configure.ac

dnl ***********************************************
dnl * Please run autoreconf to test your changes! *
dnl ***********************************************

# Set VERSION so we only need to edit in one place (i.e., here)
m4_define(PYTHON_VERSION, 3.9)

AC_PREREQ([2.69])

AC_INIT([python],[PYTHON_VERSION],[https://bugs.python.org/])

AC_CONFIG_MACRO_DIR(m4)

AC_SUBST(BASECPPFLAGS)
if test "$srcdir" != . -a "$srcdir" != "$(pwd)"; then
    # If we're building out-of-tree, we need to make sure the following
    # resources get picked up before their $srcdir counterparts.
    #   Objects/ -> typeslots.inc
    #   Include/ -> Python-ast.h, graminit.h
    #   Python/  -> importlib.h
    # (A side effect of this is that these resources will automatically be
    #  regenerated when building out-of-tree, regardless of whether or not
    #  the $srcdir counterpart is up-to-date.  This is an acceptable trade
    #  off.)
    BASECPPFLAGS="-IObjects -IInclude -IPython"
else
    BASECPPFLAGS=""
fi

AC_SUBST(GITVERSION)
AC_SUBST(GITTAG)
AC_SUBST(GITBRANCH)

if test -e $srcdir/.git
then
AC_CHECK_PROG(HAS_GIT, git, found, not-found)
else
HAS_GIT=no-repository
fi
if test $HAS_GIT = found
then
    GITVERSION="git --git-dir \$(srcdir)/.git rev-parse --short HEAD"
    GITTAG="git --git-dir \$(srcdir)/.git describe --all --always --dirty"
    GITBRANCH="git --git-dir \$(srcdir)/.git name-rev --name-only HEAD"
else
    GITVERSION=""
    GITTAG=""
    GITBRANCH=""
fi

AC_CONFIG_SRCDIR([Include/object.h])
AC_CONFIG_HEADER(pyconfig.h)

AC_CANONICAL_HOST
AC_SUBST(build)
AC_SUBST(host)

# pybuilddir.txt will be created by --generate-posix-vars in the Makefile
rm -f pybuilddir.txt

AC_CHECK_PROGS(PYTHON_FOR_REGEN, python$PACKAGE_VERSION python3 python, python3)
AC_SUBST(PYTHON_FOR_REGEN)

if test "$cross_compiling" = yes; then
    AC_MSG_CHECKING([for python interpreter for cross build])
    if test -z "$PYTHON_FOR_BUILD"; then
        for interp in python$PACKAGE_VERSION python3 python; do
	    which $interp >/dev/null 2>&1 || continue
	    if $interp -c "import sys;sys.exit(not '.'.join(str(n) for n in sys.version_info@<:@:2@:>@) == '$PACKAGE_VERSION')"; then
	        break
	    fi
            interp=
	done
        if test x$interp = x; then
	    AC_MSG_ERROR([python$PACKAGE_VERSION interpreter not found])
	fi
        AC_MSG_RESULT($interp)
	PYTHON_FOR_BUILD='_PYTHON_PROJECT_BASE=$(abs_builddir) _PYTHON_HOST_PLATFORM=$(_PYTHON_HOST_PLATFORM) PYTHONPATH=$(shell test -f pybuilddir.txt && echo $(abs_builddir)/`cat pybuilddir.txt`:)$(srcdir)/Lib _PYTHON_SYSCONFIGDATA_NAME=_sysconfigdata_$(ABIFLAGS)_$(MACHDEP)_$(MULTIARCH) '$interp
    fi
elif test "$cross_compiling" = maybe; then
    AC_MSG_ERROR([Cross compiling required --host=HOST-TUPLE and --build=ARCH])
else
    PYTHON_FOR_BUILD='./$(BUILDPYTHON) -E'
fi
AC_SUBST(PYTHON_FOR_BUILD)

dnl Ensure that if prefix is specified, it does not end in a slash. If
dnl it does, we get path names containing '//' which is both ugly and
dnl can cause trouble.

dnl Last slash shouldn't be stripped if prefix=/
if test "$prefix" != "/"; then
    prefix=`echo "$prefix" | sed -e 's/\/$//g'`
fi

dnl This is for stuff that absolutely must end up in pyconfig.h.
dnl Please use pyport.h instead, if possible.
AH_TOP([
#ifndef Py_PYCONFIG_H
#define Py_PYCONFIG_H
])
AH_BOTTOM([
/* Define the macros needed if on a UnixWare 7.x system. */
#if defined(__USLC__) && defined(__SCO_VERSION__)
#define STRICT_SYSV_CURSES /* Don't use ncurses extensions */
#endif

#endif /*Py_PYCONFIG_H*/
])

# We don't use PACKAGE_ variables, and they cause conflicts
# with other autoconf-based packages that include Python.h
grep -v 'define PACKAGE_' <confdefs.h >confdefs.h.new
rm confdefs.h
mv confdefs.h.new confdefs.h

