libbacktrace/configure.ac

   1 # configure.ac -- Backtrace configure script.
   2 # Copyright (C) 2012-2018 Free Software Foundation, Inc.
   3
   4 # Redistribution and use in source and binary forms, with or without
   5 # modification, are permitted provided that the following conditions are
   6 # met:
   7
   8 #     (1) Redistributions of source code must retain the above copyright
   9 #     notice, this list of conditions and the following disclaimer.
  10
  11 #     (2) Redistributions in binary form must reproduce the above copyright
  12 #     notice, this list of conditions and the following disclaimer in
  13 #     the documentation and/or other materials provided with the
  14 #     distribution.
  15
  16 #     (3) The name of the author may not be used to
  17 #     endorse or promote products derived from this software without
  18 #     specific prior written permission.
  19
  20 # THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  21 # IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  22 # WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  23 # DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
  24 # INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  25 # (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  26 # SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  27 # HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  28 # STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  29 # IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  30 # POSSIBILITY OF SUCH DAMAGE.
  31
  32 AC_PREREQ(2.64)
  33 AC_INIT(package-unused, version-unused,, libbacktrace)
  34 AC_CONFIG_SRCDIR(backtrace.h)
  35 AC_CONFIG_HEADER(config.h)
  36
  37 if test -n "${with_target_subdir}"; then
  38   AM_ENABLE_MULTILIB(, ..)
  39 fi
  40
  41 AC_CANONICAL_SYSTEM
  42 target_alias=${target_alias-$host_alias}
  43
  44 AC_USE_SYSTEM_EXTENSIONS
  45
  46 libtool_VERSION=1:0:0
  47 AC_SUBST(libtool_VERSION)
  48
  49 # 1.11.1: Require that version of automake.
  50 # foreign: Don't require README, INSTALL, NEWS, etc.
  51 # no-define: Don't define PACKAGE and VERSION.
  52 # no-dependencies: Don't generate automatic dependencies.
  53 #    (because it breaks when using bootstrap-lean, since some of the
  54 #    headers are gone at "make install" time).
  55 # -Wall: Issue all automake warnings.
  56 # -Wno-portability: Don't warn about constructs supported by GNU make.
  57 #    (because GCC requires GNU make anyhow).
  58 AM_INIT_AUTOMAKE([1.11.1 foreign no-dist no-define no-dependencies -Wall -Wno-portability])
  59
  60 AM_MAINTAINER_MODE
  61
  62 AC_ARG_WITH(target-subdir,
  63 [  --with-target-subdir=SUBDIR      Configuring in a subdirectory for target])
  64
  65 # We must force CC to /not/ be precious variables; otherwise
  66 # the wrong, non-multilib-adjusted value will be used in multilibs.
  67 # As a side effect, we have to subst CFLAGS ourselves.
  68 m4_rename([_AC_ARG_VAR_PRECIOUS],[backtrace_PRECIOUS])
  69 m4_define([_AC_ARG_VAR_PRECIOUS],[])
  70 AC_PROG_CC
  71 m4_rename_force([backtrace_PRECIOUS],[_AC_ARG_VAR_PRECIOUS])
  72
  73 AC_SUBST(CFLAGS)
  74
  75 AC_PROG_RANLIB
  76
  77 AC_PROG_AWK
  78 case "$AWK" in
  79 "") AC_MSG_ERROR([can't build without awk]) ;;
  80 esac
  81
  82 LT_INIT
  83 AM_PROG_LIBTOOL
  84
  85 AC_SYS_LARGEFILE
  86
  87 backtrace_supported=yes
  88
  89 if test -n "${with_target_subdir}"; then
  90   # We are compiling a GCC library.  We can assume that the unwind
  91   # library exists.
