guile/configure.ac

dnl   configuration script for Guile
dnl   Process this file with autoconf to produce configure.
dnl

define(GUILE_CONFIGURE_COPYRIGHT,[[
Copyright 1998-2022 Free Software Foundation, Inc.

This file is part of Guile.

Guile is free software: you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published
by the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

Guile is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
License for more details.

You should have received a copy of the GNU Lesser General Public
License along with Guile.  If not, see
<https://www.gnu.org/licenses/>.
]])

AC_PREREQ(2.64)

AC_INIT([GNU Guile],
        m4_esyscmd([build-aux/git-version-gen --match v3.0.\* .tarball-version]),
        [bug-guile@gnu.org])
AC_CONFIG_AUX_DIR([build-aux])
AC_CONFIG_MACRO_DIR([m4])
AC_CONFIG_SRCDIR(GUILE-VERSION)

AC_CANONICAL_TARGET

dnl Use `serial-tests' so the output `check-guile' is not hidden
dnl (`parallel-tests' is the default in Automake 1.13.)
dnl `serial-tests' was introduced in Automake 1.12.
AM_INIT_AUTOMAKE([1.12 gnu no-define -Wall -Wno-override \
  serial-tests color-tests dist-lzip dist-xz])
m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])], [AC_SUBST([AM_DEFAULT_VERBOSITY],1)])

AC_COPYRIGHT(GUILE_CONFIGURE_COPYRIGHT)
AC_CONFIG_SRCDIR([GUILE-VERSION])

. $srcdir/GUILE-VERSION
GUILE_VERSION="$PACKAGE_VERSION"

AC_CONFIG_HEADERS([config.h])
AH_TOP(/*GUILE_CONFIGURE_COPYRIGHT*/)

dnl We require the pkg.m4 set of macros from pkg-config.
dnl Make sure it's available.
m4_pattern_forbid([PKG_CHECK_MODULES])

#--------------------------------------------------------------------

AC_LANG([C])

dnl Some more checks for Win32
AC_CANONICAL_HOST

AC_LIBTOOL_WIN32_DLL

AC_PROG_INSTALL
AC_PROG_CC

AC_MSG_CHECKING([whether the compiler supports -flto])
old_CFLAGS="$CFLAGS"
LTO_CFLAGS="-flto"
CFLAGS="$CFLAGS $LTO_CFLAGS"
AC_COMPILE_IFELSE([AC_LANG_SOURCE([int foo;])],, [LTO_CFLAGS=])
CFLAGS="$old_CFLAGS"
if test -n "$LTO_CFLAGS"; then
  AC_MSG_RESULT([yes])
else
  AC_MSG_RESULT([no])
fi

AC_ARG_ENABLE(lto,
  [AS_HELP_STRING([--enable-lto]
                  [enable link-time optimization for libguile])],
  [],
  [if test -z "$LTO_CFLAGS"; then enable_lto=no; else enable_lto=yes; fi])
case "$enable_lto" in
  yes | y)
    if test -z "$LTO_CFLAGS"; then
      AC_MSG_ERROR([--enable-lto=$enable_lto unsupported for $CC])
    fi
    CFLAGS="$CFLAGS $LTO_CFLAGS"
    AC_MSG_CHECKING([for lto-specific prefix for ar, nm, objcopy, ranlib])
    if test "$GCC" = yes; then
       TOOLCHAIN_PREFIX=gcc
    else
       # Assuming LLVM if not GCC.  Probably won't hurt.
       TOOLCHAIN_PREFIX=llvm
    fi
    AC_MSG_RESULT([$TOOLCHAIN_PREFIX])
    AC_CHECK_TOOLS([AR], [$TOOLCHAIN_PREFIX-ar ar])
    AC_CHECK_TOOLS([NM], [$TOOLCHAIN_PREFIX-nm nm])
    AC_CHECK_TOOLS([OBJCOPY], [$TOOLCHAIN_PREFIX-objcopy objcopy])
    AC_CHECK_TOOLS([RANLIB], [$TOOLCHAIN_PREFIX-ranlib ranlib])
    ;;
  no | n)
    ;;
  *)
    AC_MSG_ERROR([unexpected --enable-lto=$enable_lto])
    ;;
esac

# Sadly, there is no released version of Autoconf with a nice
# C11-ensuring macro.  This should work for gcc/clang within the last 5
# years though.
AC_MSG_CHECKING([how to enable C11 support])
if test "$GCC" = yes; then
  AC_MSG_RESULT([-std=gnu11])
  CC="$CC -std=gnu11"
else
  dnl Guile requires C99 or later.
  AC_PROG_CC_C99
  if test "$ac_cv_prog_cc_c99" = "xno"; then
    AC_MSG_ERROR([Support for C99 required but not found.])
  fi
fi

gl_EARLY
AC_PROG_CPP
AC_PROG_SED
AC_PROG_AWK
AC_PROG_LN_S
AM_PROG_AR

dnl Gnulib.
gl_INIT

dnl We provide our own lib/glthread/lock.h, so let other Gnulib modules
dnl know that we have it.  This allows them to be compiled with adequate
dnl locking support.  See <http://bugs.gnu.org/14404>.
AC_DEFINE([GNULIB_LOCK], [1],
  [Define to allow Gnulib modules to use Guile's locks.])


# for per-target cflags in the libguile subdir
AM_PROG_CC_C_O

AC_LIBTOOL_DLOPEN
AC_PROG_LIBTOOL

AM_CONDITIONAL([HAVE_SHARED_LIBRARIES], [test "x$enable_shared" = "xyes"])

# Some systems provide dlopen via libc; others require -ldl.
AC_SEARCH_LIBS([dlopen], [dl])

AC_CHECK_PROG(have_makeinfo, makeinfo, yes, no)
AM_CONDITIONAL(HAVE_MAKEINFO, test "$have_makeinfo" = yes)

AM_PATH_LISPDIR

AC_DEFINE_UNQUOTED([HOST_TYPE], ["$host"],
  [Define to the host's GNU triplet.])

#--------------------------------------------------------------------
#
# User options (after above tests that may set default CFLAGS etc.)
#
#--------------------------------------------------------------------

GUILE_ERROR_ON_WARNING="no"

AC_ARG_ENABLE(error-on-warning,
  [  --enable-error-on-warning    treat compile warnings as errors],
  [case "${enableval}" in
     yes | y) GUILE_ERROR_ON_WARNING="yes" ;;
     no | n)  GUILE_ERROR_ON_WARNING="no" ;;
     *) AC_MSG_ERROR(bad value ${enableval} for --enable-error-on-warning) ;;
   esac])

AC_ARG_ENABLE(debug-malloc,
  [  --enable-debug-malloc   include malloc debugging code],
  if test "$enable_debug_malloc" = y || test "$enable_debug_malloc" = yes; then
    AC_DEFINE([GUILE_DEBUG_MALLOC], 1,
      [Define this if you want to debug scm_must_malloc/realloc/free calls.])
  fi)

# Check if JIT is available.
GUILE_ENABLE_JIT

SCM_I_GSC_GUILE_DEBUG=0
AC_ARG_ENABLE(guile-debug,
  [AS_HELP_STRING([--enable-guile-debug],
                  [include internal debugging functions])],
  if test "$enable_guile_debug" = y || test "$enable_guile_debug" = yes; then
    SCM_I_GSC_GUILE_DEBUG=1
  fi)

AC_ARG_ENABLE(posix,
  [  --disable-posix         omit non-essential POSIX interfaces],,
  enable_posix=yes)

AC_ARG_ENABLE(networking,
  [  --disable-networking    omit networking interfaces],,
  enable_networking=yes)

AC_ARG_ENABLE(regex,
  [  --disable-regex         omit regular expression interfaces],,
  enable_regex=yes)