AC_SUBST(VERSION)
VERSION=PYTHON_VERSION

# Version number of Python's own shared library file.
AC_SUBST(SOVERSION)
SOVERSION=1.0

# The later defininition of _XOPEN_SOURCE disables certain features
# on Linux, so we need _GNU_SOURCE to re-enable them (makedev, tm_zone).
AC_DEFINE(_GNU_SOURCE, 1, [Define on Linux to activate all library features])

# The later defininition of _XOPEN_SOURCE and _POSIX_C_SOURCE disables
# certain features on NetBSD, so we need _NETBSD_SOURCE to re-enable
# them.
AC_DEFINE(_NETBSD_SOURCE, 1, [Define on NetBSD to activate all library features])

# The later defininition of _XOPEN_SOURCE and _POSIX_C_SOURCE disables
# certain features on FreeBSD, so we need __BSD_VISIBLE to re-enable
# them.
AC_DEFINE(__BSD_VISIBLE, 1, [Define on FreeBSD to activate all library features])

# The later defininition of _XOPEN_SOURCE and _POSIX_C_SOURCE disables
# certain features on Mac OS X, so we need _DARWIN_C_SOURCE to re-enable
# them.
AC_DEFINE(_DARWIN_C_SOURCE, 1, [Define on Darwin to activate all library features])


define_xopen_source=yes

# Arguments passed to configure.
AC_SUBST(CONFIG_ARGS)
CONFIG_ARGS="$ac_configure_args"

AC_MSG_CHECKING([for --enable-universalsdk])
AC_ARG_ENABLE(universalsdk,
	AS_HELP_STRING([--enable-universalsdk@<:@=SDKDIR@:>@], [Build fat binary against Mac OS X SDK]),
[
	case $enableval in
	yes)
		# Locate the best usable SDK, see Mac/README for more
		# information
		enableval="`/usr/bin/xcodebuild -version -sdk macosx Path 2>/dev/null`"
		if ! ( echo $enableval | grep -E '\.sdk' 1>/dev/null )
		then
			enableval=/Developer/SDKs/MacOSX10.4u.sdk
			if test ! -d "${enableval}"
			then
				enableval=/
			fi
		fi
		;;
	esac
	case $enableval in
	no)
		UNIVERSALSDK=
		enable_universalsdk=
		;;
	*)
		UNIVERSALSDK=$enableval
		if test ! -d "${UNIVERSALSDK}"
		then
			AC_MSG_ERROR([--enable-universalsdk specifies non-existing SDK: ${UNIVERSALSDK}])
		fi
		;;
	esac

],[
   	UNIVERSALSDK=
	enable_universalsdk=
])
if test -n "${UNIVERSALSDK}"
then
	AC_MSG_RESULT(${UNIVERSALSDK})
else
	AC_MSG_RESULT(no)
fi
AC_SUBST(UNIVERSALSDK)

AC_SUBST(ARCH_RUN_32BIT)
ARCH_RUN_32BIT=""

# For backward compatibility reasons we prefer to select '32-bit' if available,
# otherwise use 'intel'
UNIVERSAL_ARCHS="32-bit"
if test "`uname -s`" = "Darwin"
then
	if test -n "${UNIVERSALSDK}"
	then
		if test -z "`/usr/bin/file -L "${UNIVERSALSDK}/usr/lib/libSystem.dylib" | grep ppc`"
		then
			UNIVERSAL_ARCHS="intel"
		fi
	fi
fi

AC_SUBST(LIPO_32BIT_FLAGS)
AC_MSG_CHECKING(for --with-universal-archs)
AC_ARG_WITH(universal-archs,
    AS_HELP_STRING([--with-universal-archs=ARCH], [select architectures for universal build ("32-bit", "64-bit", "3-way", "intel", "intel-32", "intel-64", or "all")]),
[
	UNIVERSAL_ARCHS="$withval"
],
[])
if test -n "${UNIVERSALSDK}"
then
	AC_MSG_RESULT(${UNIVERSAL_ARCHS})
else
	AC_MSG_RESULT(no)
fi

AC_ARG_WITH(framework-name,
              AS_HELP_STRING([--with-framework-name=FRAMEWORK],
                             [specify an alternate name of the framework built with --enable-framework]),
[
    PYTHONFRAMEWORK=${withval}
    PYTHONFRAMEWORKDIR=${withval}.framework
    PYTHONFRAMEWORKIDENTIFIER=org.python.`echo $withval | tr '[A-Z]' '[a-z]'`
    ],[
    PYTHONFRAMEWORK=Python
    PYTHONFRAMEWORKDIR=Python.framework
    PYTHONFRAMEWORKIDENTIFIER=org.python.python
])