  92   BACKTRACE_FILE="backtrace.lo simple.lo"
  93 else
  94   AC_CHECK_HEADER([unwind.h],
  95     [AC_CHECK_FUNC([_Unwind_Backtrace],
  96                    [BACKTRACE_FILE="backtrace.lo simple.lo"],
  97                    [BACKTRACE_FILE="nounwind.lo"
  98                     backtrace_supported=no])],
  99     [BACKTRACE_FILE="nounwind.lo"
 100      backtrace_supported=no])
 101 fi
 102 AC_SUBST(BACKTRACE_FILE)
 103
 104 EXTRA_FLAGS=
 105 if test -n "${with_target_subdir}"; then
 106   EXTRA_FLAGS="-funwind-tables -frandom-seed=\$@"
 107 else
 108   AC_CACHE_CHECK([for -funwind-tables option],
 109     [libbacktrace_cv_c_unwind_tables],
 110     [CFLAGS_hold="$CFLAGS"
 111      CFLAGS="$CFLAGS -funwind-tables"
 112      AC_COMPILE_IFELSE(
 113        [AC_LANG_PROGRAM([static int f() { return 0; }], [return f();])],
 114        [libbacktrace_cv_c_unwind_tables=yes],
 115        [libbacktrace_cv_c_unwind_tables=no])
 116      CFLAGS="$CFLAGS_hold"])
 117   if test "$libbacktrace_cv_c_unwind_tables" = "yes"; then
 118     EXTRA_FLAGS=-funwind-tables
 119   fi
 120   AC_CACHE_CHECK([for -frandom-seed=string option],
 121     [libbacktrace_cv_c_random_seed_string],
 122     [CFLAGS_hold="$CFLAGS"
 123      CFLAGS="$CFLAGS -frandom-seed=conftest.lo"
 124      AC_COMPILE_IFELSE(
 125        [AC_LANG_PROGRAM([], [return 0;])],
 126        [libbacktrace_cv_c_random_seed_string=yes],
 127        [libbacktrace_cv_c_random_seed_string=no])
 128      CFLAGS="$CFLAGS_hold"])
 129   if test "$libbacktrace_cv_c_random_seed_string" = "yes"; then
 130     EXTRA_FLAGS="$EXTRA_FLAGS -frandom-seed=\$@"
 131   fi
 132 fi
 133
 134 if test -n "${with_target_subdir}"; then
 135   # Add CET specific flags is Intel CET is enabled.
 136   GCC_CET_FLAGS(CET_FLAGS)
 137   EXTRA_FLAGS="$EXTRA_FLAGS $CET_FLAGS"
 138 fi
 139 AC_SUBST(EXTRA_FLAGS)
 140
 141 ACX_PROG_CC_WARNING_OPTS([-W -Wall -Wwrite-strings -Wstrict-prototypes \
 142                           -Wmissing-prototypes -Wold-style-definition \
 143                           -Wmissing-format-attribute -Wcast-qual],
 144                           [WARN_FLAGS])
 145
 146 if test -n "${with_target_subdir}"; then
 147   WARN_FLAGS="$WARN_FLAGS -Werror"
 148 fi
 149
 150 AC_SUBST(WARN_FLAGS)
 151
 152 if test -n "${with_target_subdir}"; then
 153   GCC_CHECK_UNWIND_GETIPINFO
 154 else
 155   ac_save_CFFLAGS="$CFLAGS"
 156   CFLAGS="$CFLAGS -Werror-implicit-function-declaration"
 157   AC_MSG_CHECKING([for _Unwind_GetIPInfo])
 158   AC_LINK_IFELSE(
 159     [AC_LANG_PROGRAM(
 160        [#include "unwind.h"
 161         struct _Unwind_Context *context;
 162         int ip_before_insn = 0;],
 163         [return _Unwind_GetIPInfo (context, &ip_before_insn);])],
 164         [have_unwind_getipinfo=yes], [have_unwind_getipinfo=no])
 165   CFLAGS="$ac_save_CFLAGS"
 166   AC_MSG_RESULT([$have_unwind_getipinfo])
 167   if test "$have_unwind_getipinfo" = "yes"; then
 168     AC_DEFINE(HAVE_GETIPINFO, 1, [Define if _Unwind_GetIPInfo is available.])
 169   fi
 170 fi
 171
 172 # Enable --enable-host-shared.
 173 AC_ARG_ENABLE(host-shared,
 174 [AS_HELP_STRING([--enable-host-shared],
 175                 [build host code as shared libraries])],
 176 [PIC_FLAG=-fPIC], [PIC_FLAG=])
 177 AC_SUBST(PIC_FLAG)
 178
 179 # Test for __sync support.