AC_ARG_ENABLE(tmpnam,
  AS_HELP_STRING([--disable-tmpnam],[omit POSIX tmpnam]),,
  enable_tmpnam=yes)

AC_ARG_ENABLE([deprecated],
  AS_HELP_STRING([--disable-deprecated],[omit deprecated features]))

if test "$enable_deprecated" = no; then
  SCM_I_GSC_ENABLE_DEPRECATED=0
  warn_default=no
else
  if test "$enable_deprecated" = yes || test "$enable_deprecated" = ""; then
    warn_default=summary
  elif test "$enable_deprecated" = shutup; then
    warn_default=no
  else
    warn_default=$enable_deprecated
  fi
  SCM_I_GSC_ENABLE_DEPRECATED=1
fi
AC_DEFINE_UNQUOTED([SCM_WARN_DEPRECATED_DEFAULT], "$warn_default",
[Define this to control the default warning level for deprecated features.])

dnl  Added the following configure option in January 2008 following
dnl  investigation of problems with "64" system and library calls on
dnl  Darwin (MacOS X).  The libguile code (_scm.h) assumes that if a
dnl  system has stat64, it will have all the other 64 APIs too; but on
dnl  Darwin, stat64 is there but other APIs are missing.
dnl 
dnl  It also appears, from the Darwin docs, that most system call APIs
dnl  there (i.e. the traditional ones _without_ "64" in their names) have
dnl  been 64-bit-capable for a long time now, so it isn't necessary to
dnl  use "64" versions anyway.  For example, Darwin's off_t is 64-bit.
dnl 
dnl  A similar problem has been reported for HP-UX:
dnl  http://www.nabble.com/Building-guile-1.8.2-on-hpux-td13106681.html
dnl 
dnl  Therefore, and also because a Guile without LARGEFILE64 support is
dnl  better than no Guile at all, we provide this option to suppress
dnl  trying to use "64" calls.
dnl 
dnl  It may be that for some 64-bit function on Darwin/HP-UX we do need
dnl  to use a "64" call, and hence that by using --without-64-calls we're
dnl  missing out on that.  If so, someone can work on that in the future.
dnl  For now, --without-64-calls allows Guile to build on OSs where it
dnl  wasn't building before.
AC_MSG_CHECKING([whether to use system and library "64" calls])
AC_ARG_WITH([64-calls],
  AS_HELP_STRING([--without-64-calls],
                 [don't attempt to use system and library calls with "64" in their names]),
  [use_64_calls=$withval],
  [use_64_calls=yes
   case $host in
     *-apple-darwin* )
       use_64_calls=no
       ;;
     powerpc-ibm-aix* )
       use_64_calls=no
       ;;
   esac])
AC_MSG_RESULT($use_64_calls)
case "$use_64_calls" in
  y* )
    AC_DEFINE([GUILE_USE_64_CALLS], 1,
      [Define to 1 in order to try to use "64" versions of system and library calls.])
    ;;
esac

#--------------------------------------------------------------------

dnl Check for dynamic linking

use_modules=yes
AC_ARG_WITH(modules,
[  --with-modules[=FILES]  Add support for dynamic modules],
use_modules="$withval")
test -z "$use_modules" && use_modules=yes
DLPREOPEN=
if test "$use_modules" != no; then
  if test "$use_modules" = yes; then
    DLPREOPEN="-dlpreopen force"
  else
    DLPREOPEN="-export-dynamic"
    for module in $use_modules; do
      DLPREOPEN="$DLPREOPEN -dlopen $module"
    done
  fi
fi

dnl files which are destined for separate modules.

if test "$use_modules" != no; then
   AC_LIBOBJ([dynl])
   AC_DEFINE([HAVE_MODULES], 1,
     [Define this if you want support for dynamically loaded modules in Guile.])
fi

if test "$enable_posix" = yes; then
   AC_LIBOBJ([posix])
   AC_DEFINE([HAVE_POSIX], 1,
     [Define this if you want support for non-essential POSIX system calls in Guile.])
fi

if test "$enable_networking" = yes; then
   AC_LIBOBJ([net_db])
   AC_LIBOBJ([socket])
   AC_DEFINE([HAVE_NETWORKING], 1,
     [Define this if you want support for networking in Guile.])
fi

if test "$enable_debug_malloc" = yes; then
   AC_LIBOBJ([debug-malloc])
fi

AC_CHECK_LIB(uca, __uc_get_ar_bsp)

AC_C_CONST

# "volatile" is used in a couple of tests below.
AC_C_VOLATILE

AC_C_INLINE
if test "$ac_cv_c_inline" != no; then
  SCM_I_GSC_C_INLINE="\"${ac_cv_c_inline}\""
else
  SCM_I_GSC_C_INLINE=NULL
fi
AC_CHECK_LIB(uca, __uc_get_ar_bsp)

AC_C_BIGENDIAN

AC_C_LABELS_AS_VALUES

AC_CHECK_SIZEOF(char)
AC_CHECK_SIZEOF(unsigned char)
AC_CHECK_SIZEOF(short)
AC_CHECK_SIZEOF(unsigned short)
AC_CHECK_SIZEOF(int)
AC_CHECK_SIZEOF(unsigned int)
AC_CHECK_SIZEOF(long)
AC_CHECK_SIZEOF(unsigned long)
AC_CHECK_SIZEOF(size_t)
AC_CHECK_SIZEOF(long long)
AC_CHECK_SIZEOF(unsigned long long)
AC_CHECK_SIZEOF(__int64)
AC_CHECK_SIZEOF(unsigned __int64)
AC_CHECK_SIZEOF(void *)
AC_CHECK_SIZEOF(intptr_t)
AC_CHECK_SIZEOF(uintptr_t)
AC_CHECK_SIZEOF(ptrdiff_t)
AC_CHECK_SIZEOF(size_t)
AC_CHECK_SIZEOF(off_t)

if test "$ac_cv_sizeof_long" -gt "$ac_cv_sizeof_void_p"; then
  AC_MSG_ERROR(long does not fit into a void*)
fi

if test "$ac_cv_sizeof_ptrdiff_t" -ne 0; then
  SCM_I_GSC_T_PTRDIFF='"ptrdiff_t"'
else
  SCM_I_GSC_T_PTRDIFF='"long"'
fi
AC_SUBST([SCM_I_GSC_T_PTRDIFF])

AC_CHECK_HEADERS([stdatomic.h])

AC_MSG_CHECKING([for which prebuilt binary set to use during bootstrap])
SCM_PREBUILT_BINARIES=
case "$ac_cv_c_bigendian-$ac_cv_sizeof_void_p" in
  yes-8) SCM_PREBUILT_BINARIES=64-bit-big-endian;;
  yes-4) SCM_PREBUILT_BINARIES=32-bit-big-endian;;
  no-8) SCM_PREBUILT_BINARIES=64-bit-little-endian;;
  no-4) SCM_PREBUILT_BINARIES=32-bit-little-endian;;
  *) AC_MSG_ERROR([Unexpected endianness+pointer size combination.])
esac
AC_MSG_RESULT($SCM_PREBUILT_BINARIES)
AC_SUBST([SCM_PREBUILT_BINARIES])

AC_HEADER_STDC
AC_HEADER_TIME
AC_HEADER_SYS_WAIT
AC_HEADER_DIRENT

# Reason for checking:
#
#   HP-UX 11.11 (at least) doesn't provide `struct dirent64', even
#   with `_LARGEFILE64_SOURCE', so check whether it's available.
#
AC_CHECK_MEMBER([struct dirent64.d_name],
  [SCM_I_GSC_HAVE_STRUCT_DIRENT64=1], [SCM_I_GSC_HAVE_STRUCT_DIRENT64=0],
  [ #ifndef _LARGEFILE64_SOURCE
    # define _LARGEFILE64_SOURCE
    #endif