AC_ARG_ENABLE(stacklessfewerregisters,
	AC_HELP_STRING(--enable-stacklessfewerregisters, save fewer registers building c-stack switching),
[STACKLESS_FRHACK=1],[ STACKLESS_FRHACK=0 ])
AC_SUBST(STACKLESS_FRHACK)

dnl quadrigraphs "@<:@" and "@:>@" produce "[" and "]" in the output
AC_ARG_ENABLE(framework,
              AS_HELP_STRING([--enable-framework@<:@=INSTALLDIR@:>@], [Build (MacOSX|Darwin) framework]),
[
	case $enableval in
	yes)
		enableval=/Library/Frameworks
	esac
	case $enableval in
	no)
		PYTHONFRAMEWORK=
		PYTHONFRAMEWORKDIR=no-framework
		PYTHONFRAMEWORKPREFIX=
		PYTHONFRAMEWORKINSTALLDIR=
		FRAMEWORKINSTALLFIRST=
		FRAMEWORKINSTALLLAST=
		FRAMEWORKALTINSTALLFIRST=
		FRAMEWORKALTINSTALLLAST=
		FRAMEWORKPYTHONW=
		if test "x${prefix}" = "xNONE"; then
			FRAMEWORKUNIXTOOLSPREFIX="${ac_default_prefix}"
		else
			FRAMEWORKUNIXTOOLSPREFIX="${prefix}"
		fi
		enable_framework=
		;;
	*)
		PYTHONFRAMEWORKPREFIX="${enableval}"
		PYTHONFRAMEWORKINSTALLDIR=$PYTHONFRAMEWORKPREFIX/$PYTHONFRAMEWORKDIR
		FRAMEWORKINSTALLFIRST="frameworkinstallstructure"
		FRAMEWORKALTINSTALLFIRST="frameworkinstallstructure "
		FRAMEWORKINSTALLLAST="frameworkinstallmaclib frameworkinstallapps frameworkinstallunixtools"
		FRAMEWORKALTINSTALLLAST="frameworkinstallmaclib frameworkinstallapps frameworkaltinstallunixtools"
		FRAMEWORKPYTHONW="frameworkpythonw"
		FRAMEWORKINSTALLAPPSPREFIX="/Applications"

		if test "x${prefix}" = "xNONE" ; then
			FRAMEWORKUNIXTOOLSPREFIX="${ac_default_prefix}"

		else
			FRAMEWORKUNIXTOOLSPREFIX="${prefix}"
		fi

		case "${enableval}" in
		/System*)
			FRAMEWORKINSTALLAPPSPREFIX="/Applications"
			if test "${prefix}" = "NONE" ; then
				# See below
				FRAMEWORKUNIXTOOLSPREFIX="/usr"
			fi
			;;

		/Library*)
			FRAMEWORKINSTALLAPPSPREFIX="/Applications"
			;;

		*/Library/Frameworks)
			MDIR="`dirname "${enableval}"`"
			MDIR="`dirname "${MDIR}"`"
			FRAMEWORKINSTALLAPPSPREFIX="${MDIR}/Applications"

			if test "${prefix}" = "NONE"; then
				# User hasn't specified the
				# --prefix option, but wants to install
				# the framework in a non-default location,
				# ensure that the compatibility links get
				# installed relative to that prefix as well
				# instead of in /usr/local.
				FRAMEWORKUNIXTOOLSPREFIX="${MDIR}"
			fi
			;;

		*)
			FRAMEWORKINSTALLAPPSPREFIX="/Applications"
			;;
		esac

		prefix=$PYTHONFRAMEWORKINSTALLDIR/Versions/$VERSION

		# Add files for Mac specific code to the list of output
		# files:
		AC_CONFIG_FILES(Mac/Makefile)
		AC_CONFIG_FILES(Mac/PythonLauncher/Makefile)
		AC_CONFIG_FILES(Mac/Resources/framework/Info.plist)
		AC_CONFIG_FILES(Mac/Resources/app/Info.plist)
	esac
	],[
	PYTHONFRAMEWORK=
	PYTHONFRAMEWORKDIR=no-framework
	PYTHONFRAMEWORKPREFIX=
	PYTHONFRAMEWORKINSTALLDIR=
	FRAMEWORKINSTALLFIRST=
	FRAMEWORKINSTALLLAST=
	FRAMEWORKALTINSTALLFIRST=
	FRAMEWORKALTINSTALLLAST=
	FRAMEWORKPYTHONW=
	if test "x${prefix}" = "xNONE" ; then
		FRAMEWORKUNIXTOOLSPREFIX="${ac_default_prefix}"
	else
		FRAMEWORKUNIXTOOLSPREFIX="${prefix}"
	fi
	enable_framework=

])
AC_SUBST(PYTHONFRAMEWORK)
AC_SUBST(PYTHONFRAMEWORKIDENTIFIER)
AC_SUBST(PYTHONFRAMEWORKDIR)
AC_SUBST(PYTHONFRAMEWORKPREFIX)
AC_SUBST(PYTHONFRAMEWORKINSTALLDIR)
AC_SUBST(FRAMEWORKINSTALLFIRST)
AC_SUBST(FRAMEWORKINSTALLLAST)
AC_SUBST(FRAMEWORKALTINSTALLFIRST)
AC_SUBST(FRAMEWORKALTINSTALLLAST)
AC_SUBST(FRAMEWORKPYTHONW)
AC_SUBST(FRAMEWORKUNIXTOOLSPREFIX)
AC_SUBST(FRAMEWORKINSTALLAPPSPREFIX)