 180 AC_CACHE_CHECK([__sync extensions],
 181 [libbacktrace_cv_sys_sync],
 182 [if test -n "${with_target_subdir}"; then
 183    case "${host}" in
 184    hppa*-*-hpux*) libbacktrace_cv_sys_sync=no ;;
 185    *) libbacktrace_cv_sys_sync=yes ;;
 186    esac
 187  else
 188    AC_LINK_IFELSE(
 189      [AC_LANG_PROGRAM([int i;],
 190                       [__sync_bool_compare_and_swap (&i, i, i);
 191                        __sync_lock_test_and_set (&i, 1);
 192                        __sync_lock_release (&i);])],
 193      [libbacktrace_cv_sys_sync=yes],
 194      [libbacktrace_cv_sys_sync=no])
 195  fi])
 196 BACKTRACE_SUPPORTS_THREADS=0
 197 if test "$libbacktrace_cv_sys_sync" = "yes"; then
 198   BACKTRACE_SUPPORTS_THREADS=1
 199   AC_DEFINE([HAVE_SYNC_FUNCTIONS], 1,
 200             [Define to 1 if you have the __sync functions])
 201 fi
 202 AC_SUBST(BACKTRACE_SUPPORTS_THREADS)
 203
 204 # Test for __atomic support.
 205 AC_CACHE_CHECK([__atomic extensions],
 206 [libbacktrace_cv_sys_atomic],
 207 [if test -n "${with_target_subdir}"; then
 208    libbacktrace_cv_sys_atomic=yes
 209  else
 210    AC_LINK_IFELSE(
 211      [AC_LANG_PROGRAM([int i;],
 212                       [__atomic_load_n (&i, __ATOMIC_ACQUIRE);
 213                        __atomic_store_n (&i, 1, __ATOMIC_RELEASE);])],
 214      [libbacktrace_cv_sys_atomic=yes],
 215      [libbacktrace_cv_sys_atomic=no])
 216  fi])
 217 if test "$libbacktrace_cv_sys_atomic" = "yes"; then
 218   AC_DEFINE([HAVE_ATOMIC_FUNCTIONS], 1,
 219             [Define to 1 if you have the __atomic functions])
 220 fi
 221
 222 # The library needs to be able to read the executable itself.  Compile
 223 # a file to determine the executable format.  The awk script
 224 # filetype.awk prints out the file type.
 225 AC_CACHE_CHECK([output filetype],
 226 [libbacktrace_cv_sys_filetype],
 227 [filetype=
 228 AC_COMPILE_IFELSE(
 229   [AC_LANG_PROGRAM([int i;], [int j;])],
 230   [filetype=`${AWK} -f $srcdir/filetype.awk conftest.$ac_objext`],
 231   [AC_MSG_FAILURE([compiler failed])])
 232 libbacktrace_cv_sys_filetype=$filetype])
 233
 234 # Match the file type to decide what files to compile.
 235 FORMAT_FILE=
 236 backtrace_supports_data=yes
 237 case "$libbacktrace_cv_sys_filetype" in
 238 elf*) FORMAT_FILE="elf.lo" ;;
 239 pecoff) FORMAT_FILE="pecoff.lo"
 240         backtrace_supports_data=no
 241         ;;
 242 xcoff*) FORMAT_FILE="xcoff.lo"
 243         backtrace_supports_data=no
 244         ;;
 245 *) AC_MSG_WARN([could not determine output file type])
 246    FORMAT_FILE="unknown.lo"
 247    backtrace_supported=no
 248    ;;
 249 esac
 250 AC_SUBST(FORMAT_FILE)
 251
 252 # ELF defines.
 253 elfsize=
 254 case "$libbacktrace_cv_sys_filetype" in
 255 elf32) elfsize=32 ;;
 256 elf64) elfsize=64 ;;
 257 *)     elfsize=unused
 258 esac
 259 AC_DEFINE_UNQUOTED([BACKTRACE_ELF_SIZE], [$elfsize], [ELF size: 32 or 64])
 260
 261 # XCOFF defines.
 262 xcoffsize=
 263 case "$libbacktrace_cv_sys_filetype" in
 264 xcoff32) xcoffsize=32 ;;
 265 xcoff64) xcoffsize=64 ;;
 266 *)       xcoffsize=unused
 267 esac
 268 AC_DEFINE_UNQUOTED([BACKTRACE_XCOFF_SIZE], [$xcoffsize], [XCOFF size: 32 or 64])
 269
 270 BACKTRACE_SUPPORTED=0
 271 if test "$backtrace_supported" = "yes"; then
 272   BACKTRACE_SUPPORTED=1
 273 fi
 274 AC_SUBST(BACKTRACE_SUPPORTED)
 275
 276 BACKTRACE_SUPPORTS_DATA=0
 277 if test "$backtrace_supports_data" = "yes"; then
 278   BACKTRACE_SUPPORTS_DATA=1
 279 fi
 280 AC_SUBST(BACKTRACE_SUPPORTS_DATA)
 281
 282 GCC_HEADER_STDINT(gstdint.h)
 283
 284 AC_CHECK_HEADERS(sys/mman.h)
 285 if test "$ac_cv_header_sys_mman_h" = "no"; then
 286   have_mmap=no
 287 else
 288   if test -n "${with_target_subdir}"; then
 289     # When built as a GCC target library, we can't do a link test.  We
 290     # simply assume that if we have mman.h, we have mmap.
 291     have_mmap=yes
 292     case "${host}" in
 293     spu-*-*|*-*-msdosdjgpp)
 294         # The SPU does not have mmap, but it has a sys/mman.h header file
 295         # containing "mmap_eaddr" and the mmap flags, confusing the test.
 296         # DJGPP also has sys/man.h, but no mmap
 297         have_mmap=no ;;
 298     esac
 299   else
 300     AC_CHECK_FUNC(mmap, [have_mmap=yes], [have_mmap=no])
 301   fi
 302 fi
 303 if test "$have_mmap" = "no"; then
 304   VIEW_FILE=read.lo
 305   ALLOC_FILE=alloc.lo
 306 else
 307   VIEW_FILE=mmapio.lo
 308   AC_PREPROC_IFELSE([
 309 #include <sys/mman.h>
 310 #if !defined(MAP_ANONYMOUS) && !defined(MAP_ANON)
 311   #error no MAP_ANONYMOUS
 312 #endif
 313 ], [ALLOC_FILE=mmap.lo], [ALLOC_FILE=alloc.lo])
 314 fi
 315 AC_SUBST(VIEW_FILE)
 316 AC_SUBST(ALLOC_FILE)
 317
 318 BACKTRACE_USES_MALLOC=0
 319 if test "$ALLOC_FILE" = "alloc.lo"; then
 320   BACKTRACE_USES_MALLOC=1
 321 fi
 322 AC_SUBST(BACKTRACE_USES_MALLOC)
 323
 324 # Check for dl_iterate_phdr.
 325 AC_CHECK_HEADERS(link.h)
 326 if test "$ac_cv_header_link_h" = "no"; then
 327   have_dl_iterate_phdr=no
 328 else
 329   if test -n "${with_target_subdir}"; then
 330     # When built as a GCC target library, we can't do a link test.
 331     AC_EGREP_HEADER([dl_iterate_phdr], [link.h], [have_dl_iterate_phdr=yes],
 332                     [have_dl_iterate_phdr=no])
 333     case "${host}" in
 334     *-*-solaris2.10*)
 335         # Avoid dl_iterate_phdr on Solaris 10, where it is in the
 336         # header file but is only in -ldl.
 337         have_dl_iterate_phdr=no ;;
 338     esac
 339   else
 340     AC_CHECK_FUNC([dl_iterate_phdr], [have_dl_iterate_phdr=yes],
 341                   [have_dl_iterate_phdr=no])
 342   fi
 343 fi
 344 if test "$have_dl_iterate_phdr" = "yes"; then
 345   AC_DEFINE(HAVE_DL_ITERATE_PHDR, 1, [Define if dl_iterate_phdr is available.])
 346 fi
 347
 348 # Check for loadquery.
