1 dnl Macros to check the presence of generic (non-typed) symbols. 2 dnl Copyright (c) 2006-2008 Diego Petten <flameeyes gmail com> 3 dnl Copyright (c) 2006-2008 xine project 4 dnl Copyright (c) 2021 libuv project 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 3, 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 the flag is supported by compiler 37 dnl CC_CHECK_CFLAGS_SILENT([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND]) 38 39 AC_DEFUN([CC_CHECK_CFLAGS_SILENT], [ 40 AC_CACHE_VAL(AS_TR_SH([cc_cv_cflags_$1]), 41 [ac_save_CFLAGS="$CFLAGS" 42 CFLAGS="$CFLAGS $1" 43 AC_COMPILE_IFELSE([AC_LANG_SOURCE([int a;])], 44 [eval "AS_TR_SH([cc_cv_cflags_$1])='yes'"], 45 [eval "AS_TR_SH([cc_cv_cflags_$1])='no'"]) 46 CFLAGS="$ac_save_CFLAGS" 47 ]) 48 49 AS_IF([eval test x$]AS_TR_SH([cc_cv_cflags_$1])[ = xyes], 50 [$2], [$3]) 51 ]) 52 53 dnl Check if the flag is supported by compiler (cacheable) 54 dnl CC_CHECK_CFLAGS([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND]) 55 56 AC_DEFUN([CC_CHECK_CFLAGS], [ 57 AC_CACHE_CHECK([if $CC supports $1 flag], 58 AS_TR_SH([cc_cv_cflags_$1]), 59 CC_CHECK_CFLAGS_SILENT([$1]) dnl Don't execute actions here! 60 ) 61 62 AS_IF([eval test x$]AS_TR_SH([cc_cv_cflags_$1])[ = xyes], 63 [$2], [$3]) 64 ]) 65 66 dnl CC_CHECK_CFLAG_APPEND(FLAG, [action-if-found], [action-if-not-found]) 67 dnl Check for CFLAG and appends them to AM_CFLAGS if supported 68 AC_DEFUN([CC_CHECK_CFLAG_APPEND], [ 69 AC_CACHE_CHECK([if $CC supports $1 flag], 70 AS_TR_SH([cc_cv_cflags_$1]), 71 CC_CHECK_CFLAGS_SILENT([$1]) dnl Don't execute actions here! 72 ) 73 74 AS_IF([eval test x$]AS_TR_SH([cc_cv_cflags_$1])[ = xyes], 75 [AM_CFLAGS="$AM_CFLAGS $1"; DEBUG_CFLAGS="$DEBUG_CFLAGS $1"; $2], [$3]) 76 77 AC_SUBST([AM_CFLAGS]) 78 ]) 79 80 dnl CC_CHECK_CFLAGS_APPEND([FLAG1 FLAG2], [action-if-found], [action-if-not]) 81 AC_DEFUN([CC_CHECK_CFLAGS_APPEND], [ 82 for flag in $1; do 83 CC_CHECK_CFLAG_APPEND($flag, [$2], [$3]) 84 done 85 ]) 86 87 dnl Check if the flag is supported by linker (cacheable) 88 dnl CC_CHECK_LDFLAGS([FLAG], [ACTION-IF-FOUND],[ACTION-IF-NOT-FOUND]) 89 90 AC_DEFUN([CC_CHECK_LDFLAGS], [ 91 AC_CACHE_CHECK([if $CC supports $1 flag], 92 AS_TR_SH([cc_cv_ldflags_$1]), 93 [ac_save_LDFLAGS="$LDFLAGS" 94 LDFLAGS="$LDFLAGS $1" 95 AC_LANG_PUSH([C]) 96 AC_LINK_IFELSE([AC_LANG_SOURCE([int main() { return 1; }])], 97 [eval "AS_TR_SH([cc_cv_ldflags_$1])='yes'"], 98 [eval "AS_TR_SH([cc_cv_ldflags_$1])="]) 99 AC_LANG_POP([C]) 100 LDFLAGS="$ac_save_LDFLAGS" 101 ]) 102 103 AS_IF([eval test x$]AS_TR_SH([cc_cv_ldflags_$1])[ = xyes], 104 [$2], [$3]) 105 ]) 106 107 dnl Check if flag is supported by both compiler and linker 108 dnl If so, append it to AM_CFLAGS 109 dnl CC_CHECK_FLAG_SUPPORTED_APPEND([FLAG]) 110 111 AC_DEFUN([CC_CHECK_FLAG_SUPPORTED_APPEND], [ 112 CC_CHECK_CFLAGS([$1], 113 [CC_CHECK_LDFLAGS([$1], 114 [AM_CFLAGS="$AM_CFLAGS $1"; 115 DEBUG_CFLAGS="$DEBUG_CFLAGS $1"; 116 AC_SUBST([AM_CFLAGS]) 117 ]) 118 ]) 119 ]) 120 121 dnl define the LDFLAGS_NOUNDEFINED variable with the correct value for 122 dnl the current linker to avoid undefined references in a shared object. 