    /* Per Autoconf manual.  */
    #include <sys/types.h>
    #ifdef HAVE_DIRENT_H
    # include <dirent.h>
    #else
    # define dirent direct
    # ifdef HAVE_SYS_NDIR_H
    #  include <sys/ndir.h>
    # endif
    # ifdef HAVE_SYS_DIR_H
    #  include <sys/dir.h>
    # endif
    # ifdef HAVE_NDIR_H
    #  include <ndir.h>
    # endif
    #endif ])
AC_SUBST([SCM_I_GSC_HAVE_STRUCT_DIRENT64])

# Reasons for testing:
#   complex.h - new in C99
#   fenv.h - available in C99, but not older systems
#   machine/fpu.h - on Tru64 5.1b, the declaration of fesetround(3) is in
#     this file instead of <fenv.h>
#   process.h - mingw specific
#   sched.h - missing on MinGW
#   sys/sendfile.h - non-POSIX, found in glibc
#
AC_CHECK_HEADERS([complex.h fenv.h io.h libc.h limits.h memory.h process.h string.h \
sys/dir.h sys/ioctl.h sys/select.h \
sys/time.h sys/timeb.h sys/times.h sys/stdtypes.h sys/types.h \
sys/utime.h time.h unistd.h utime.h pwd.h grp.h sys/utsname.h \
direct.h machine/fpu.h sched.h sys/sendfile.h])

# "complex double" is new in C99, and "complex" is only a keyword if
# <complex.h> is included
AC_CHECK_TYPES(complex double,,,
[#if HAVE_COMPLEX_H
#include <complex.h>
#endif])

# On MacOS X <sys/socklen.h> contains socklen_t, so must include that
# when testing.
AC_CHECK_TYPE(socklen_t, ,
  [AC_DEFINE_UNQUOTED([socklen_t], int,
                      [Define to `int' if <sys/socket.h> does not define.])],
  [#if HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include <sys/socket.h>
])

AC_CHECK_TYPES([struct ip_mreq], , , [#include <netinet/in.h>])

GUILE_HEADER_LIBC_WITH_UNISTD

AC_TYPE_GETGROUPS
AC_TYPE_SIGNAL
AC_TYPE_MODE_T

dnl Check whether we need -lm.
LT_LIB_M
LIBS="$LIBS $LIBM"

AC_CHECK_FUNCS(gethostbyname)
if test $ac_cv_func_gethostbyname = no; then
    AC_CHECK_LIB(nsl, gethostbyname)
fi

AC_CHECK_FUNCS(connect)
if test $ac_cv_func_connect = no; then
    AC_CHECK_LIB(socket, connect)
fi

dnl
dnl Check for Winsock and other functionality on Win32 (*not* CygWin)
dnl
EXTRA_DEFS=""
mingw_libpath=false
case $host in
  *-*-mingw*)
    AC_CHECK_HEADER(winsock2.h, [AC_DEFINE([HAVE_WINSOCK2_H], 1,
      [Define if you have the <winsock2.h> header file.])])
    AC_CHECK_LIB(ws2_32, main)
    AC_LIBOBJ([posix-w32])
    if test "$enable_shared" = yes ; then
      EXTRA_DEFS="-DSCM_IMPORT"
      AC_DEFINE([USE_DLL_IMPORT], 1,
        [Define if you need additional CPP macros on Win32 platforms.])
    fi
    mingw_libpath=true
    ;;
esac
AC_SUBST(EXTRA_DEFS)
AM_CONDITIONAL([MINGW_LIBPATH], [test x$mingw_libpath = xtrue])

# Reasons for testing:
#   crt_externs.h - Darwin specific
#
AC_CHECK_HEADERS([assert.h crt_externs.h])

# Reasons for testing:
#   DINFINITY - OSF specific
#   DQNAN - OSF specific
#       (DINFINITY and DQNAN are actually global variables, not functions)
#   chsize - an MS-DOS-ism, found in mingw
#   cexp, clog - not in various pre-c99 systems, and note that it's possible
#       for gcc to provide the "complex double" type but the system to not
#       have functions like cexp and clog
#   clog10 - not in mingw (though others like clog and csqrt are)
#   fesetround - available in C99, but not older systems
#   ftruncate - posix, but probably not older systems (current mingw
#               has it as an inline for chsize)
#   ioctl - not in mingw.
#   gmtime_r - recent posix, not on old systems
#   readdir_r - recent posix, not on old systems
#   readdir64_r - not available on HP-UX 11.11
#   stat64 - SuS largefile stuff, not on old systems
#   sysconf - not on old systems
#   truncate - not in mingw
#   isblank - available as a GNU extension or in C99
#   _NSGetEnviron - Darwin specific
#   strcoll_l, newlocale, uselocale, utimensat - POSIX.1-2008
#   strtol_l - non-POSIX, found in glibc
#   fork - unavailable on Windows
#   sched_getaffinity, sched_setaffinity - GNU extensions (glibc)
#   sendfile - non-POSIX, found in glibc
#
AC_CHECK_FUNCS([DINFINITY DQNAN cexp chsize clog clog10 ctermid         \
  fesetround ftime ftruncate fchown fchmod getcwd geteuid getsid        \
  gettimeofday getuid getgid gmtime_r ioctl lstat mkdir mkdtemp mknod   \
  nice readlink rename rmdir setegid seteuid                            \
  setlocale setuid setgid setpgid setsid sigaction siginterrupt stat64  \
  strptime symlink sync sysconf tcgetpgrp tcsetpgrp uname waitpid       \
  strdup system usleep atexit on_exit chown link fcntl ttyname getpwent \
  getgrent kill getppid getpgrp fork setitimer getitimer strchr strcmp  \
  index bcopy memcpy rindex truncate isblank _NSGetEnviron              \
  strcoll strcoll_l strtod_l strtol_l newlocale uselocale utimensat     \
  sched_getaffinity sched_setaffinity sendfile])

# The newlib C library uses _NL_ prefixed locale langinfo constants.
AC_CHECK_DECLS([_NL_NUMERIC_GROUPING], [], [], [[#include <langinfo.h>]])

# Reasons for testing:
#   netdb.h - not in mingw
#   sys/param.h - not in mingw
#   pthread.h - only available with pthreads.  ACX_PTHREAD doesn't
#       check this specifically, we need it for the timespec test below.
#   pthread_np.h - available on FreeBSD
#   sethostname - the function itself check because it's not in mingw,
#       the DECL is checked because Solaris 10 doens't have in any header
#   hstrerror - on Tru64 5.1b the symbol is available in libc but the
#       declaration isn't anywhere.
#   cuserid - on Tru64 5.1b the declaration is documented to be available
#       only with `_XOPEN_SOURCE' or some such.
#
AC_CHECK_HEADERS([crypt.h netdb.h pthread.h pthread_np.h sys/param.h sys/resource.h sys/file.h sys/mman.h])
AC_CHECK_FUNCS(chroot flock getlogin cuserid getpriority setpriority getpass sethostname gethostname)
AC_CHECK_DECLS([sethostname, hstrerror, cuserid])

# crypt() may or may not be available, for instance in some countries there
# are restrictions on cryptography.
#
# crypt() might be in libc (eg. OpenBSD), or it might be in a separate
# -lcrypt library (eg. Debian GNU/Linux).
#
# On HP-UX 11, crypt() is in libc and there's a dummy libcrypt.a.  We must
# be careful to avoid -lcrypt in this case, since libtool will see there's
# only a static libcrypt and decide to build only a static libguile.
#
# AC_SEARCH_LIBS lets us add -lcrypt to LIBS only if crypt() is not in the
# libraries already in that list.
#
AC_SEARCH_LIBS(crypt, crypt,
  [AC_DEFINE([HAVE_CRYPT],1,
             [Define to 1 if you have the `crypt' function.])])