AC_DEFINE_UNQUOTED(_PYTHONFRAMEWORK, "${PYTHONFRAMEWORK}", [framework name])

##AC_ARG_WITH(dyld,
##            AS_HELP_STRING([--with-dyld],
##                           [Use (OpenStep|Rhapsody) dynamic linker]))
##
# Set name for machine-dependent library files
AC_ARG_VAR([MACHDEP], [name for machine-dependent library files])
AC_MSG_CHECKING(MACHDEP)
if test -z "$MACHDEP"
then
    # avoid using uname for cross builds
    if test "$cross_compiling" = yes; then
       # ac_sys_system and ac_sys_release are used for setting
       # a lot of different things including 'define_xopen_source'
       # in the case statement below.
	case "$host" in
	*-*-linux-android*)
		ac_sys_system=Linux-android
		;;
	*-*-linux*)
		ac_sys_system=Linux
		;;
	*-*-cygwin*)
		ac_sys_system=Cygwin
		;;
	*-*-vxworks*)
	    ac_sys_system=VxWorks
	    ;;
	*)
		# for now, limit cross builds to known configurations
		MACHDEP="unknown"
		AC_MSG_ERROR([cross build not supported for $host])
	esac
	ac_sys_release=
    else
	ac_sys_system=`uname -s`
	if test "$ac_sys_system" = "AIX" \
	-o "$ac_sys_system" = "UnixWare" -o "$ac_sys_system" = "OpenUNIX"; then
		ac_sys_release=`uname -v`
	else
		ac_sys_release=`uname -r`
	fi
    fi
    ac_md_system=`echo $ac_sys_system |
			tr -d '[/ ]' | tr '[[A-Z]]' '[[a-z]]'`
    ac_md_release=`echo $ac_sys_release |
			tr -d '[/ ]' | sed 's/^[[A-Z]]\.//' | sed 's/\..*//'`
    MACHDEP="$ac_md_system$ac_md_release"

    case $MACHDEP in
	aix*) MACHDEP="aix";;
	linux*) MACHDEP="linux";;
	cygwin*) MACHDEP="cygwin";;
	darwin*) MACHDEP="darwin";;
	'')	MACHDEP="unknown";;
    esac
fi
AC_MSG_RESULT("$MACHDEP")

AC_SUBST(_PYTHON_HOST_PLATFORM)
if test "$cross_compiling" = yes; then
	case "$host" in
	*-*-linux*)
		case "$host_cpu" in
		arm*)
			_host_cpu=arm
			;;
		*)
			_host_cpu=$host_cpu
		esac
		;;
	*-*-cygwin*)
		_host_cpu=
		;;
	*-*-vxworks*)
		_host_cpu=$host_cpu
		;;
	*)
		# for now, limit cross builds to known configurations
		MACHDEP="unknown"
		AC_MSG_ERROR([cross build not supported for $host])
	esac
	_PYTHON_HOST_PLATFORM="$MACHDEP${_host_cpu:+-$_host_cpu}"
fi

