configure.ac

       ;;
  *)   AC_MSG_RESULT(yes)

       if test "x$IPV6_ENABLED" = "x1"; then
         AC_MSG_NOTICE([ares may not work properly with ipv6])
       fi

       AC_DEFINE(USE_ARES, 1, [Define if you want to enable ares support])
       dnl substitute HAVE_ARES for curl-config and similar
       HAVE_ARES="1"
       AC_SUBST(HAVE_ARES)
       curl_ares_msg="enabled"

       LIBS="-lcares $LIBS"

       dnl For backwards compatibility default to includes/lib in srcdir/ares
       dnl If a value is specified it is assumed that the libs are in $val/lib
       dnl and the includes are in $val/include. This is the default setup for
       dnl ares so it should not be a problem.
       if test "x$enableval" = "xyes" ; then
         if test -d "$srcdir/ares"; then
            aresembedded="yes"
            AC_CONFIG_SUBDIRS(ares)
            aresinc=`cd $srcdir/ares && pwd`
            CPPFLAGS="$CPPFLAGS -I$aresinc"

            dnl the pwd= below cannot 'cd' into the ares dir to get the full
            dnl path to it, since it may not exist yet if we build outside of
            dnl the source tree
            pwd=`pwd`
            LDFLAGS="$LDFLAGS -L$pwd/ares"
         fi
       else
         CPPFLAGS="$CPPFLAGS -I$enableval/include"
         LDFLAGS="$LDFLAGS -L$enableval/lib"
       fi

       if test -z "$aresembedded"; then
         dnl verify that a sufficient c-ares is here if we have pointed one
         dnl out and don't use the "embedded" ares dir (in which case we don't
         dnl check it because it might not have been built yet)
         AC_MSG_CHECKING([that c-ares is good and recent enough])
         AC_LINK_IFELSE( [
#include <ares.h>
/* provide a set of dummy functions in case c-ares was built with debug */
void curl_dofree() { }
void curl_sclose() { }
void curl_domalloc() { }

int main(void)
{
  ares_channel channel;
  ares_cancel(channel);
  return 0;
}
],
          AC_MSG_RESULT(yes),
          AC_MSG_RESULT(no)
          AC_MSG_ERROR([c-ares library defective or too old])
          )
       fi
       ;;
  esac ],
       AC_MSG_RESULT(no)
)

dnl ************************************************************
dnl disable verbose text strings
dnl
AC_MSG_CHECKING([whether to enable verbose strings])
AC_ARG_ENABLE(verbose,
AC_HELP_STRING([--enable-verbose],[Enable verbose strings])
AC_HELP_STRING([--disable-verbose],[Disable verbose strings]),
[ case "$enableval" in
  no)
       AC_MSG_RESULT(no)
       AC_DEFINE(CURL_DISABLE_VERBOSE_STRINGS, 1, [to disable verbose strings])
       AC_SUBST(CURL_DISABLE_VERBOSE_STRINGS)
       curl_verbose_msg="no"
       ;;
  *)   AC_MSG_RESULT(yes)
       ;;
  esac ],
       AC_MSG_RESULT(yes)
)

dnl ************************************************************
dnl enable SSPI support
dnl
AC_MSG_CHECKING([whether to enable SSPI support (win32 builds only)])
AC_ARG_ENABLE(sspi,
AC_HELP_STRING([--enable-sspi],[Enable SSPI])
AC_HELP_STRING([--disable-sspi],[Disable SSPI]),
[ case "$enableval" in
  yes)
       AC_MSG_RESULT(yes)
       AC_DEFINE(USE_WINDOWS_SSPI, 1, [to enable SSPI support])
       AC_SUBST(USE_WINDOWS_SSPI)
       curl_sspi_msg="yes"
       ;;
  *)
       AC_MSG_RESULT(no)
       ;;
  esac ],
       AC_MSG_RESULT(no)
)

dnl ************************************************************
dnl lame option to switch on debug options
dnl
AC_MSG_CHECKING([whether to enable debug options])
AC_ARG_ENABLE(debug,
AC_HELP_STRING([--enable-debug],[Enable pedantic debug options])
AC_HELP_STRING([--disable-debug],[Disable debug options]),
[ case "$enableval" in
  no)
       AC_MSG_RESULT(no)
       ;;
  *)   AC_MSG_RESULT(yes)

    CPPFLAGS="$CPPFLAGS -DCURLDEBUG"
    CFLAGS="$CFLAGS -g"

    dnl set compiler "debug" options to become more picky, and remove
    dnl optimize options from CFLAGS
    CURL_CC_DEBUG_OPTS
       ;;
  esac
 ],
       AC_MSG_RESULT(no)
)

dnl ************************************************************
dnl disable cryptographic authentication
dnl
AC_MSG_CHECKING([whether to enable cryptographic authentication methods])
AC_ARG_ENABLE(crypto-auth,
AC_HELP_STRING([--enable-crypto-auth],[Enable cryptographic authentication])
AC_HELP_STRING([--disable-crypto-auth],[Disable cryptographic authentication]),
[ case "$enableval" in
  no)
       AC_MSG_RESULT(no)
       AC_DEFINE(CURL_DISABLE_CRYPTO_AUTH, 1, [to disable cryptographic authentication])
       AC_SUBST(CURL_DISABLE_CRYPTO_AUTH)
       ;;
  *)   AC_MSG_RESULT(yes)
       ;;
  esac ],
       AC_MSG_RESULT(yes)
)

