv_func_expect],
 250     [ac_save_CFLAGS="$CFLAGS"
 251      CFLAGS="$CFLAGS $cc_cv_werror"
 252      AC_COMPILE_IFELSE([AC_LANG_SOURCE(
 253        [int some_function() {
 254         int a = 3;
 255         return (int)__builtin_expect(a, 3);
 256      }])],
 257        [cc_cv_func_expect=yes],
 258        [cc_cv_func_expect=no])
 259      CFLAGS="$ac_save_CFLAGS"
 260     ])
 261
 262   AS_IF([test "x$cc_cv_func_expect" = "xyes"],
 263     [AC_DEFINE([SUPPORT__BUILTIN_EXPECT], 1,
 264      [Define this if the compiler supports __builtin_expect() function])
 265      $1],
 266     [$2])
 267 ])
 268
 269 AC_DEFUN([CC_ATTRIBUTE_ALIGNED], [
 270   AC_REQUIRE([CC_CHECK_WERROR])
 271   AC_CACHE_CHECK([highest __attribute__ ((aligned ())) supported],
 272     [cc_cv_attribute_aligned],
 273     [ac_save_CFLAGS="$CFLAGS"
 274      CFLAGS="$CFLAGS $cc_cv_werror"
 275      for cc_attribute_align_try in 64 32 16 8 4 2; do
 276         AC_COMPILE_IFELSE([AC_LANG_SOURCE([
 277           int main() {
 278             static char c __attribute__ ((aligned($cc_attribute_align_try))) = 0;
 279             return c;
 280           }])], [cc_cv_attribute_aligned=$cc_attribute_align_try; break])
 281      done
 282      CFLAGS="$ac_save_CFLAGS"
 283   ])
 284
 285   if test "x$cc_cv_attribute_aligned" != "x"; then
 286      AC_DEFINE_UNQUOTED([ATTRIBUTE_ALIGNED_MAX], [$cc_cv_attribute_aligned],
 287        [Define the highest alignment supported])
 288   fi
 289 ])