# Some systems cannot stand _XOPEN_SOURCE being defined at all; they
# disable features if it is defined, without any means to access these
# features as extensions. For these systems, we skip the definition of
# _XOPEN_SOURCE. Before adding a system to the list to gain access to
# some feature, make sure there is no alternative way to access this
# feature. Also, when using wildcards, make sure you have verified the
# need for not defining _XOPEN_SOURCE on all systems matching the
# wildcard, and that the wildcard does not include future systems
# (which may remove their limitations).
dnl quadrigraphs "@<:@" and "@:>@" produce "[" and "]" in the output
case $ac_sys_system/$ac_sys_release in
  # On OpenBSD, select(2) is not available if _XOPEN_SOURCE is defined,
  # even though select is a POSIX function. Reported by J. Ribbens.
  # Reconfirmed for OpenBSD 3.3 by Zachary Hamm, for 3.4 by Jason Ish.
  # In addition, Stefan Krah confirms that issue #1244610 exists through
  # OpenBSD 4.6, but is fixed in 4.7.
  OpenBSD/2.* | OpenBSD/3.* | OpenBSD/4.@<:@0123456@:>@)
    define_xopen_source=no
    # OpenBSD undoes our definition of __BSD_VISIBLE if _XOPEN_SOURCE is
    # also defined. This can be overridden by defining _BSD_SOURCE
    # As this has a different meaning on Linux, only define it on OpenBSD
    AC_DEFINE(_BSD_SOURCE, 1, [Define on OpenBSD to activate all library features])
    ;;
  OpenBSD/*)
    # OpenBSD undoes our definition of __BSD_VISIBLE if _XOPEN_SOURCE is
    # also defined. This can be overridden by defining _BSD_SOURCE
    # As this has a different meaning on Linux, only define it on OpenBSD
    AC_DEFINE(_BSD_SOURCE, 1, [Define on OpenBSD to activate all library features])
    ;;
  # Defining _XOPEN_SOURCE on NetBSD version prior to the introduction of
  # _NETBSD_SOURCE disables certain features (eg. setgroups). Reported by
  # Marc Recht
  NetBSD/1.5 | NetBSD/1.5.* | NetBSD/1.6 | NetBSD/1.6.* | NetBSD/1.6@<:@A-S@:>@)
    define_xopen_source=no;;
  # From the perspective of Solaris, _XOPEN_SOURCE is not so much a
  # request to enable features supported by the standard as a request
  # to disable features not supported by the standard.  The best way
  # for Python to use Solaris is simply to leave _XOPEN_SOURCE out
  # entirely and define __EXTENSIONS__ instead.
  SunOS/*)
    define_xopen_source=no;;
  # On UnixWare 7, u_long is never defined with _XOPEN_SOURCE,
  # but used in /usr/include/netinet/tcp.h. Reported by Tim Rice.
  # Reconfirmed for 7.1.4 by Martin v. Loewis.
  OpenUNIX/8.0.0| UnixWare/7.1.@<:@0-4@:>@)
    define_xopen_source=no;;
  # On OpenServer 5, u_short is never defined with _XOPEN_SOURCE,
  # but used in struct sockaddr.sa_family. Reported by Tim Rice.
  SCO_SV/3.2)
    define_xopen_source=no;;
  # On MacOS X 10.2, a bug in ncurses.h means that it craps out if
  # _XOPEN_EXTENDED_SOURCE is defined. Apparently, this is fixed in 10.3, which
  # identifies itself as Darwin/7.*
  # On Mac OS X 10.4, defining _POSIX_C_SOURCE or _XOPEN_SOURCE
  # disables platform specific features beyond repair.
  # On Mac OS X 10.3, defining _POSIX_C_SOURCE or _XOPEN_SOURCE
  # has no effect, don't bother defining them
  Darwin/@<:@6789@:>@.*)
    define_xopen_source=no;;
  Darwin/1@<:@0-9@:>@.*)
    define_xopen_source=no;;
  # On AIX 4 and 5.1, mbstate_t is defined only when _XOPEN_SOURCE == 500 but
  # used in wcsnrtombs() and mbsnrtowcs() even if _XOPEN_SOURCE is not defined
  # or has another value. By not (re)defining it, the defaults come in place.
  AIX/4)
    define_xopen_source=no;;
  AIX/5)
    if test `uname -r` -eq 1; then
      define_xopen_source=no
    fi
    ;;
  # On QNX 6.3.2, defining _XOPEN_SOURCE prevents netdb.h from
  # defining NI_NUMERICHOST.
  QNX/6.3.2)
    define_xopen_source=no
    ;;
  # On VxWorks, defining _XOPEN_SOURCE causes compile failures
  # in network headers still using system V types.
  VxWorks/*)
    define_xopen_source=no
    ;;

esac

if test $define_xopen_source = yes
then
  # X/Open 7, incorporating POSIX.1-2008
  AC_DEFINE(_XOPEN_SOURCE, 700,
            Define to the level of X/Open that your system supports)

  # On Tru64 Unix 4.0F, defining _XOPEN_SOURCE also requires
  # definition of _XOPEN_SOURCE_EXTENDED and _POSIX_C_SOURCE, or else
  # several APIs are not declared. Since this is also needed in some
  # cases for HP-UX, we define it globally.
  AC_DEFINE(_XOPEN_SOURCE_EXTENDED, 1,
   	    Define to activate Unix95-and-earlier features)

  AC_DEFINE(_POSIX_C_SOURCE, 200809L, Define to activate features from IEEE Stds 1003.1-2008)
fi

# On HP-UX mbstate_t requires _INCLUDE__STDC_A1_SOURCE
case $ac_sys_system in
  hp*|HP*)
    define_stdc_a1=yes;;
  *)
    define_stdc_a1=no;;
esac

if test $define_stdc_a1 = yes
then
  AC_DEFINE(_INCLUDE__STDC_A1_SOURCE, 1, Define to include mbstate_t for mbrtowc)
fi

# Record the configure-time value of MACOSX_DEPLOYMENT_TARGET,
# it may influence the way we can build extensions, so distutils
# needs to check it
AC_SUBST(CONFIGURE_MACOSX_DEPLOYMENT_TARGET)
AC_SUBST(EXPORT_MACOSX_DEPLOYMENT_TARGET)
CONFIGURE_MACOSX_DEPLOYMENT_TARGET=
EXPORT_MACOSX_DEPLOYMENT_TARGET='#'

# checks for alternative programs

# compiler flags are generated in two sets, BASECFLAGS and OPT.  OPT is just
# for debug/optimization stuff.  BASECFLAGS is for flags that are required
# just to get things to compile and link.  Users are free to override OPT
# when running configure or make.  The build should not break if they do.
# BASECFLAGS should generally not be messed with, however.