dnl ************************************************************
dnl disable cookies support
dnl
AC_MSG_CHECKING([whether to enable support for cookies])
AC_ARG_ENABLE(cookies,
AC_HELP_STRING([--enable-cookies],[Enable cookies support])
AC_HELP_STRING([--disable-cookies],[Disable cookies support]),
[ case "$enableval" in
  no)
       AC_MSG_RESULT(no)
       AC_DEFINE(CURL_DISABLE_COOKIES, 1, [to disable cookies support])
       AC_SUBST(CURL_DISABLE_COOKIES)
       ;;
  *)   AC_MSG_RESULT(yes)
       ;;
  esac ],
       AC_MSG_RESULT(yes)
)

dnl ************************************************************
dnl Enable hiding of internal symbols in library to reduce its size and
dnl speed dynamic linking of applications.  This currently is only supported
dnl on gcc >= 4.0 and SunPro C.
dnl
AC_MSG_CHECKING([whether to enable hidden symbols in the library])
AC_ARG_ENABLE(hidden-symbols,
AC_HELP_STRING([--enable-hidden-symbols],[Hide internal symbols in library])
AC_HELP_STRING([--disable-hidden-symbols],[Leave all symbols with default visibility in library]),
[ case "$enableval" in
  no)
       AC_MSG_RESULT(no)
       ;;
  *)   
       AC_MSG_CHECKING([whether $CC supports it])
       if test "$GCC" = yes ; then
         if $CC --help --verbose 2>&1 | grep fvisibility= > /dev/null ; then
	   AC_MSG_RESULT(yes)
	   AC_DEFINE(CURL_HIDDEN_SYMBOLS, 1, [to enable hidden symbols])
	   AC_SUBST(CURL_HIDDEN_SYMBOLS)
	   AC_DEFINE(CURL_EXTERN_SYMBOL, [__attribute__ ((visibility ("default")))], [to make a symbol visible])
	   AC_SUBST(CURL_EXTERN_SYMBOL)
	   CFLAGS="$CFLAGS -fvisibility=hidden"
         else
            AC_MSG_RESULT(no)
          fi

       else
       	 dnl Test for SunPro cc
       	 if $CC 2>&1 | grep flags >/dev/null && $CC -flags | grep xldscope= >/dev/null ; then
           AC_MSG_RESULT(yes)
	   AC_DEFINE(CURL_HIDDEN_SYMBOLS, 1, [to enable hidden symbols])
	   AC_SUBST(CURL_HIDDEN_SYMBOLS)
	   AC_DEFINE(CURL_EXTERN_SYMBOL, [__global], [to make a symbol visible])
	   AC_SUBST(CURL_EXTERN_SYMBOL)
	   CFLAGS="$CFLAGS -xldscope=hidden"
         else
           AC_MSG_RESULT(no)
         fi
       fi
       ;;
  esac ],
       AC_MSG_RESULT(no)
)

dnl ************************************************************
if test "x$ws2" = "xyes"; then

  dnl If ws2_32 is wanted, make sure it is the _last_ lib in LIBS (makes
  dnl things work when built with c-ares). But we can't just move it last
  dnl since then other stuff (SSL) won't build. So we simply append it to the
  dnl end.

  LIBS="$LIBS -lws2_32"
  TEST_SERVER_LIBS="$TEST_SERVER_LIBS -lws2_32"

fi

dnl
dnl All the library dependencies put into $LIB apply to libcurl only.
dnl Those in $CURL_LIBS apply to the curl command-line client only.
dnl Those in $TEST_SERVER_LIBS apply to test servers only.
dnl Those in $ALL_LIBS apply to all targets, including test targets.
dnl
LIBCURL_LIBS=$LIBS

AC_SUBST(LIBCURL_LIBS)
AC_SUBST(CURL_LIBS)
AC_SUBST(TEST_SERVER_LIBS)
LIBS=$ALL_LIBS  dnl LIBS is a magic variable that's used for every link

AM_CONDITIONAL(CROSSCOMPILING, test x$cross_compiling = xyes)

AC_CONFIG_FILES([Makefile \
	   docs/Makefile \
           docs/examples/Makefile \
           docs/libcurl/Makefile \
	   include/Makefile \
	   include/curl/Makefile \
	   src/Makefile \
           lib/Makefile \
           tests/Makefile \
           tests/data/Makefile \
           tests/server/Makefile \
           tests/libtest/Makefile \
	   packages/Makefile \
	   packages/Win32/Makefile \
	   packages/Win32/cygwin/Makefile \
	   packages/Linux/Makefile \
	   packages/Linux/RPM/Makefile \
	   packages/Linux/RPM/curl.spec \
	   packages/Linux/RPM/curl-ssl.spec \
           packages/Solaris/Makefile \
           packages/DOS/Makefile \
           packages/EPM/curl.list \
           packages/EPM/Makefile \
           packages/vms/Makefile \
           packages/AIX/Makefile \
           packages/AIX/RPM/Makefile \
           packages/AIX/RPM/curl.spec \
           curl-config \
           libcurl.pc
])
AC_OUTPUT

AC_MSG_NOTICE([Configured to build curl/libcurl:

  curl version:    ${VERSION}
  Host setup:      ${host}
  Install prefix:  ${prefix}
  Compiler:        ${CC}
  SSL support:     ${curl_ssl_msg}
  SSH support:     ${curl_ssh_msg}
  zlib support:    ${curl_zlib_msg}
  krb4 support:    ${curl_krb4_msg}
  GSSAPI support:  ${curl_gss_msg}
  SPNEGO support:  ${curl_spnego_msg}
  c-ares support:  ${curl_ares_msg}
  ipv6 support:    ${curl_ipv6_msg}
  IDN support:     ${curl_idn_msg}
  Build libcurl:   Shared=${enable_shared}, Static=${enable_static} 
  Built-in manual: ${curl_manual_msg}
  Verbose errors:  ${curl_verbose_msg}
  SSPI support:    ${curl_sspi_msg}
  ca cert path:    ${ca}
])