# When compiling with GCC on some OSs (Solaris, AIX), _Complex_I doesn't
# work; in the reported cases so far, 1.0fi works well instead.  According
# to the C99 spec, the complex.h header must provide a working definition
# of _Complex_I, so we always try _Complex_I first.  The 1.0fi fallback
# is a workaround for the failure of some systems to conform to C99.
if test "$ac_cv_type_complex_double" = yes; then
  AC_MSG_CHECKING([for i])
  AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#if HAVE_COMPLEX_H
#include <complex.h>
#endif
complex double z;
]], [[
z = _Complex_I;
]])],
    [AC_DEFINE([GUILE_I],_Complex_I,[The imaginary unit (positive square root of -1).])
     AC_MSG_RESULT([_Complex_I])],
    [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#if HAVE_COMPLEX_H
#include <complex.h>
#endif
complex double z;
]],[[
z = 1.0fi;
]])],
  [AC_DEFINE([GUILE_I],1.0fi)
   AC_MSG_RESULT([1.0fi])],
  [ac_cv_type_complex_double=no
   AC_MSG_RESULT([not available])])])
fi

# glibc 2.3.6 (circa 2006) and various prior versions had a bug where
# csqrt(-i) returned a negative real part, when it should be positive
# for the principal root.
#
if test "$ac_cv_type_complex_double" = yes; then

  AC_CACHE_CHECK([whether csqrt is usable],
    guile_cv_use_csqrt,
    [AC_RUN_IFELSE([AC_LANG_SOURCE([[
#include <complex.h>
/* "volatile" is meant to prevent gcc from calculating the sqrt as a
   constant, we want to test libc. */
volatile complex double z = - _Complex_I;
int
main (void)
{
  z = csqrt (z);	
  if (creal (z) > 0.0)
    return 0;  /* good */
  else
    return 1;  /* bad */
}]])],
    [guile_cv_use_csqrt=yes],
    [guile_cv_use_csqrt="no, glibc 2.3 bug"],
    [guile_cv_use_csqrt="yes, hopefully (cross-compiling)"])])
  case $guile_cv_use_csqrt in
    yes*)
      AC_DEFINE([HAVE_USABLE_CSQRT], 1, [Define to 1 if csqrt is bug-free])
      ;;
  esac
fi

# Cygwin and Hurd (circa 2017) and various prior versions defined stub
# versions of the virtual and profiling itimers that would always fail
# when called.
if test "$ac_cv_func_getitimer" = yes; then

  AC_CACHE_CHECK([whether getitimer(ITIMER_PROF) is usable],
    guile_cv_use_getitimer_prof,
    [AC_RUN_IFELSE([AC_LANG_SOURCE([[
#include <sys/time.h>
int
main (void)
{
  struct itimerval I;
  if (getitimer (ITIMER_PROF, &I) == 0)
    return 0;  /* good */
  else
    return 1;  /* bad */
}]])],
    [guile_cv_use_getitimer_prof=yes],
    [guile_cv_use_getitimer_prof=no],
    [guile_cv_use_getitimer_prof="yes, hopefully (cross-compiling)"])])
  case $guile_cv_use_getitimer_prof in
    yes*)
      AC_DEFINE([HAVE_USABLE_GETITIMER_PROF], 1, [Define to 1 if getitimer(ITIMER_PROF, ...) is functional])
      ;;
  esac

  AC_CACHE_CHECK([whether getitimer(ITIMER_VIRTUAL) is usable],
    guile_cv_use_getitimer_virtual,
    [AC_RUN_IFELSE([AC_LANG_SOURCE([[
#include <sys/time.h>
int
main (void)
{
  struct itimerval I;
  if (getitimer (ITIMER_VIRTUAL, &I) == 0)
    return 0;  /* good */
  else
    return 1;  /* bad */
}]])],
    [guile_cv_use_getitimer_virtual=yes],
    [guile_cv_use_getitimer_virtual=no],
    [guile_cv_use_getitimer_virtual="yes, hopefully (cross-compiling)"])])
  case $guile_cv_use_getitimer_virtual in
    yes*)
      AC_DEFINE([HAVE_USABLE_GETITIMER_VIRTUAL], 1, [Define to 1 if getitimer(ITIMER_VIRTUAL, ...) is functional])
      ;;
  esac
fi


AC_CACHE_SAVE

dnl GMP tests

SCM_I_GSC_ENABLE_MINI_GMP=0
AC_ARG_ENABLE(mini-gmp,
  [AS_HELP_STRING([--enable-mini-gmp],
                  [use mini-gmp instead of the full GMP library])])

if test "x$enable_mini_gmp" = xyes || test "x$enable_mini_gmp" = xy; then
  SCM_I_GSC_ENABLE_MINI_GMP=1
else
  AC_LIB_HAVE_LINKFLAGS([gmp],[],[#include <gmp.h>], [mpz_import (0,0,0,0,0,0,0);])
  if test "x$HAVE_LIBGMP" != "xyes"; then
    AC_MSG_ERROR([GNU MP 4.1 or greater not found; either install it, or pass '--enable-mini-gmp' to use included less-optimal arbitrary-precision integer support.])
  fi
  if test "x$LIBGMP_PREFIX" != "x"; then
    CPPFLAGS="-I$LIBGMP_PREFIX $CPPFLAGS"
  fi
  AC_CHECK_DECLS([mpz_inits], [], [], [[#include <gmp.h>]])
fi
AC_SUBST([SCM_I_GSC_ENABLE_MINI_GMP])
AM_CONDITIONAL([USE_MINI_GMP], [test "x$enable_mini_gmp" = "xyes"])

dnl GNU libunistring is checked for by Gnulib's `libunistring' module.
if test "x$LTLIBUNISTRING" = "x"; then
  AC_MSG_ERROR([GNU libunistring is required, please install it.])
fi

dnl Sloppy check to make sure people aren't trying to use too-old libunistring.
case "$LIBUNISTRING_VERSION" in
  0.9.0 | 0.9.1 | 0.9.2 )
  AC_MSG_ERROR([libunistring too old.  Please install a recent libunistring (>= 0.9.3).])
  ;;
esac

GUILE_LIBUNISTRING_WITH_ICONV_SUPPORT
if test "x$ac_cv_libunistring_with_iconv_support" != "xyes"; then
  AC_MSG_ERROR([No iconv support.  Please recompile libunistring with iconv enabled.])
fi

dnl Libffi is needed to compile Guile's foreign function interface, but its
dnl interface isn't exposed in Guile's API.
PKG_CHECK_MODULES(LIBFFI, libffi)
AC_SUBST(LIBFFI_CFLAGS)
AC_SUBST(LIBFFI_LIBS)

dnl figure out approriate ffi type for size_t
AC_CHECK_SIZEOF(size_t)
AC_CHECK_SIZEOF(ssize_t)
ffi_size_type=uint$(($ac_cv_sizeof_size_t*8))
ffi_ssize_type=sint$(($ac_cv_sizeof_ssize_t*8))
AC_DEFINE_UNQUOTED([ffi_type_size_t], ffi_type_${ffi_size_type}, 
		   [ffi type for size_t])
AC_DEFINE_UNQUOTED([ffi_type_ssize_t], ffi_type_${ffi_ssize_type}, 
		   [ffi type for ssize_t])

dnl i18n tests
#AC_CHECK_HEADERS([libintl.h])
#AC_CHECK_FUNCS(gettext)
#if test $ac_cv_func_gettext = no; then
#   AC_CHECK_LIB(intl, gettext)
#fi
#AC_CHECK_FUNCS([bindtextdomain textdomain])
AM_GNU_GETTEXT([external], [need-ngettext])
AM_GNU_GETTEXT_VERSION([0.18.1])

### Some systems don't declare some functions.  On such systems, we
### need to at least provide our own K&R-style declarations.