# If the user switches compilers, we can't believe the cache
if test ! -z "$ac_cv_prog_CC" -a ! -z "$CC" -a "$CC" != "$ac_cv_prog_CC"
then
  AC_MSG_ERROR([cached CC is different -- throw away $cache_file
(it is also a good idea to do 'make clean' before compiling)])
fi

# Don't let AC_PROG_CC set the default CFLAGS. It normally sets -g -O2
# when the compiler supports them, but we don't always want -O2, and
# we set -g later.
if test -z "$CFLAGS"; then
        CFLAGS=
fi

if test "$ac_sys_system" = "Darwin"
then
	# Compiler selection on MacOSX is more complicated than
	# AC_PROG_CC can handle, see Mac/README for more
	# information
	if test -z "${CC}"
	then
		found_gcc=
		found_clang=
		as_save_IFS=$IFS; IFS=:
		for as_dir in $PATH
		do
			IFS=$as_save_IFS
			if test -x "${as_dir}/gcc"; then
				if test -z "${found_gcc}"; then
					found_gcc="${as_dir}/gcc"
				fi
			fi
			if test -x "${as_dir}/clang"; then
				if test -z "${found_clang}"; then
					found_clang="${as_dir}/clang"
				fi
			fi
		done
		IFS=$as_save_IFS

		if test -n "$found_gcc" -a -n "$found_clang"
		then
			if test -n "`"$found_gcc" --version | grep llvm-gcc`"
			then
				AC_MSG_NOTICE([Detected llvm-gcc, falling back to clang])
				CC="$found_clang"
				CXX="$found_clang++"
			fi


		elif test -z "$found_gcc" -a -n "$found_clang"
		then
			AC_MSG_NOTICE([No GCC found, use CLANG])
			CC="$found_clang"
			CXX="$found_clang++"

		elif test -z "$found_gcc" -a -z "$found_clang"
		then
			found_clang=`/usr/bin/xcrun -find clang 2>/dev/null`
			if test -n "${found_clang}"
			then
				AC_MSG_NOTICE([Using clang from Xcode.app])
				CC="${found_clang}"
				CXX="`/usr/bin/xcrun -find clang++`"

			# else: use default behaviour
			fi
		fi
	fi
fi
AC_PROG_CC
AC_PROG_CPP
AC_PROG_GREP
AC_PROG_SED

AC_SUBST(CXX)
AC_SUBST(MAINCC)
AC_MSG_CHECKING(for --with-cxx-main=<compiler>)
AC_ARG_WITH(cxx_main,
            AS_HELP_STRING([--with-cxx-main=<compiler>],
                           [compile main() and link python executable with C++ compiler]),
[

	case $withval in
	no)	with_cxx_main=no
		MAINCC='$(CC)';;
	yes)	with_cxx_main=yes
		MAINCC='$(CXX)';;
	*)	with_cxx_main=yes
		MAINCC=$withval
		if test -z "$CXX"
		then
			CXX=$withval
		fi;;
	esac], [
	with_cxx_main=no
	MAINCC='$(CC)'
])
AC_MSG_RESULT($with_cxx_main)

preset_cxx="$CXX"
if test -z "$CXX"
then
        case "$CC" in
        gcc)    AC_PATH_TOOL(CXX, [g++], [g++], [notfound]) ;;
        cc)     AC_PATH_TOOL(CXX, [c++], [c++], [notfound]) ;;
        clang|*/clang)     AC_PATH_TOOL(CXX, [clang++], [clang++], [notfound]) ;;
        icc|*/icc)         AC_PATH_TOOL(CXX, [icpc], [icpc], [notfound]) ;;
        esac
	if test "$CXX" = "notfound"
	then
		CXX=""
	fi
fi
if test -z "$CXX"
then
	AC_CHECK_TOOLS(CXX, $CCC c++ g++ gcc CC cxx cc++ cl, notfound)
	if test "$CXX" = "notfound"
	then
		CXX=""
	fi
fi
if test "$preset_cxx" != "$CXX"
then
        AC_MSG_NOTICE([

  By default, distutils will build C++ extension modules with "$CXX".
  If this is not intended, then set CXX on the configure command line.
  ])
fi


MULTIARCH=$($CC --print-multiarch 2>/dev/null)
AC_SUBST(MULTIARCH)