 349 AC_CHECK_HEADERS(sys/ldr.h)
 350 if test "$ac_cv_header_sys_ldr_h" = "no"; then
 351   have_loadquery=no
 352 else
 353   if test -n "${with_target_subdir}"; then
 354     # When built as a GCC target library, we can't do a link test.
 355     AC_EGREP_HEADER([loadquery], [sys/ldr.h], [have_loadquery=yes],
 356                     [have_loadquery=no])
 357   else
 358     AC_CHECK_FUNC([loadquery], [have_loadquery=yes],
 359                   [have_loadquery=no])
 360   fi
 361 fi
 362 if test "$have_loadquery" = "yes"; then
 363   AC_DEFINE(HAVE_LOADQUERY, 1, [Define if AIX loadquery is available.])
 364 fi
 365
 366 # Check for the fcntl function.
 367 if test -n "${with_target_subdir}"; then
 368    case "${host}" in
 369    *-*-mingw*) have_fcntl=no ;;
 370    spu-*-*) have_fcntl=no ;;
 371    *) have_fcntl=yes ;;
 372    esac
 373 else
 374   AC_CHECK_FUNC(fcntl, [have_fcntl=yes], [have_fcntl=no])
 375 fi
 376 if test "$have_fcntl" = "yes"; then
 377   AC_DEFINE([HAVE_FCNTL], 1,
 378             [Define to 1 if you have the fcntl function])
 379 fi
 380
 381 AC_CHECK_DECLS(strnlen)
 382 AC_CHECK_FUNCS(lstat readlink)
 383
 384 # Check for getexecname function.
 385 if test -n "${with_target_subdir}"; then
 386    case "${host}" in
 387    *-*-solaris2*) have_getexecname=yes ;;
 388    *) have_getexecname=no ;;
 389    esac
 390 else
 391   AC_CHECK_FUNC(getexecname, [have_getexecname=yes], [have_getexecname=no])
 392 fi
 393 if test "$have_getexecname" = "yes"; then
 394   AC_DEFINE(HAVE_GETEXECNAME, 1, [Define if getexecname is available.])
 395 fi
 396
 397 # Check for the clock_gettime function.
 398 AC_CHECK_FUNCS(clock_gettime)
 399 clock_gettime_link=
 400 # At least for glibc, clock_gettime is in librt.  But don't
 401 # pull that in if it still doesn't give us the function we want.  This
 402 # test is copied from libgomp, and modified to not link in -lrt as
 403 # we're using this for test timing only.
 404 if test "$ac_cv_func_clock_gettime" = no; then
 405   AC_CHECK_LIB(rt, clock_gettime,
 406     [CLOCK_GETTIME_LINK=-lrt
 407      AC_DEFINE(HAVE_CLOCK_GETTIME, 1,
 408                [Define to 1 if you have the `clock_gettime' function.])])
 409 fi
 410 AC_SUBST(CLOCK_GETTIME_LINK)
 411
 412 dnl Test whether the compiler supports the -pthread option.
 413 AC_CACHE_CHECK([whether -pthread is supported],
 414 [libgo_cv_lib_pthread],
 415 [CFLAGS_hold=$CFLAGS
 416 CFLAGS="$CFLAGS -pthread"
 417 AC_COMPILE_IFELSE([[int i;]],
 418 [libgo_cv_lib_pthread=yes],
 419 [libgo_cv_lib_pthread=no])
 420 CFLAGS=$CFLAGS_hold])
 421 PTHREAD_CFLAGS=
 422 if test "$libgo_cv_lib_pthread" = yes; then
 423   PTHREAD_CFLAGS=-pthread
 424 fi
 425 AC_SUBST(PTHREAD_CFLAGS)
 426
 427 AM_CONDITIONAL(HAVE_PTHREAD, test "$libgo_cv_lib_pthread" = yes)
 428
 429 AC_CHECK_LIB([z], [compress], [])
 430 if test $ac_cv_lib_z_compress = "yes"; then
 431   AC_DEFINE(HAVE_ZLIB, 1, [Define if -lz is available.])
 432 fi
 433 AM_CONDITIONAL(HAVE_ZLIB, test "$ac_cv_lib_z_compress" = yes)
 434
 435 dnl Test whether the linker supports the --compress_debug_sections option.
 436 AC_CACHE_CHECK([whether --compress-debug-sections is supported],
 437 [libgo_cv_ld_compress],
 438 [LDFLAGS_hold=$LDFLAGS
 439 LDFLAGS="$LDFLAGS -Wl,--compress-debug-sections=zlib-gnu"
 440 AC_LINK_IFELSE([AC_LANG_PROGRAM(,)],
 441 [libgo_cv_ld_compress=yes],
 442 [libgo_cv_ld_compress=no])
 443 LDFLAGS=$LDFLAGS_hold])
 444 AM_CONDITIONAL(HAVE_COMPRESSED_DEBUG, test "$libgo_cv_ld_compress" = yes)
 445
 446 AC_ARG_VAR(OBJCOPY, [location of objcopy])
 447 AC_CHECK_PROG(OBJCOPY, objcopy, objcopy,)
 448 AC_CACHE_CHECK([whether objcopy supports debuglink],
 449 [libbacktrace_cv_objcopy_debuglink],
 450 [if test -n "${with_target_subdir}"; then
 451   libbacktrace_cv_objcopy_debuglink=no
 452 elif ${OBJCOPY} --add-gnu-debuglink=x /bin/ls /tmp/ls$$; then
 453   rm -f /tmp/ls$$
 454   libbacktrace_cv_objcopy_debuglink=yes
 455 else
 456   libbacktrace_cv_objcopy_debuglink=no
 457 fi])
 458 AM_CONDITIONAL(HAVE_OBJCOPY_DEBUGLINK, test "$libbacktrace_cv_objcopy_debuglink" = yes)
 459
 460 AC_CACHE_CHECK([whether tests can run],
 461   [libbacktrace_cv_sys_native],
 462   [AC_RUN_IFELSE([AC_LANG_PROGRAM([], [return 0;])],
 463      [libbacktrace_cv_sys_native=yes],
 464      [libbacktrace_cv_sys_native=no],
 465      [libbacktrace_cv_sys_native=no])])
 466 AM_CONDITIONAL(NATIVE, test "$libbacktrace_cv_sys_native" = "yes")
 467
 468 if test "${multilib}" = "yes"; then
 469   multilib_arg="--enable-multilib"
 470 else
 471   multilib_arg=
 472 fi
 473
 474 AC_CONFIG_FILES(Makefile backtrace-supported.h)
 475
 476 # We need multilib support, but only if configuring for the target.
 477 AC_CONFIG_COMMANDS([default],
 478 [if test -n "$CONFIG_FILES"; then
 479    if test -n "${with_target_subdir}"; then
 480      # Multilibs need MULTISUBDIR defined correctly in certain makefiles so
 481      # that multilib installs will end up installed in the correct place.
 482      # The testsuite needs it for multilib-aware ABI baseline files.
 483      # To work around this not being passed down from config-ml.in ->
 484      # srcdir/Makefile.am -> srcdir/{src,libsupc++,...}/Makefile.am, manually
 485      # append it here.  Only modify Makefiles that have just been created.
 486      #
 487      # Also, get rid of this simulated-VPATH thing that automake does.
 488      cat > vpsed << \_EOF
 489   s!`test -f '$<' || echo '$(srcdir)/'`!!
 490 _EOF
 491      for i in $SUBDIRS; do
 492       case $CONFIG_FILES in
 493        *${i}/Makefile*)
 494          #echo "Adding MULTISUBDIR to $i/Makefile"
 495          sed -f vpsed $i/Makefile > tmp
 496          grep '^MULTISUBDIR =' Makefile >> tmp
 497          mv tmp $i/Makefile
 498          ;;
 499       esac
 500      done
 501      rm vpsed
 502    fi
 503  fi
 504 ],
 505 [
 506 # Variables needed in config.status (file generation) which aren't already
 507 # passed by autoconf.
 508 SUBDIRS="$SUBDIRS"
 509 ])
 510
 511 AC_OUTPUT