### GUILE_FUNC_DECLARED(function, headerfile)

### Check for a declaration of FUNCTION in HEADERFILE; if it is
### not there, #define MISSING_FUNCTION_DECL.
AC_DEFUN([GUILE_FUNC_DECLARED], [
  AC_CACHE_CHECK(for $1 declaration, guile_cv_func_$1_declared,
    AC_EGREP_HEADER($1, $2,
		    guile_cv_func_$1_declared=yes,
		    guile_cv_func_$1_declared=no))
  if test [x$guile_cv_func_]$1[_declared] = xno; then
    AC_DEFINE([MISSING_]translit($1, [a-z], [A-Z])[_DECL], 1,
      [Define if the operating system supplies $1 without declaring it.])
  fi
])

GUILE_FUNC_DECLARED(sleep, unistd.h)
GUILE_FUNC_DECLARED(usleep, unistd.h)

AC_CHECK_DECLS([getlogin, alarm])

AC_CHECK_DECLS([strptime],,,
[#define _GNU_SOURCE /* ask glibc to give strptime prototype */
#include <time.h>])

### On some systems usleep has no return value.  If it does have one,
### we'd like to return it; otherwise, we'll fake it.
AC_CACHE_CHECK([return type of usleep], guile_cv_func_usleep_return_type,
  [AC_EGREP_HEADER(changequote(<, >)<void[ 	]+usleep>changequote([, ]),
                   unistd.h,
		   [guile_cv_func_usleep_return_type=void],
		   [guile_cv_func_usleep_return_type=int])])
case "$guile_cv_func_usleep_return_type" in
  "void" )
    AC_DEFINE([USLEEP_RETURNS_VOID], 1,
      [Define if the system headers declare usleep to return void.])
  ;;
esac

AC_CHECK_HEADER(sys/un.h, have_sys_un_h=1)
if test -n "$have_sys_un_h" ; then
  AC_DEFINE([HAVE_UNIX_DOMAIN_SOCKETS], 1,
    [Define if the system supports Unix-domain (file-domain) sockets.])
fi

AC_CHECK_FUNCS(getrlimit setrlimit)

AC_CHECK_FUNCS(socketpair getgroups setgroups setpwent pause tzset)

AC_CHECK_FUNCS(sethostent   gethostent   endhostent   dnl
               setnetent    getnetent    endnetent    dnl
               setprotoent  getprotoent  endprotoent  dnl
               setservent   getservent   endservent   dnl
               getnetbyaddr getnetbyname dnl
	       inet_lnaof inet_makeaddr inet_netof hstrerror)

AC_CHECK_MEMBERS([struct sockaddr_in.sin_len],,,
[#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include <netinet/in.h>])

AC_MSG_CHECKING(for __libc_stack_end)
AC_CACHE_VAL(guile_cv_have_libc_stack_end,
[AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <stdio.h>
extern char *__libc_stack_end;]],
   [[printf("%p", (char*) __libc_stack_end);]])],
   [guile_cv_have_libc_stack_end=yes],
   [guile_cv_have_libc_stack_end=no])])
AC_MSG_RESULT($guile_cv_have_libc_stack_end)

if test $guile_cv_have_libc_stack_end = yes; then
  AC_DEFINE([HAVE_LIBC_STACK_END], 1,
           [Define if you have the __libc_stack_end variable.])
fi

dnl Some systems do not declare this.  Some systems do declare it, as a
dnl macro.  With cygwin it may be in a DLL.

AC_MSG_CHECKING(whether netdb.h declares h_errno)
AC_CACHE_VAL(guile_cv_have_h_errno,
  [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <netdb.h>]],
                                      [[int a = h_errno;]])],
  [guile_cv_have_h_errno=yes],
  [guile_cv_have_h_errno=no])])
AC_MSG_RESULT($guile_cv_have_h_errno)
if test $guile_cv_have_h_errno = yes; then
  AC_DEFINE([HAVE_H_ERRNO], 1, [Define if h_errno is declared in netdb.h.])
fi

AC_MSG_CHECKING(whether uint32_t is defined)
AC_CACHE_VAL(guile_cv_have_uint32_t,
  [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <sys/types.h>
		   #if HAVE_STDINT_H
		   #include <stdint.h>
                   #endif
		   #ifndef HAVE_NETDB_H
	           #include <netdb.h>
		   #endif]],
		   [[uint32_t a;]])],
		   [guile_cv_have_uint32_t=yes],
		   [guile_cv_have_uint32_t=no])])
AC_MSG_RESULT($guile_cv_have_uint32_t)
if test $guile_cv_have_uint32_t = yes; then
  AC_DEFINE([HAVE_UINT32_T], 1,
    [Define if uint32_t typedef is defined when netdb.h is include.])
fi

AC_MSG_CHECKING(for working IPv6 support)
AC_CACHE_VAL(guile_cv_have_ipv6,
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include <netinet/in.h>
#include <sys/socket.h>]],
[[struct sockaddr_in6 a;  a.sin6_family = AF_INET6;]])],
[guile_cv_have_ipv6=yes],
[guile_cv_have_ipv6=no])])
AC_MSG_RESULT($guile_cv_have_ipv6)
if test $guile_cv_have_ipv6 = yes; then
  AC_DEFINE([HAVE_IPV6], 1, [Define if you want support for IPv6.])
fi

# included in rfc2553 but not in older implementations, e.g., glibc 2.1.3.
AC_MSG_CHECKING(whether sockaddr_in6 has sin6_scope_id)
AC_CACHE_VAL(guile_cv_have_sin6_scope_id,
[AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include <netinet/in.h>]],
[[struct sockaddr_in6 sok;  sok.sin6_scope_id = 0;]])],
[guile_cv_have_sin6_scope_id=yes],
[guile_cv_have_sin6_scope_id=no])])
AC_MSG_RESULT($guile_cv_have_sin6_scope_id)
if test $guile_cv_have_sin6_scope_id = yes; then
  AC_DEFINE([HAVE_SIN6_SCOPE_ID], 1,
    [Define this if your IPv6 has sin6_scope_id in sockaddr_in6 struct.])
fi

# struct sockaddr_in6 field sin_len is only present on BSD systems
AC_CHECK_MEMBERS([struct sockaddr_in6.sin6_len],,,
[#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif
#include <netinet/in.h>])

AC_MSG_CHECKING(whether localtime caches TZ)
AC_CACHE_VAL(guile_cv_localtime_cache,
[if test x$ac_cv_func_tzset = xyes; then
AC_RUN_IFELSE([AC_LANG_SOURCE([[#include <time.h>
#if STDC_HEADERS
# include <stdlib.h>
#endif
extern char **environ;
unset_TZ ()
{
  char **from, **to;
  for (to = from = environ; (*to = *from); from++)
    if (! (to[0][0] == 'T' && to[0][1] == 'Z' && to[0][2] == '='))
      to++;
}
char TZ_GMT0[] = "TZ=GMT0";
char TZ_PST8[] = "TZ=PST8";
main()
{
  time_t now = time ((time_t *) 0);
  int hour_GMT0, hour_unset;
  if (putenv (TZ_GMT0) != 0)
    exit (1);
  hour_GMT0 = localtime (&now)->tm_hour;
  unset_TZ ();
  hour_unset = localtime (&now)->tm_hour;
  if (putenv (TZ_PST8) != 0)
    exit (1);
  if (localtime (&now)->tm_hour == hour_GMT0)
    exit (1);
  unset_TZ ();
  if (localtime (&now)->tm_hour != hour_unset)
    exit (1);
  exit (0);
}]])],
[guile_cv_localtime_cache=no],
[guile_cv_localtime_cache=yes],
[# If we have tzset, assume the worst when cross-compiling.
guile_cv_localtime_cache=yes])
else
        # If we lack tzset, report that localtime does not cache TZ,
        # since we can't invalidate the cache if we don't have tzset.
        guile_cv_localtime_cache=no
fi])dnl
AC_MSG_RESULT($guile_cv_localtime_cache)
if test $guile_cv_localtime_cache = yes; then
  AC_DEFINE([LOCALTIME_CACHE], 1, [Define if localtime caches the TZ setting.])
fi

if test "$enable_regex" = yes; then
   AC_LIBOBJ([regex-posix])
   AC_DEFINE([ENABLE_REGEX], 1, [Define when regex support is enabled.])
fi

if test "$enable_tmpnam" = yes; then
   AC_DEFINE([ENABLE_TMPNAM], 1, [Define when tmpnam support is enabled.])
fi