AC_MSG_CHECKING([for the platform triplet based on compiler characteristics])
cat >> conftest.c <<EOF
#undef bfin
#undef cris
#undef fr30
#undef linux
#undef hppa
#undef hpux
#undef i386
#undef mips
#undef powerpc
#undef sparc
#undef unix
#if defined(__ANDROID__)
    # Android is not a multiarch system.
#elif defined(__linux__)
# if defined(__x86_64__) && defined(__LP64__)
        x86_64-linux-gnu
# elif defined(__x86_64__) && defined(__ILP32__)
        x86_64-linux-gnux32
# elif defined(__i386__)
        i386-linux-gnu
# elif defined(__aarch64__) && defined(__AARCH64EL__)
#  if defined(__ILP32__)
        aarch64_ilp32-linux-gnu
#  else
        aarch64-linux-gnu
#  endif
# elif defined(__aarch64__) && defined(__AARCH64EB__)
#  if defined(__ILP32__)
        aarch64_be_ilp32-linux-gnu
#  else
        aarch64_be-linux-gnu
#  endif
# elif defined(__alpha__)
        alpha-linux-gnu
# elif defined(__ARM_EABI__) && defined(__ARM_PCS_VFP)
#  if defined(__ARMEL__)
        arm-linux-gnueabihf
#  else
        armeb-linux-gnueabihf
#  endif
# elif defined(__ARM_EABI__) && !defined(__ARM_PCS_VFP)
#  if defined(__ARMEL__)
        arm-linux-gnueabi
#  else
        armeb-linux-gnueabi
#  endif
# elif defined(__hppa__)
        hppa-linux-gnu
# elif defined(__ia64__)
        ia64-linux-gnu
# elif defined(__m68k__) && !defined(__mcoldfire__)
        m68k-linux-gnu
# elif defined(__mips_hard_float) && defined(__mips_isa_rev) && (__mips_isa_rev >=6) && defined(_MIPSEL)
#  if _MIPS_SIM == _ABIO32
        mipsisa32r6el-linux-gnu
#  elif _MIPS_SIM == _ABIN32
        mipsisa64r6el-linux-gnuabin32
#  elif _MIPS_SIM == _ABI64
        mipsisa64r6el-linux-gnuabi64
#  else
#   error unknown platform triplet
#  endif
# elif defined(__mips_hard_float) && defined(__mips_isa_rev) && (__mips_isa_rev >=6)
#  if _MIPS_SIM == _ABIO32
        mipsisa32r6-linux-gnu
#  elif _MIPS_SIM == _ABIN32
        mipsisa64r6-linux-gnuabin32
#  elif _MIPS_SIM == _ABI64
        mipsisa64r6-linux-gnuabi64
#  else
#   error unknown platform triplet
#  endif
# elif defined(__mips_hard_float) && defined(_MIPSEL)
#  if _MIPS_SIM == _ABIO32
        mipsel-linux-gnu
#  elif _MIPS_SIM == _ABIN32
        mips64el-linux-gnuabin32
#  elif _MIPS_SIM == _ABI64
        mips64el-linux-gnuabi64
#  else
#   error unknown platform triplet
#  endif
# elif defined(__mips_hard_float)
#  if _MIPS_SIM == _ABIO32
        mips-linux-gnu
#  elif _MIPS_SIM == _ABIN32
        mips64-linux-gnuabin32
#  elif _MIPS_SIM == _ABI64
        mips64-linux-gnuabi64
#  else
#   error unknown platform triplet
#  endif
# elif defined(__or1k__)
        or1k-linux-gnu
# elif defined(__powerpc__) && defined(__SPE__)
        powerpc-linux-gnuspe
# elif defined(__powerpc64__)
#  if defined(__LITTLE_ENDIAN__)
        powerpc64le-linux-gnu
#  else
        powerpc64-linux-gnu
#  endif
# elif defined(__powerpc__)
        powerpc-linux-gnu
# elif defined(__s390x__)
        s390x-linux-gnu
# elif defined(__s390__)
        s390-linux-gnu
# elif defined(__sh__) && defined(__LITTLE_ENDIAN__)
        sh4-linux-gnu
# elif defined(__sparc__) && defined(__arch64__)
        sparc64-linux-gnu
# elif defined(__sparc__)
        sparc-linux-gnu
# elif defined(__riscv)
#  if __riscv_xlen == 32
        riscv32-linux-gnu
#  elif __riscv_xlen == 64
        riscv64-linux-gnu
#  else
#   error unknown platform triplet
#  endif
# else
#   error unknown platform triplet
# endif
#elif defined(__FreeBSD_kernel__)
# if defined(__LP64__)
        x86_64-kfreebsd-gnu
# elif defined(__i386__)
        i386-kfreebsd-gnu
# else
#   error unknown platform triplet
# endif
#elif defined(__gnu_hurd__)
        i386-gnu
#elif defined(__APPLE__)
        darwin
#elif defined(__VXWORKS__)
        vxworks
#else
# error unknown platform triplet
#endif

EOF

if $CPP $CPPFLAGS conftest.c >conftest.out 2>/dev/null; then
  PLATFORM_TRIPLET=`grep -v '^#' conftest.out | grep -v '^ *$' | tr -d ' 	'`
  AC_MSG_RESULT([$PLATFORM_TRIPLET])
else
  AC_MSG_RESULT([none])
fi
rm -f conftest.c conftest.out

if test x$PLATFORM_TRIPLET != x && test x$MULTIARCH != x; then
  if test x$PLATFORM_TRIPLET != x$MULTIARCH; then
    AC_MSG_ERROR([internal configure error for the platform triplet, please file a bug report])
  fi
elif test x$PLATFORM_TRIPLET != x && test x$MULTIARCH = x; then
  MULTIARCH=$PLATFORM_TRIPLET
fi
AC_SUBST(PLATFORM_TRIPLET)
if test x$MULTIARCH != x; then
  MULTIARCH_CPPFLAGS="-DMULTIARCH=\\\"$MULTIARCH\\\""
fi
AC_SUBST(MULTIARCH_CPPFLAGS)

