glibc/sysdeps/mach/hurd/configure.in

sinclude(./aclocal.m4)dnl Autoconf lossage.
GLIBC_PROVIDES dnl See aclocal.m4 in the top level source directory.

# GNU libc on the Hurd is always reentrant.
DEFINES="$DEFINES -D_LIBC_REENTRANT"

# Don't bother trying to generate any glue code to be compatible with the
# existing system library, because we are the only system library.
inhibit_glue=yes

if test "x$prefix" != x; then
  AC_MSG_WARN([--prefix= (empty) is required for GNU/Hurd to work normally])
fi

case "$machine" in
  i386*)
    # The default oldest ABI is 2.2.6.
    # We only need a "yes" here if the oldest ABI supported will be < 2.2.6.
    if test "$oldest_abi" != default && test "$oldest_abi" \< "2.2.6"; then
      libc_cv_gcc_unwind_find_fde=yes
    fi
    ;;
esac

dnl Swiped from hurd/aclocal.m4
AC_DEFUN([hurd_MIG_RETCODE], [dnl
# See if mig groks `retcode'.
AC_CACHE_CHECK(whether $MIG supports the retcode keyword, hurd_cv_mig_retcode,
[cat > conftest.defs <<\EOF
#include <mach/std_types.defs>
#include <mach/mach_types.defs>
subsystem foobar 1000;
type reply_port_t = polymorphic | MACH_MSG_TYPE_PORT_SEND_ONCE
	ctype: mach_port_t;
simpleroutine foobar_reply (
	reply_port: reply_port_t;
	err: kern_return_t, RetCode);
EOF
if AC_TRY_COMMAND([CC="${CC}" ${MIG-false} -n conftest.defs 1>&AC_FD_CC]); then
  hurd_cv_mig_retcode=yes
else
  hurd_cv_mig_retcode=no
fi
rm -f conftest*])
if test $hurd_cv_mig_retcode = yes; then
  AC_DEFINE(HAVE_MIG_RETCODE)
fi])

hurd_MIG_RETCODE