AC_REPLACE_FUNCS([strerror memmove])

# Reasons for testing:
#   asinh, acosh, atanh, trunc - C99 standard, generally not available on
#                                older systems
#   sincos - GLIBC extension
#   __sincos - APPLE extension
#
AC_CHECK_FUNCS(asinh acosh atanh copysign finite sincos __sincos trunc)

# C99 specifies isinf and isnan as macros.
# HP-UX provides only macros, no functions.
# glibc 2.3.2 provides both macros and functions.
# IRIX 6.5 and Solaris 8 only provide functions.
#
# The following tests detect isinf and isnan either as functions or as
# macros from <math.h>.  Plain AC_CHECK_FUNCS is insufficient, it doesn't
# use <math.h> so doesn't detect on macro-only systems like HP-UX.
#
AC_MSG_CHECKING([for isinf])
AC_LINK_IFELSE([AC_LANG_SOURCE(
[[#include <math.h>
volatile double x = 0.0;
int main () { return (isinf(x) != 0); }]])],
  [AC_MSG_RESULT([yes])
   AC_DEFINE([HAVE_ISINF], 1,
             [Define to 1 if you have the `isinf' macro or function.])],
  [AC_MSG_RESULT([no])])
AC_MSG_CHECKING([for isnan])
AC_LINK_IFELSE([AC_LANG_SOURCE([[
#include <math.h>
volatile double x = 0.0;
int main () { return (isnan(x) != 0); }]])],
  [AC_MSG_RESULT([yes])
   AC_DEFINE([HAVE_ISNAN], 1,
             [Define to 1 if you have the `isnan' macro or function.])],
  [AC_MSG_RESULT([no])])

# Reasons for checking:
#
#     st_rdev
#     st_blksize
#     st_blocks   not in mingw
#     tm_gmtoff   BSD+GNU, not in C99
#
# Note AC_STRUCT_ST_BLOCKS is not used here because we don't want the
# AC_LIBOBJ(fileblocks) replacement which that macro gives.
#
AC_CHECK_MEMBERS([struct stat.st_rdev, struct stat.st_blksize, struct stat.st_blocks, struct stat.st_atim, struct stat.st_mtim, struct stat.st_ctim],,,
                 [#define _GNU_SOURCE
AC_INCLUDES_DEFAULT
])

AC_STRUCT_TIMEZONE
AC_CHECK_MEMBERS([struct tm.tm_gmtoff],,,
[#include <time.h>
#ifdef TIME_WITH_SYS_TIME
# include <sys/time.h>
# include <time.h>
#else
# if HAVE_SYS_TIME_H
#  include <sys/time.h>
# else
#  include <time.h>
# endif
#endif
])
GUILE_STRUCT_UTIMBUF


#--------------------------------------------------------------------
#
# What values do the iconv error handlers have?
#
# The only place that we need iconv in our public interfaces is for
# the error handlers, which are just ints.  So we weaken our
# dependency by looking up those values at configure-time.
#--------------------------------------------------------------------
GUILE_UNISTRING_ICONVEH_VALUES

#--------------------------------------------------------------------
#
# Which way does the stack grow?
#
# Following code comes from Autoconf 2.69's internal _AC_LIBOBJ_ALLOCA
# macro (/usr/share/autoconf/autoconf/functions.m4).  Gnulib has
# very similar code, so in future we could look at using that.
#
# An important detail is that the code involves find_stack_direction
# calling _itself_ - which means that find_stack_direction (or at
# least the second find_stack_direction() call) cannot be inlined.
# If the code could be inlined, that might cause the test to give
# an incorrect answer.
#--------------------------------------------------------------------

SCM_I_GSC_STACK_GROWS_UP=0
AC_RUN_IFELSE([AC_LANG_SOURCE(
[AC_INCLUDES_DEFAULT
int
find_stack_direction (int *addr, int depth)
{
  int dir, dummy = 0;
  if (! addr)
    addr = &dummy;
  *addr = addr < &dummy ? 1 : addr == &dummy ? 0 : -1;
  dir = depth ? find_stack_direction (addr, depth - 1) : 0;
  return dir + dummy;
}

int
main (int argc, char **argv)
{
  return find_stack_direction (0, argc + !argv + 20) < 0;
}])],
	       [SCM_I_GSC_STACK_GROWS_UP=1],
	       [],
	       [AC_MSG_WARN(Guessing that stack grows down -- see scmconfig.h)])

#--------------------------------------------------------------------
#
# Boehm's GC library
#
#--------------------------------------------------------------------
AC_MSG_CHECKING(for which bdw-gc pkg-config file to use)
AC_ARG_WITH(bdw_gc, [  --with-bdw-gc=PKG       name of BDW-GC pkg-config file],
            [bdw_gc="$withval"], [bdw_gc=bdw-gc])
AC_MSG_RESULT($bdw_gc)
PKG_CHECK_MODULES([BDW_GC], [$bdw_gc >= 7.2])

save_LIBS="$LIBS"
LIBS="$BDW_GC_LIBS $LIBS"
CFLAGS="$BDW_GC_CFLAGS $CFLAGS"

# Functions that might not be defined, depending on configuration.
AC_CHECK_FUNCS([GC_pthread_exit GC_pthread_cancel GC_pthread_sigmask])

# Functions from GC 7.3.
AC_CHECK_FUNCS([GC_move_disappearing_link GC_is_heap_ptr])

# See if there's an auxiliary stack, as in ia64.
AC_CHECK_MEMBER([struct GC_stack_base.reg_base],
  [SCM_I_GSC_HAVE_AUXILIARY_STACK=1], [SCM_I_GSC_HAVE_AUXILIARY_STACK=0],
  [#include <gc/gc.h>])
AC_SUBST([SCM_I_GSC_HAVE_AUXILIARY_STACK])

LIBS="$save_LIBS"


AC_CHECK_SIZEOF(float)
if test "$ac_cv_sizeof_float" -le "$ac_cv_sizeof_long"; then
    AC_DEFINE([SCM_SINGLES], 1, 
              [Define this if floats are the same size as longs.])
fi

AC_MSG_CHECKING(for struct linger)
AC_CACHE_VAL(scm_cv_struct_linger,
	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#include <sys/types.h>
#include <sys/socket.h>]],
	                  [[struct linger lgr;  lgr.l_linger = 100]])],
			  [scm_cv_struct_linger="yes"],
			  [scm_cv_struct_linger="no"]))
AC_MSG_RESULT($scm_cv_struct_linger)
if test $scm_cv_struct_linger = yes; then
	AC_DEFINE([HAVE_STRUCT_LINGER], 1,
          [Define this if your system defines struct linger, for use with the
           getsockopt and setsockopt system calls.])
fi


dnl Check for `struct timespec', for the sake of `gen-scmconfig'.  When
dnl building Guile, we always have it, thanks to Gnulib; but scmconfig.h
dnl must tell whether the system has it.
dnl
dnl On MinGW, struct timespec is in <pthread.h>.
AC_MSG_CHECKING(for struct timespec)
AC_CACHE_VAL(scm_cv_struct_timespec,
	AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[
#include <time.h>
#if HAVE_PTHREAD_H
#include <pthread.h>
#endif]], [[struct timespec t;  t.tv_nsec = 100]])],
          [scm_cv_struct_timespec="yes"],
          [scm_cv_struct_timespec="no"]))
AC_MSG_RESULT($scm_cv_struct_timespec)
if test $scm_cv_struct_timespec = yes; then
  dnl Don't call it `HAVE_STRUCT_TIMESPEC' because pthread-win32's
  dnl <pthread.h> checks whether that macro is defined.
  AC_DEFINE([HAVE_SYSTEM_STRUCT_TIMESPEC], 1,
    [Define this if your system defines struct timespec via either <time.h> or <pthread.h>.])
fi