AC_MSG_CHECKING([for -Wl,--no-as-needed])
save_LDFLAGS="$LDFLAGS"
LDFLAGS="$LDFLAGS -Wl,--no-as-needed"
AC_LINK_IFELSE([AC_LANG_PROGRAM([[]], [[]])],
  [NO_AS_NEEDED="-Wl,--no-as-needed"
   AC_MSG_RESULT([yes])],
  [NO_AS_NEEDED=""
   AC_MSG_RESULT([no])])
LDFLAGS="$save_LDFLAGS"
AC_SUBST(NO_AS_NEEDED)


# checks for UNIX variants that set C preprocessor variables
AC_USE_SYSTEM_EXTENSIONS

AC_MSG_CHECKING([for the Android API level])
cat >> conftest.c <<EOF
#ifdef __ANDROID__
android_api = __ANDROID_API__
arm_arch = __ARM_ARCH
#else
#error not Android
#endif
EOF

if $CPP $CPPFLAGS conftest.c >conftest.out 2>/dev/null; then
  ANDROID_API_LEVEL=`sed -n -e '/__ANDROID_API__/d' -e 's/^android_api = //p' conftest.out`
  _arm_arch=`sed -n -e '/__ARM_ARCH/d' -e 's/^arm_arch = //p' conftest.out`
  AC_MSG_RESULT([$ANDROID_API_LEVEL])
  if test -z "$ANDROID_API_LEVEL"; then
    echo 'Fatal: you must define __ANDROID_API__'
    exit 1
  fi
  AC_DEFINE_UNQUOTED(ANDROID_API_LEVEL, $ANDROID_API_LEVEL, [The Android API level.])

  AC_MSG_CHECKING([for the Android arm ABI])
  AC_MSG_RESULT([$_arm_arch])
  if test "$_arm_arch" = 7; then
    BASECFLAGS="${BASECFLAGS} -mfloat-abi=softfp -mfpu=vfpv3-d16"
    LDFLAGS="${LDFLAGS} -march=armv7-a -Wl,--fix-cortex-a8"
  fi
else
  AC_MSG_RESULT([not Android])
fi
rm -f conftest.c conftest.out

# Check for unsupported systems
case $ac_sys_system/$ac_sys_release in
atheos*|Linux*/1*)
   echo This system \($ac_sys_system/$ac_sys_release\) is no longer supported.
   echo See README for details.
   exit 1;;
esac

AC_EXEEXT
AC_MSG_CHECKING(for --with-suffix)
AC_ARG_WITH(suffix,
            AS_HELP_STRING([--with-suffix=.exe], [set executable suffix]),
[
	case $withval in
	no)	EXEEXT=;;
	yes)	EXEEXT=.exe;;
	*)	EXEEXT=$withval;;
	esac])
AC_MSG_RESULT($EXEEXT)

# Test whether we're running on a non-case-sensitive system, in which
# case we give a warning if no ext is given
AC_SUBST(BUILDEXEEXT)
AC_MSG_CHECKING(for case-insensitive build directory)
if test ! -d CaseSensitiveTestDir; then
mkdir CaseSensitiveTestDir
fi

if test -d casesensitivetestdir
then
    AC_MSG_RESULT(yes)
    BUILDEXEEXT=.exe
else
	AC_MSG_RESULT(no)
	BUILDEXEEXT=$EXEEXT
fi
rmdir CaseSensitiveTestDir

case $ac_sys_system in
hp*|HP*)
    case $CC in
    cc|*/cc) CC="$CC -Ae";;
    esac;;
esac

AC_SUBST(LIBRARY)
AC_MSG_CHECKING(LIBRARY)
if test -z "$LIBRARY"
then
	LIBRARY='libpython$(VERSION)$(ABIFLAGS).a'
fi
AC_MSG_RESULT($LIBRARY)

# LDLIBRARY is the name of the library to link against (as opposed to the
# name of the library into which to insert object files). BLDLIBRARY is also
# the library to link against, usually. On Mac OS X frameworks, BLDLIBRARY
# is blank as the main program is not linked directly against LDLIBRARY.
# LDLIBRARYDIR is the path to LDLIBRARY, which is made in a subdirectory. On
# systems without shared libraries, LDLIBRARY is the same as LIBRARY
# (defined in the Makefiles). On Cygwin LDLIBRARY is the import library,
# DLLLIBRARY is the shared (i.e., DLL) library.
#
# RUNSHARED is used to run shared python without installed libraries
#
# INSTSONAME is the name of the shared library that will be use to install
# on the system - some systems like version suffix, others don't
#
# LDVERSION is the shared library version number, normally the Python version
# with the ABI build flags appended.
AC_SUBST(LDLIBRARY)
AC_SUBST(DLLLIBRARY)
AC_SUBST(BLDLIBRARY)
AC_SUBST(PY3LIBRARY)
AC_SUBST(LDLIBRARYDIR)
AC_SUBST(INSTSONAME)