123 AC_DEFUN([CC_NOUNDEFINED], [ 124 dnl We check $host for which systems to enable this for. 125 AC_REQUIRE([AC_CANONICAL_HOST]) 126 127 case $host in 128 dnl FreeBSD (et al.) does not complete linking for shared objects when pthreads 129 dnl are requested, as different implementations are present; to avoid problems 130 dnl use -Wl,-z,defs only for those platform not behaving this way. 131 *-freebsd* | *-openbsd*) ;; 132 *) 133 dnl First of all check for the --no-undefined variant of GNU ld. This allows 134 dnl for a much more readable commandline, so that people can understand what 135 dnl it does without going to look for what the heck -z defs does. 136 for possible_flags in "-Wl,--no-undefined" "-Wl,-z,defs"; do 137 CC_CHECK_LDFLAGS([$possible_flags], [LDFLAGS_NOUNDEFINED="$possible_flags"]) 138 break 139 done 140 ;; 141 esac 142 143 AC_SUBST([LDFLAGS_NOUNDEFINED]) 144 ]) 145 146 dnl Check for a -Werror flag or equivalent. -Werror is the GCC 147 dnl and ICC flag that tells the compiler to treat all the warnings 148 dnl as fatal. We usually need this option to make sure that some 149 dnl constructs (like attributes) are not simply ignored. 150 dnl 151 dnl Other compilers don't support -Werror per se, but they support 152 dnl an equivalent flag: 153 dnl - Sun Studio compiler supports -errwarn=%all 154 AC_DEFUN([CC_CHECK_WERROR], [ 155 AC_CACHE_CHECK( 156 [for $CC way to treat warnings as errors], 157 [cc_cv_werror], 158 [CC_CHECK_CFLAGS_SILENT([-Werror], [cc_cv_werror=-Werror], 159 [CC_CHECK_CFLAGS_SILENT([-errwarn=%all], [cc_cv_werror=-errwarn=%all])]) 160 ]) 161 ]) 162 163 AC_DEFUN([CC_CHECK_ATTRIBUTE], [ 164 AC_REQUIRE([CC_CHECK_WERROR]) 165 AC_CACHE_CHECK([if $CC supports __attribute__(( ifelse([$2], , [$1], [$2]) ))], 166 AS_TR_SH([cc_cv_attribute_$1]), 167 [ac_save_CFLAGS="$CFLAGS" 168 CFLAGS="$CFLAGS $cc_cv_werror" 169 AC_LANG_PUSH([C]) 170 AC_COMPILE_IFELSE([AC_LANG_SOURCE([$3])], 171 [eval "AS_TR_SH([cc_cv_attribute_$1])='yes'"], 172 [eval "AS_TR_SH([cc_cv_attribute_$1])='no'"]) 173 AC_LANG_POP([C]) 174 CFLAGS="$ac_save_CFLAGS" 175 ]) 176 177 AS_IF([eval test x$]AS_TR_SH([cc_cv_attribute_$1])[ = xyes], 178 [AC_DEFINE( 179 AS_TR_CPP([SUPPORT_ATTRIBUTE_$1]), 1, 180 [Define this if the compiler supports __attribute__(( ifelse([$2], , [$1], [$2]) ))] 181 ) 182 $4], 183 [$5]) 184 ]) 185 186 AC_DEFUN([CC_ATTRIBUTE_CONSTRUCTOR], [ 187 CC_CHECK_ATTRIBUTE( 188 [constructor],, 189 [void __attribute__((constructor)) ctor() { int a; }], 190 [$1], [$2]) 191 ]) 192 193 AC_DEFUN([CC_ATTRIBUTE_FORMAT], [ 194 CC_CHECK_ATTRIBUTE( 195 [format], [format(printf, n, n)], 196 [void __attribute__((format(printf, 1, 2))) printflike(const char *fmt, ...) { fmt = (void *)0; }], 197 [$1], [$2]) 198 ]) 199 200 AC_DEFUN([CC_ATTRIBUTE_FORMAT_ARG], [ 201 CC_CHECK_ATTRIBUTE( 202 [format_arg], [format_arg(printf)], 203 [char *__attribute__((format_arg(1))) gettextlike(const char *fmt) { fmt = (void *)0; }], 204 [$1], [$2]) 205 ]) 206 207 AC_DEFUN([CC_ATTRIBUTE_VISIBILITY], [ 208 CC_CHECK_ATTRIBUTE( 209 [visibility_$1], [visibility("$1")], 210 [void __attribute__((visibility("$1"))) $1_function() { }], 211 [$2], [$3]) 212 ]) 213 214 AC_DEFUN([CC_ATTRIBUTE_NONNULL], [ 215 CC_CHECK_ATTRIBUTE( 216 [nonnull], [nonnull()], 217 [void __attribute__((nonnull())) some_function(void *foo, void *bar) { foo = (void*)0; bar = (void*)0; }], 218 [$1], [$2]) 219 ]) 220 221 AC_DEFUN([CC_ATTRIBUTE_UNUSED], [ 222 CC_CHECK_ATTRIBUTE( 223 [unused], , 224 [void some_function(void *foo, __attribute__((unused)) void *bar);], 225 [$1], [$2]) 226 ]) 227 228 AC_DEFUN([CC_ATTRIBUTE_SENTINEL], [ 229 CC_CHECK_ATTRIBUTE( 230 [sentinel], , 231 [void some_function(void *foo, ...) __attribute__((sentinel));], 232 [$1], [$2]) 233 ]) 234 235 AC_DEFUN([CC_ATTRIBUTE_DEPRECATED], [ 236 CC_CHECK_ATTRIBUTE( 237 [deprecated], , 238 [void some_function(void *foo, ...) __attribute__((deprecated));], 239 [$1], [$2]) 240 ]) 241 242 AC_DEFUN([CC_ATTRIBUTE_ALIAS], [ 243 CC_CHECK_ATTRIBUTE( 244 [alias], [weak, alias], 245 [void other_function(void *foo) { } 246 void some_function(void *foo) __attribute__((weak, alias("other_function")));], 247 [$1], [$2]) 248 ]) 249 250 AC_DEFUN([CC_ATTRIBUTE_MALLOC], [ 251 CC_CHECK_ATTRIBUTE( 252 [malloc], , 253 [void * __attribute__((malloc)) my_alloc(int n);], 254 [$1], [$2]) 255 ]) 256 257 AC_DEFUN([CC_ATTRIBUTE_PACKED], [ 258 CC_CHECK_ATTRIBUTE( 259 [packed], , 260 [struct astructure { char a; int b; long c; void *d; } __attribute__((packed));], 261 [$1], [$2]) 262 ]) 263 264 AC_DEFUN([CC_ATTRIBUTE_CONST], [ 265 CC_CHECK_ATTRIBUTE( 266 [const], , 267 [int __attribute__((const)) twopow(int n) { return 1 << n; } ], 268 [$1], [$2]) 269 ]) 270 271 AC_DEFUN([CC_FLAG_VISIBILITY], [ 272 AC_REQUIRE([CC_CHECK_WERROR]) 273 AC_CACHE_CHECK([if $CC supports -fvisibility=hidden], 274 [cc_cv_flag_visibility], 275 [cc_flag_visibility_save_CFLAGS="$CFLAGS" 276 CFLAGS="$CFLAGS $cc_cv_werror" 277 CC_CHECK_CFLAGS_SILENT([-fvisibility=hidden], 278 cc_cv_flag_visibility='yes', 279 cc_cv_flag_visibility='no') 280 CFLAGS="$cc_flag_visibility_save_CFLAGS"]) 281 282 AS_IF([test "x$cc_cv_flag_visibility" = "xyes"], 283 [AC_DEFINE([SUPPORT_FLAG_VISIBILITY], 1, 284 [Define this if the compiler supports the -fvisibility flag]) 285 $1], 286 [$2]) 287 ]) 288 289 AC_DEFUN([CC_FUNC_EXPECT], [ 290 AC_REQUIRE([CC_CHECK_WERROR]) 291 AC_CACHE_CHECK([if compiler has __builtin_expect function], 292 [cc_cv_func_expect], 293 [ac_save_CFLAGS="$CFLAGS" 294 CFLAGS="$CFLAGS $cc_cv_werror" 295 AC_LANG_PUSH([C]) 296 AC_COMPILE_IFELSE([AC_LANG_SOURCE( 297 [int some_function() { 298 int a = 3; 299 return (int)__builtin_expect(a, 3); 300 }])], 301 [cc_cv_func_expect=yes], 302 [cc_cv_func_expect=no]) 303 AC_LANG_POP([C]) 304 CFLAGS="$ac_save_CFLAGS" 305 ]) 306 307 AS_IF([test "x$cc_cv_func_expect" = "xyes"], 308 [AC_DEFINE([SUPPORT__BUILTIN_EXPECT], 1, 309 [Define this if the compiler supports __builtin_expect() function]) 310 $1], 311 [$2]) 312 ]) 313 314 AC_DEFUN([CC_ATTRIBUTE_ALIGNED], [ 315 AC_REQUIRE([CC_CHECK_WERROR]) 316 AC_CACHE_CHECK([highest __attribute__ ((aligned ())) supported], 317 [cc_cv_attribute_aligned], 318 [ac_save_CFLAGS="$CFLAGS" 319 CFLAGS="$CFLAGS $cc_cv_werror" 320 AC_LANG_PUSH([C]) 321 for cc_attribute_align_try in 64 32 16 8 4 2; do 322 AC_COMPILE_IFELSE([AC_LANG_SOURCE([ 323 int main() { 324 static char c __attribute__ ((aligned($cc_attribute_align_try))) = 0; 325 return c; 326 }])], [cc_cv_attribute_aligned=$cc_attribute_align_try; break]) 327 done 328 AC_LANG_POP([C]) 329 CFLAGS="$ac_save_CFLAGS" 330 ]) 331 332 if test "x$cc_cv_attribute_aligned" != "x"; then 333 AC_DEFINE_UNQUOTED([ATTRIBUTE_ALIGNED_MAX], [$cc_cv_attribute_aligned], 334 [Define the highest alignment supported]) 335 fi 336 ]) 337
Indexes created Wed Apr 22 00:22:44 UTC 2026