#--------------------------------------------------------------------
#
# Flags for thread support
#
#--------------------------------------------------------------------

SCM_I_GSC_USE_PTHREAD_THREADS=0
SCM_I_GSC_USE_NULL_THREADS=0
AC_SUBST([SCM_I_GSC_USE_PTHREAD_THREADS])
AC_SUBST([SCM_I_GSC_USE_NULL_THREADS])

### What thread package has the user asked for?
AC_ARG_WITH(threads, [  --with-threads          thread interface],
            , with_threads=yes)

AC_SUBST(SCM_I_GSC_NEED_BRACES_ON_PTHREAD_ONCE_INIT, 0)
AC_SUBST(SCM_I_GSC_NEED_BRACES_ON_PTHREAD_MUTEX_INITIALIZER, 0)

case "$with_threads" in
  "yes" | "pthread" | "pthreads" | "pthread-threads" | "")

    build_pthread_support="yes"

    ACX_PTHREAD([CC="$PTHREAD_CC"
       LIBS="$PTHREAD_LIBS $LIBS"
       SCM_I_GSC_USE_PTHREAD_THREADS=1
       with_threads="pthreads"],
      [with_threads="null"
       build_pthread_support="no"])

    old_CFLAGS="$CFLAGS"
    CFLAGS="$PTHREAD_CFLAGS $CFLAGS"

    # Reasons for testing:
    #     pthread_getattr_np - "np" meaning "non portable" says it
    #         all; not present on MacOS X or Solaris 10
    #     pthread_get_stackaddr_np - "np" meaning "non portable" says it
    #         all; specific to MacOS X
    #     pthread_attr_get_np - "np" meaning "non portable" says it
    #         all; specific to FreeBSD
    #     pthread_sigmask - not available on mingw
    #     pthread_cancel - not available on Android (Bionic libc)
    #
    AC_CHECK_FUNCS([pthread_attr_getstack pthread_getattr_np		\
      pthread_get_stackaddr_np pthread_attr_get_np pthread_sigmask	\
      pthread_cancel])

    # On past versions of Solaris, believe 8 through 10 at least, you
    # had to write "pthread_once_t foo = { PTHREAD_ONCE_INIT };".
    # This is contrary to POSIX:
    # http://www.opengroup.org/onlinepubs/000095399/functions/pthread_once.html
    # Check here if this style is required.
    #
    # glibc (2.3.6 at least) works both with or without braces, so the
    # test checks whether it works without.
    #

    if test "$GCC" = "yes"; then
      # Since GCC only issues a warning for missing braces, so we need
      # `-Werror' to catch it.
      CFLAGS="-Werror -Wmissing-braces $CFLAGS"
    fi

    AC_CACHE_CHECK([whether PTHREAD_ONCE_INIT needs braces],
      guile_cv_need_braces_on_pthread_once_init,
      [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <pthread.h>
         pthread_once_t foo = PTHREAD_ONCE_INIT;]])],
        [guile_cv_need_braces_on_pthread_once_init=no],
        [guile_cv_need_braces_on_pthread_once_init=yes])])
    if test "$guile_cv_need_braces_on_pthread_once_init" = yes; then
      SCM_I_GSC_NEED_BRACES_ON_PTHREAD_ONCE_INIT=1
    fi

    # Same problem with `PTHREAD_MUTEX_INITIALIZER', e.g., on IRIX
    # 6.5.30m with GCC 3.3.
    AC_CACHE_CHECK([whether PTHREAD_MUTEX_INITIALIZER needs braces],
      guile_cv_need_braces_on_pthread_mutex_initializer,
      [AC_COMPILE_IFELSE([AC_LANG_PROGRAM([[#include <pthread.h>
         pthread_mutex_t foo = PTHREAD_MUTEX_INITIALIZER;]])],
        [guile_cv_need_braces_on_pthread_mutex_initializer=no],
        [guile_cv_need_braces_on_pthread_mutex_initializer=yes])])
    if test "$guile_cv_need_braces_on_pthread_mutex_initializer" = yes; then
      SCM_I_GSC_NEED_BRACES_ON_PTHREAD_MUTEX_INITIALIZER=1
    fi

    CFLAGS="$old_CFLAGS"

    # On Solaris, sched_yield lives in -lrt.
    AC_SEARCH_LIBS(sched_yield, rt)
    
  ;;
esac

case "$with_threads" in
  "pthreads")
  ;;
  "no" | "null")
    SCM_I_GSC_USE_NULL_THREADS=1
    SCM_I_GSC_HAVE_THREAD_STORAGE_CLASS=0
    with_threads="null-threads"
  ;;
  * )
    AC_MSG_ERROR(invalid value for --with-threads: $with_threads)
  ;;
esac

AC_MSG_CHECKING(what kind of threads to support)
AC_MSG_RESULT($with_threads)

AM_CONDITIONAL([BUILD_PTHREAD_SUPPORT],
  [test "x$build_pthread_support" = "xyes"])


if test "$with_threads" = pthreads; then

dnl Normally Gnulib's 'threadlib' module would define this macro, but
dnl since we don't use it, define it by ourselves.
AC_DEFINE([USE_POSIX_THREADS], [1],
  [Define to let Gnulib modules know that we use POSIX threads.])

AC_MSG_CHECKING([whether pthread_attr_getstack works for the main thread])
old_CFLAGS="$CFLAGS"
CFLAGS="$PTHREAD_CFLAGS $CFLAGS"
if test "$cross_compiling" = "no"; then
  AC_RUN_IFELSE([AC_LANG_SOURCE([[
  #if HAVE_PTHREAD_ATTR_GETSTACK
  #include <pthread.h>

  int main ()
  {
    pthread_attr_t attr;
    void *start, *end;
    size_t size;

    pthread_getattr_np (pthread_self (), &attr);
    pthread_attr_getstack (&attr, &start, &size);
    end = (char *)start + size;

    if ((void *)&attr < start || (void *)&attr >= end)
      return 1;
    else
      return 0;
  }
  #else
  int main ()
  {
    return 1;
  }
  #endif
  ]])],
  [works=yes
   AC_DEFINE([PTHREAD_ATTR_GETSTACK_WORKS], [1], [Define when pthread_att_get_stack works for the main thread])],
  [works=no],
  [])
else
  works="assuming it doesn't"
fi
CFLAGS="$old_CFLAGS"
AC_MSG_RESULT($works)

GUILE_THREAD_LOCAL_STORAGE

fi # with_threads=pthreads


## Cross building	
if test "$cross_compiling" = "yes"; then
  AC_MSG_CHECKING(cc for build)
  ## /usr/bin/cc still uses wrong assembler
  ## CC_FOR_BUILD="${CC_FOR_BUILD-/usr/bincc}"
  CC_FOR_BUILD="${CC_FOR_BUILD-PATH=/usr/bin:$PATH cc}"
else
  CC_FOR_BUILD="${CC_FOR_BUILD-$CC}"
fi   
     
## AC_MSG_CHECKING("if we are cross compiling")
## AC_MSG_RESULT($cross_compiling)
if test "$cross_compiling" = "yes"; then
   AC_MSG_RESULT($CC_FOR_BUILD)
fi

## No need as yet to be more elaborate
CCLD_FOR_BUILD="$CC_FOR_BUILD"

AC_SUBST(cross_compiling)
AC_ARG_VAR(CC_FOR_BUILD,[build system C compiler])
AC_SUBST(CCLD_FOR_BUILD)
	
## libtool erroneously calls CC_FOR_BUILD HOST_CC;
## --HOST is the platform that PACKAGE is compiled for.
HOST_CC="$CC_FOR_BUILD"
AC_SUBST(HOST_CC)

GUILE_CHECK_GUILE_FOR_BUILD
  			
## If we're using GCC, add flags to reduce strictness of undefined
## behavior, and ask for aggressive warnings.
GCC_CFLAGS=""
case "$GCC" in
  yes )
    ## We had -Wstrict-prototypes in here for a bit, but Guile does too
    ## much stuff with generic function pointers for that to really be
    ## less than exasperating.
    ## -Wundef was removed because Gnulib prevented it (see
    ## <http://thread.gmane.org/gmane.lisp.guile.bugs/5329>.)

    ## Build with `-fno-strict-aliasing' and `-fwrapv' to prevent
    ## miscompilation on some platforms.  See
    ## <http://lists.gnu.org/archive/html/guile-devel/2012-01/msg00487.html>.

    POTENTIAL_GCC_CFLAGS="-Wall -Wmissing-prototypes \
      -Wpointer-arith -fno-strict-aliasing -fwrapv"
    # Do this here so we don't screw up any of the tests above that might
    # not be "warning free"
    if test "${GUILE_ERROR_ON_WARNING}" = yes
    then
	POTENTIAL_GCC_CFLAGS="${POTENTIAL_GCC_CFLAGS} -Werror"
	enable_compile_warnings=no
    fi

    for flag in $POTENTIAL_GCC_CFLAGS
    do
	gl_WARN_ADD([$flag], [GCC_CFLAGS])
    done
    ;;
esac

AC_SUBST(GCC_CFLAGS)

# Check for GNU ld's "-z relro".
GUILE_GNU_LD_RELRO


LIBLOBJS=""
for file in $LIBOBJS; do
  file=`echo "$file" | sed 's,\.[[^.]]*$,.lo,'`
  LIBLOBJS="$LIBLOBJS libguile_${GUILE_EFFECTIVE_VERSION}_la-$file"
done

## We also need to create corresponding .doc and .x files
EXTRA_DOT_DOC_FILES="`echo ${LIB@&t@OBJS} | sed 's,\.[[^.]]* ,.doc ,g;s,\.[[^.]]*$,.doc,'`"
EXTRA_DOT_X_FILES="`echo ${LIB@&t@OBJS} | sed 's,\.[[^.]]* ,.x ,g;s,\.[[^.]]*$,.x,'`"

# GNU Readline bindings.
GUILE_READLINE

AC_SUBST(GUILE_MAJOR_VERSION)
AC_SUBST(GUILE_MINOR_VERSION)
AC_SUBST(GUILE_MICRO_VERSION)
AC_SUBST(GUILE_EFFECTIVE_VERSION)
AC_SUBST(GUILE_VERSION)

#######################################################################
# library versioning

AC_SUBST(LIBGUILE_INTERFACE_CURRENT)
AC_SUBST(LIBGUILE_INTERFACE_REVISION)
AC_SUBST(LIBGUILE_INTERFACE_AGE)
AC_SUBST(LIBGUILE_INTERFACE)

AC_SUBST(LIBGUILE_I18N_MAJOR)
AC_SUBST(LIBGUILE_I18N_INTERFACE_CURRENT)
AC_SUBST(LIBGUILE_I18N_INTERFACE_REVISION)
AC_SUBST(LIBGUILE_I18N_INTERFACE_AGE)
AC_SUBST(LIBGUILE_I18N_INTERFACE)


#######################################################################

dnl Tell guile-config what flags guile users should compile and link
dnl with, keeping only `-I' flags from $CPPFLAGS.
GUILE_CFLAGS=""
next_is_includedir=false
for flag in $CPPFLAGS
do
  if $next_is_includedir; then
    GUILE_CFLAGS="$GUILE_CFLAGS -I $flag"
    next_is_includedir=false
  else
    case "$flag" in
      -I)  next_is_includedir=true;;
      -I*) GUILE_CFLAGS="$GUILE_CFLAGS $flag";;
      *)   ;;
    esac
  fi
done

GUILE_CFLAGS="$GUILE_CFLAGS $PTHREAD_CFLAGS"
GUILE_LIBS="$LIBS"

AC_SUBST(GUILE_LIBS)
AC_SUBST(GUILE_CFLAGS)

AC_SUBST(AWK)
AC_SUBST(LIBLOBJS)
AC_SUBST(EXTRA_DOT_DOC_FILES)
AC_SUBST(EXTRA_DOT_X_FILES)

dnl See also top_builddir in info node: (libtool)AC_PROG_LIBTOOL
top_builddir_absolute=`pwd`
AC_SUBST(top_builddir_absolute)
top_srcdir_absolute=`(cd $srcdir && pwd)`
AC_SUBST(top_srcdir_absolute)

dnl Add -I flag so that lib/glthread/lock.h finds <libguile/threads.h>.
CPPFLAGS="-I$top_srcdir_absolute $CPPFLAGS"

dnl `sitedir' goes into libpath.h and the pkg-config file.
pkgdatadir="$datadir/$PACKAGE_TARNAME"
sitedir="$pkgdatadir/site/$GUILE_EFFECTIVE_VERSION"
AC_SUBST([sitedir])

# Additional SCM_I_GSC definitions are above.
AC_SUBST([SCM_I_GSC_GUILE_DEBUG])
AC_SUBST([SCM_I_GSC_ENABLE_DEPRECATED])
AC_SUBST([SCM_I_GSC_STACK_GROWS_UP])
AC_SUBST([SCM_I_GSC_C_INLINE])
AC_CONFIG_FILES([libguile/gen-scmconfig.h])

AC_CONFIG_FILES([
  Makefile
  am/Makefile
  lib/Makefile
  benchmark-suite/Makefile
  gc-benchmarks/Makefile
  doc/Makefile
  doc/r5rs/Makefile
  doc/ref/Makefile
  emacs/Makefile
  examples/Makefile
  libguile/Makefile
  libguile/version.h
  guile-readline/Makefile
  test-suite/Makefile
  test-suite/standalone/Makefile
  meta/Makefile
  module/Makefile
  stage0/Makefile
  stage1/Makefile
  stage2/Makefile
  prebuilt/Makefile
  prebuilt/x86_64-unknown-linux-gnu/Makefile
  prebuilt/i686-pc-linux-gnu/Makefile
  prebuilt/mips-unknown-linux-gnu/Makefile
])


GUILE_CONFIG_SCRIPT([check-guile])
GUILE_CONFIG_SCRIPT([benchmark-guile])
GUILE_CONFIG_SCRIPT([meta/guile])
GUILE_CONFIG_SCRIPT([meta/build-env])
GUILE_CONFIG_SCRIPT([meta/uninstalled-env])
GUILE_CONFIG_SCRIPT([meta/gdb-uninstalled-guile])
GUILE_CONFIG_SCRIPT([libguile/guile-snarf])
GUILE_CONFIG_SCRIPT([libguile/guile-snarf-docs])
GUILE_CONFIG_SCRIPT([test-suite/standalone/test-use-srfi])
GUILE_CONFIG_SCRIPT([test-suite/standalone/test-fast-slot-ref])

AC_OUTPUT

dnl Local Variables:
dnl comment-start: "dnl "
dnl comment-end: ""
dnl comment-start-skip: "\\bdnl\\b\\s *"
dnl End: