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3rdparty/c-ares-1.18.1/configure.ac 24.8 KB
73ef4ff3   Hu Chunming   提交三方库
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  AC_PREREQ([2.60])
  
  AC_INIT([c-ares], [1.18.1],
    [c-ares mailing list: http://lists.haxx.se/listinfo/c-ares])
  
  CARES_VERSION_INFO="7:1:5"
  dnl This flag accepts an argument of the form current[:revision[:age]]. So,
  dnl passing -version-info 3:12:1 sets current to 3, revision to 12, and age to
  dnl 1.
  dnl
  dnl If either revision or age are omitted, they default to 0. Also note that age
  dnl must be less than or equal to the current interface number.
  dnl
  dnl Here are a set of rules to help you update your library version information:
  dnl
  dnl 1.Start with version information of 0:0:0 for each libtool library.
  dnl
  dnl 2.Update the version information only immediately before a public release of
  dnl your software. More frequent updates are unnecessary, and only guarantee
  dnl that the current interface number gets larger faster.
  dnl
  dnl 3.If the library source code has changed at all since the last update, then
  dnl increment revision (c:r+1:a)
  dnl
  dnl 4.If any interfaces have been added, removed, or changed since the last
  dnl update, increment current, and set revision to 0. (c+1:r=0:a)
  dnl
  dnl 5.If any interfaces have been added since the last public release, then
  dnl increment age. (c:r:a+1)
  dnl
  dnl 6.If any interfaces have been removed since the last public release, then
  dnl set age to 0. (c:r:a=0)
  dnl
  AC_SUBST([CARES_VERSION_INFO])
  
  AC_CONFIG_SRCDIR([src/lib/ares_ipv6.h])
  AC_CONFIG_HEADERS([src/lib/ares_config.h include/ares_build.h])
  AC_CONFIG_MACRO_DIR([m4])
  AM_MAINTAINER_MODE
  m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
  
  AX_REQUIRE_DEFINED([AX_CXX_COMPILE_STDCXX_11])
  
  CARES_CHECK_OPTION_DEBUG
  CARES_CHECK_OPTION_OPTIMIZE
  CARES_CHECK_OPTION_WARNINGS
  CARES_CHECK_OPTION_WERROR
  CARES_CHECK_OPTION_SYMBOL_HIDING
  CARES_CHECK_OPTION_EXPOSE_STATICS
  
  XC_CHECK_PATH_SEPARATOR
  
  dnl SED is mandatory for configure process and libtool.
  dnl Set it now, allowing it to be changed later.
  AC_PATH_PROG([SED], [sed], [not_found],
    [$PATH:/usr/bin:/usr/local/bin])
  if test -z "$SED" || test "$SED" = "not_found"; then
    AC_MSG_ERROR([sed not found in PATH. Cannot continue without sed.])
  fi
  AC_SUBST([SED])
  
  dnl GREP is mandatory for configure process and libtool.
  dnl Set it now, allowing it to be changed later.
  AC_PATH_PROG([GREP], [grep], [not_found],
    [$PATH:/usr/bin:/usr/local/bin])
  if test -z "$GREP" || test "$GREP" = "not_found"; then
    AC_MSG_ERROR([grep not found in PATH. Cannot continue without grep.])
  fi
  AC_SUBST([GREP])
  
  dnl EGREP is mandatory for configure process and libtool.
  dnl Set it now, allowing it to be changed later.
  if echo a | ($GREP -E '(a|b)') >/dev/null 2>&1; then
    AC_MSG_CHECKING([for egrep])
    EGREP="$GREP -E"
    AC_MSG_RESULT([$EGREP])
  else
    AC_PATH_PROG([EGREP], [egrep], [not_found],
      [$PATH:/usr/bin:/usr/local/bin])
  fi
  if test -z "$EGREP" || test "$EGREP" = "not_found"; then
    AC_MSG_ERROR([egrep not found in PATH. Cannot continue without egrep.])
  fi
  AC_SUBST([EGREP])
  
  dnl AR is mandatory for configure process and libtool.
  dnl This is target dependent, so check it as a tool.
  if test -z "$AR"; then
    dnl allow it to be overridden
    AC_PATH_TOOL([AR], [ar], [not_found],
      [$PATH:/usr/bin:/usr/local/bin])
    if test -z "$AR" || test "$AR" = "not_found"; then
      AC_MSG_ERROR([ar not found in PATH. Cannot continue without ar.])
    fi
  fi
  AC_SUBST([AR])
  
  AX_CODE_COVERAGE
  
  
  dnl
  dnl Detect the canonical host and target build environment
  dnl
  
  AC_CANONICAL_HOST
  dnl Get system canonical name
  AC_DEFINE_UNQUOTED(OS, "${host}", [cpu-machine-OS])
  
  XC_CHECK_PROG_CC
  AX_CXX_COMPILE_STDCXX_11([noext],[optional])
  
  XC_AUTOMAKE
  
  dnl This defines _ALL_SOURCE for AIX
  CARES_CHECK_AIX_ALL_SOURCE
  
  dnl Our configure and build reentrant settings
  CARES_CONFIGURE_THREAD_SAFE
  CARES_CONFIGURE_REENTRANT
  
  dnl check for how to do large files
  AC_SYS_LARGEFILE
  
  case $host_os in
    solaris*)
      AC_DEFINE(ETC_INET, 1, [if a /etc/inet dir is being used])
      ;;
  esac
  
  XC_LIBTOOL
  
  
  #
  # Automake conditionals based on libtool related checks
  #
  
  AM_CONDITIONAL([CARES_LT_SHLIB_USE_VERSION_INFO],
    [test "x$xc_lt_shlib_use_version_info" = 'xyes'])
  AM_CONDITIONAL([CARES_LT_SHLIB_USE_NO_UNDEFINED],
    [test "x$xc_lt_shlib_use_no_undefined" = 'xyes'])
  AM_CONDITIONAL([CARES_LT_SHLIB_USE_MIMPURE_TEXT],
    [test "x$xc_lt_shlib_use_mimpure_text" = 'xyes'])
  
  #
  # Due to libtool and automake machinery limitations of not allowing
  # specifying separate CPPFLAGS or CFLAGS when compiling objects for
  # inclusion of these in shared or static libraries, we are forced to
  # build using separate configure runs for shared and static libraries
  # on systems where different CPPFLAGS or CFLAGS are mandatory in order
  # to compile objects for each kind of library. Notice that relying on
  # the '-DPIC' CFLAG that libtool provides is not valid given that the
  # user might for example choose to build static libraries with PIC.
  #
  
  #
  # Make our Makefile.am files use the staticlib CPPFLAG only when strictly
  # targeting a static library and not building its shared counterpart.
  #
  
  AM_CONDITIONAL([USE_CPPFLAG_CARES_STATICLIB],
    [test "x$xc_lt_build_static_only" = 'xyes'])
  
  #
  # Make staticlib CPPFLAG variable and its definition visible in output
  # files unconditionally, providing an empty definition unless strictly
  # targeting a static library and not building its shared counterpart.
  #
  
  CPPFLAG_CARES_STATICLIB=
  if test "x$xc_lt_build_static_only" = 'xyes'; then
    CPPFLAG_CARES_STATICLIB='-DCARES_STATICLIB'
  fi
  AC_SUBST([CPPFLAG_CARES_STATICLIB])
  
  dnl **********************************************************************
  dnl platform/compiler/architecture specific checks/flags
  dnl **********************************************************************
  
  CARES_CHECK_COMPILER
  CARES_SET_COMPILER_BASIC_OPTS
  CARES_SET_COMPILER_DEBUG_OPTS
  CARES_SET_COMPILER_OPTIMIZE_OPTS
  CARES_SET_COMPILER_WARNING_OPTS
  
  if test "$compiler_id" = "INTEL_UNIX_C"; then
    #
    if test "$compiler_num" -ge "1000"; then
      dnl icc 10.X or later
      CFLAGS="$CFLAGS -shared-intel"
    elif test "$compiler_num" -ge "900"; then
      dnl icc 9.X specific
      CFLAGS="$CFLAGS -i-dynamic"
    fi
    #
  fi
  
  CARES_CHECK_COMPILER_HALT_ON_ERROR
  CARES_CHECK_COMPILER_ARRAY_SIZE_NEGATIVE
  CARES_CHECK_COMPILER_PROTOTYPE_MISMATCH
  CARES_CHECK_COMPILER_SYMBOL_HIDING
  
  dnl **********************************************************************
  dnl Compilation based checks should not be done before this point.
  dnl **********************************************************************
  
  dnl **********************************************************************
  dnl Make sure that our checks for headers windows.h winsock.h winsock2.h
  dnl and ws2tcpip.h take precedence over any other further checks which
  dnl could be done later using AC_CHECK_HEADER or AC_CHECK_HEADERS for
  dnl this specific header files. And do them before its results are used.
  dnl **********************************************************************
  
  CURL_CHECK_HEADER_WINDOWS
  CURL_CHECK_NATIVE_WINDOWS
  case X-"$ac_cv_native_windows" in
    X-yes)
      CURL_CHECK_HEADER_WINSOCK
      CURL_CHECK_HEADER_WINSOCK2
      CURL_CHECK_HEADER_WS2TCPIP
      CPPFLAGS="$CPPFLAGS -D_WIN32_WINNT=0x0600"
      ;;
    *)
      ac_cv_header_winsock_h="no"
      ac_cv_header_winsock2_h="no"
      ac_cv_header_ws2tcpip_h="no"
      ;;
  esac
  
  dnl **********************************************************************
  dnl Checks for libraries.
  dnl **********************************************************************
  
  CARES_CHECK_LIB_XNET
  
  dnl gethostbyname without lib or in the nsl lib?
  AC_CHECK_FUNC(gethostbyname,
                [HAVE_GETHOSTBYNAME="1"
                ],
                [ AC_CHECK_LIB(nsl, gethostbyname,
                               [HAVE_GETHOSTBYNAME="1"
                               LIBS="$LIBS -lnsl"
                               ])
                ])
  
  if test "$HAVE_GETHOSTBYNAME" != "1"
  then
    dnl gethostbyname in the socket lib?
    AC_CHECK_LIB(socket, gethostbyname,
                 [HAVE_GETHOSTBYNAME="1"
                 LIBS="$LIBS -lsocket"
                 ])
  fi
  
  dnl At least one system has been identified to require BOTH nsl and socket
  dnl libs at the same time to link properly.
  if test "$HAVE_GETHOSTBYNAME" != "1"
  then
    AC_MSG_CHECKING([for gethostbyname with both nsl and socket libs])
    my_ac_save_LIBS=$LIBS
    LIBS="-lnsl -lsocket $LIBS"
    AC_LINK_IFELSE([
      AC_LANG_PROGRAM([[
      ]],[[
        gethostbyname();
      ]])
    ],[
      AC_MSG_RESULT([yes])
      HAVE_GETHOSTBYNAME="1"
    ],[
      AC_MSG_RESULT([no])
      LIBS=$my_ac_save_LIBS
    ])
  fi
  
  if test "$HAVE_GETHOSTBYNAME" != "1"
  then
    dnl This is for winsock systems
    if test "$ac_cv_header_windows_h" = "yes"; then
      if test "$ac_cv_header_winsock_h" = "yes"; then
        case $host in
          *-*-mingw32ce*)
            winsock_LIB="-lwinsock"
            ;;
          *)
            winsock_LIB="-lwsock32"
            ;;
        esac
      fi
      if test "$ac_cv_header_winsock2_h" = "yes"; then
        winsock_LIB="-lws2_32"
      fi
      if test ! -z "$winsock_LIB"; then
        my_ac_save_LIBS=$LIBS
        LIBS="$winsock_LIB $LIBS"
        AC_MSG_CHECKING([for gethostbyname in $winsock_LIB])
        AC_LINK_IFELSE([
          AC_LANG_PROGRAM([[
  #ifdef HAVE_WINDOWS_H
  #ifndef WIN32_LEAN_AND_MEAN
  #define WIN32_LEAN_AND_MEAN
  #endif
  #include <windows.h>
  #ifdef HAVE_WINSOCK2_H
  #include <winsock2.h>
  #else
  #ifdef HAVE_WINSOCK_H
  #include <winsock.h>
  #endif
  #endif
  #endif
          ]],[[
            gethostbyname("www.dummysite.com");
          ]])
        ],[
          AC_MSG_RESULT([yes])
          HAVE_GETHOSTBYNAME="1"
        ],[
          AC_MSG_RESULT([no])
          winsock_LIB=""
          LIBS=$my_ac_save_LIBS
        ])
      fi
    fi
  fi
  
  if test "$HAVE_GETHOSTBYNAME" != "1"
  then
    dnl This is for Minix 3.1
    AC_MSG_CHECKING([for gethostbyname for Minix 3])
    AC_LINK_IFELSE([
      AC_LANG_PROGRAM([[
  /* Older Minix versions may need <net/gen/netdb.h> here instead */
  #include <netdb.h>
      ]],[[
        gethostbyname("www.dummysite.com");
      ]])
    ],[
      AC_MSG_RESULT([yes])
      HAVE_GETHOSTBYNAME="1"
    ],[
      AC_MSG_RESULT([no])
    ])
  fi
  
  if test "$HAVE_GETHOSTBYNAME" != "1"
  then
    dnl This is for eCos with a stubbed DNS implementation
    AC_MSG_CHECKING([for gethostbyname for eCos])
    AC_LINK_IFELSE([
      AC_LANG_PROGRAM([[
  #include <stdio.h>
  #include <netdb.h>
      ]],[[
        gethostbyname("www.dummysite.com");
      ]])
    ],[
      AC_MSG_RESULT([yes])
      HAVE_GETHOSTBYNAME="1"
    ],[
      AC_MSG_RESULT([no])
    ])
  fi
  
  if test "$HAVE_GETHOSTBYNAME" != "1"
  then
    dnl gethostbyname in the net lib - for BeOS
    AC_CHECK_LIB(net, gethostbyname,
                 [HAVE_GETHOSTBYNAME="1"
                 LIBS="$LIBS -lnet"
                 ])
  fi
  
  
  if test "$HAVE_GETHOSTBYNAME" != "1"; then
    AC_MSG_ERROR([couldn't find libraries for gethostbyname()])
  fi
  
  dnl resolv lib for Apple (MacOS and iOS)
  AS_IF([test "x$host_vendor" = "xapple"], [
    AC_SEARCH_LIBS([res_servicename], [resolv], [
      AC_DEFINE([CARES_USE_LIBRESOLV], [1], [Use resolver library to configure cares])
    ], [
      AC_MSG_ERROR([Unable to find libresolv which is required for iPhone targets])
    ])
  ])
  
  dnl resolv lib for z/OS
  AS_IF([test "x$host_vendor" = "xibm" -a "x$host_os" = "xopenedition" ], [
    AC_SEARCH_LIBS([res_init], [resolv], [
      AC_DEFINE([CARES_USE_LIBRESOLV], [1], [Use resolver library to configure cares])
    ], [
      AC_MSG_ERROR([Unable to find libresolv which is required for z/OS])
    ])
  ])
  
  dnl resolve lib?
  AC_CHECK_FUNC(strcasecmp, , [ AC_CHECK_LIB(resolve, strcasecmp) ])
  
  if test "$ac_cv_lib_resolve_strcasecmp" = "$ac_cv_func_strcasecmp"; then
    AC_CHECK_LIB(resolve, strcasecmp,
                [LIBS="-lresolve $LIBS"],
                 ,
                 -lnsl)
  fi
  ac_cv_func_strcasecmp="no"
  
  dnl Windows builds require linking to iphlpapi
  if test "$ac_cv_header_winsock2_h" = "yes"; then
    LIBS="$LIBS -liphlpapi"
  fi
  
  CARES_CHECK_LIBS_CONNECT
  
  dnl iOS 10?
  AS_IF([test "x$host_vendor" = "xapple"], [
    AC_MSG_CHECKING([for iOS minimum version 10 or later])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
  #include <stdio.h>
  #include <TargetConditionals.h>
      ]], [[
  #if TARGET_OS_IPHONE == 0 || __IPHONE_OS_VERSION_MIN_REQUIRED < 100000
  #error Not iOS 10 or later
  #endif
  return 0;
     ]])
    ],[
      AC_MSG_RESULT([yes])
      ac_cv_ios_10="yes"
    ],[
      AC_MSG_RESULT([no])
    ])
  ])
  
  dnl macOS 10.12?
  AS_IF([test "x$host_vendor" = "xapple"], [
    AC_MSG_CHECKING([for macOS minimum version 10.12 or later])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
  #include <stdio.h>
  #include <TargetConditionals.h>
      ]], [[
  #ifndef MAC_OS_X_VERSION_10_12
  #  define MAC_OS_X_VERSION_10_12 101200
  #endif
  #if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_12
  #error Not macOS 10.12 or later
  #endif
  return 0;
     ]])
    ],[
      AC_MSG_RESULT([yes])
      ac_cv_macos_10_12="yes"
    ],[
      AC_MSG_RESULT([no])
    ])
  ])
  
  dnl **********************************************************************
  dnl In case that function clock_gettime with monotonic timer is available,
  dnl check for additional required libraries.
  dnl **********************************************************************
  dnl Xcode 8 bug: iOS when targeting less than 10, or macOS when targeting less than 10.12 will
  dnl say clock_gettime exists, it is a weak symbol that only exists in iOS 10 or macOS 10.12 and will
  dnl cause a crash at runtime when running on older versions.  Skip finding CLOCK_MONOTONIC on older
  dnl Apple OS's.
  if test "x$host_vendor" != "xapple" || test "x$ac_cv_ios_10" = "xyes" || test "x$ac_cv_macos_10_12" = "xyes"; then
    CURL_CHECK_LIBS_CLOCK_GETTIME_MONOTONIC
  fi
  
  AC_MSG_CHECKING([whether to use libgcc])
  AC_ARG_ENABLE(libgcc,
  AS_HELP_STRING([--enable-libgcc],[use libgcc when linking]),
  [ case "$enableval" in
    yes)
          LIBS="$LIBS -lgcc"
         AC_MSG_RESULT(yes)
         ;;
    *)   AC_MSG_RESULT(no)
         ;;
    esac ],
         AC_MSG_RESULT(no)
  )
  
  
  dnl Let's hope this split URL remains working:
  dnl http://publibn.boulder.ibm.com/doc_link/en_US/a_doc_lib/aixprggd/ \
  dnl genprogc/thread_quick_ref.htm
  
  
  dnl **********************************************************************
  dnl Back to "normal" configuring
  dnl **********************************************************************
  
  dnl Checks for header files.
  STDC_HEADERS
  
  AC_PROG_EGREP
  
  
  CURL_CHECK_HEADER_MALLOC
  CURL_CHECK_HEADER_MEMORY
  
  dnl check for a few basic system headers we need
  AC_CHECK_HEADERS(
         sys/types.h \
         sys/time.h \
         sys/select.h \
         sys/socket.h \
         sys/ioctl.h \
         sys/param.h \
         sys/uio.h \
         assert.h \
         netdb.h \
         netinet/in.h \
         netinet/tcp.h \
         net/if.h \
         errno.h \
         socket.h \
         strings.h \
         stdbool.h \
         time.h \
         limits.h \
         arpa/nameser.h \
         arpa/nameser_compat.h \
         arpa/inet.h,
  dnl to do if not found
  [],
  dnl to do if found
  [],
  dnl default includes
  [
  #ifdef HAVE_SYS_TYPES_H
  #include <sys/types.h>
  #endif
  #ifdef HAVE_SYS_TIME_H
  #include <sys/time.h>
  #endif
  dnl We do this default-include simply to make sure that the nameser_compat.h
  dnl header *REALLY* can be include after the new nameser.h. It seems AIX 5.1
  dnl (and others?) is not designed to allow this.
  #ifdef HAVE_ARPA_NAMESER_H
  #include <arpa/nameser.h>
  #endif
  
  dnl *Sigh* these are needed in order for net/if.h to get properly detected.
  #ifdef HAVE_SYS_SOCKET_H
  #include <sys/socket.h>
  #endif
  #ifdef HAVE_NETINET_IN_H
  #include <netinet/in.h>
  #endif
  ]
  )
  
  dnl Test and set CARES_HAVE_ARPA_NAMESER_H / CARES_HAVE_ARPA_NAMESER_COMPAT_H
  AC_CHECK_DECL([HAVE_ARPA_NAMESER_H],
  [
  CARES_DEFINE_UNQUOTED([CARES_HAVE_ARPA_NAMESER_H])
  ],
  []
  )
  AC_CHECK_DECL([HAVE_ARPA_NAMESER_COMPAT_H],
  [
  CARES_DEFINE_UNQUOTED([CARES_HAVE_ARPA_NAMESER_COMPAT_H])
  ],
  []
  )
  
  dnl Checks for typedefs, structures, and compiler characteristics.
  AC_C_CONST
  AC_TYPE_SIZE_T
  m4_warn([obsolete],
  [Update your code to rely only on HAVE_SYS_TIME_H,
  then remove this warning and the obsolete code below it.
  All current systems provide time.h; it need not be checked for.
  Not all systems provide sys/time.h, but those that do, all allow
  you to include it and time.h simultaneously.])dnl
  AC_CHECK_HEADERS_ONCE([sys/time.h])
  # Obsolete code to be removed.
  if test $ac_cv_header_sys_time_h = yes; then
    AC_DEFINE([TIME_WITH_SYS_TIME],[1],[Define to 1 if you can safely include both <sys/time.h>
  	     and <time.h>.  This macro is obsolete.])
  fi
  # End of obsolete code.
  
  CURL_CHECK_STRUCT_TIMEVAL
  
  AC_CHECK_TYPE(long long,
     [AC_DEFINE(HAVE_LONGLONG, 1,
       [Define to 1 if the compiler supports the 'long long' data type.])]
     longlong="yes"
  )
  
  if test "xyes" = "x$longlong"; then
    AC_MSG_CHECKING([if numberLL works])
    AC_COMPILE_IFELSE([
      AC_LANG_PROGRAM([[
      ]],[[
        long long val = 1000LL;
      ]])
    ],[
      AC_MSG_RESULT([yes])
      AC_DEFINE(HAVE_LL, 1, [if your compiler supports LL])
    ],[
      AC_MSG_RESULT([no])
    ])
  fi
  
  
  # check for ssize_t
  AC_CHECK_TYPE(ssize_t, [ CARES_TYPEOF_ARES_SSIZE_T=ssize_t ],
    [ CARES_TYPEOF_ARES_SSIZE_T=int ])
  
  AC_DEFINE_UNQUOTED([CARES_TYPEOF_ARES_SSIZE_T], ${CARES_TYPEOF_ARES_SSIZE_T},
    [the signed version of size_t])
  
  
  # check for bool type
  AC_CHECK_TYPE([bool],[
    AC_DEFINE(HAVE_BOOL_T, 1,
      [Define to 1 if bool is an available type.])
  ], ,[
  #ifdef HAVE_SYS_TYPES_H
  #include <sys/types.h>
  #endif
  #ifdef HAVE_STDBOOL_H
  #include <stdbool.h>
  #endif
  ])
  
  CARES_CONFIGURE_ARES_SOCKLEN_T
  
  TYPE_IN_ADDR_T
  
  TYPE_SOCKADDR_STORAGE
  
  TYPE_SIG_ATOMIC_T
  
  m4_warn([obsolete],
  [your code may safely assume C89 semantics that RETSIGTYPE is void.
  Remove this warning and the `AC_CACHE_CHECK' when you adjust the code.])dnl
  AC_CACHE_CHECK([return type of signal handlers],[ac_cv_type_signal],[AC_COMPILE_IFELSE(
  [AC_LANG_PROGRAM([#include <sys/types.h>
  #include <signal.h>
  ],
  		 [return *(signal (0, 0)) (0) == 1;])],
  		   [ac_cv_type_signal=int],
  		   [ac_cv_type_signal=void])])
  AC_DEFINE_UNQUOTED([RETSIGTYPE],[$ac_cv_type_signal],[Define as the return type of signal handlers
  		    (`int' or `void').])
  
  
  CURL_CHECK_FUNC_RECV
  CURL_CHECK_FUNC_RECVFROM
  CURL_CHECK_FUNC_SEND
  CURL_CHECK_MSG_NOSIGNAL
  
  CARES_CHECK_FUNC_CLOSESOCKET
  CARES_CHECK_FUNC_CLOSESOCKET_CAMEL
  CARES_CHECK_FUNC_CONNECT
  CARES_CHECK_FUNC_FCNTL
  CARES_CHECK_FUNC_FREEADDRINFO
  CARES_CHECK_FUNC_GETADDRINFO
  CARES_CHECK_FUNC_GETENV
  CARES_CHECK_FUNC_GETHOSTBYADDR
  CARES_CHECK_FUNC_GETHOSTBYNAME
  CARES_CHECK_FUNC_GETHOSTNAME
  CARES_CHECK_FUNC_GETSERVBYPORT_R
  CARES_CHECK_FUNC_INET_NET_PTON
  CARES_CHECK_FUNC_INET_NTOP
  CARES_CHECK_FUNC_INET_PTON
  CARES_CHECK_FUNC_IOCTL
  CARES_CHECK_FUNC_IOCTLSOCKET
  CARES_CHECK_FUNC_IOCTLSOCKET_CAMEL
  CARES_CHECK_FUNC_SETSOCKOPT
  CARES_CHECK_FUNC_SOCKET
  CARES_CHECK_FUNC_STRCASECMP
  CARES_CHECK_FUNC_STRCMPI
  CARES_CHECK_FUNC_STRDUP
  CARES_CHECK_FUNC_STRICMP
  CARES_CHECK_FUNC_STRNCASECMP
  CARES_CHECK_FUNC_STRNCMPI
  CARES_CHECK_FUNC_STRNICMP
  CARES_CHECK_FUNC_WRITEV
  
  
  dnl check for AF_INET6
  CARES_CHECK_CONSTANT(
    [
  #undef inline
  #ifdef HAVE_WINDOWS_H
  #ifndef WIN32_LEAN_AND_MEAN
  #define WIN32_LEAN_AND_MEAN
  #endif
  #include <windows.h>
  #ifdef HAVE_WINSOCK2_H
  #include <winsock2.h>
  #endif
  #else
  #ifdef HAVE_SYS_TYPES_H
  #include <sys/types.h>
  #endif
  #ifdef HAVE_SYS_SOCKET_H
  #include <sys/socket.h>
  #endif
  #endif
    ], [PF_INET6],
       AC_DEFINE_UNQUOTED(HAVE_PF_INET6,1,[Define to 1 if you have PF_INET6.])
  )
  
  dnl check for PF_INET6
  CARES_CHECK_CONSTANT(
    [
  #undef inline
  #ifdef HAVE_WINDOWS_H
  #ifndef WIN32_LEAN_AND_MEAN
  #define WIN32_LEAN_AND_MEAN
  #endif
  #include <windows.h>
  #ifdef HAVE_WINSOCK2_H
  #include <winsock2.h>
  #endif
  #else
  #ifdef HAVE_SYS_TYPES_H
  #include <sys/types.h>
  #endif
  #ifdef HAVE_SYS_SOCKET_H
  #include <sys/socket.h>
  #endif
  #endif
    ], [AF_INET6],
       AC_DEFINE_UNQUOTED(HAVE_AF_INET6,1,[Define to 1 if you have AF_INET6.])
  )
  
  
  dnl check for the in6_addr structure
  CARES_CHECK_STRUCT(
    [
  #undef inline
  #ifdef HAVE_WINDOWS_H
  #ifndef WIN32_LEAN_AND_MEAN
  #define WIN32_LEAN_AND_MEAN
  #endif
  #include <windows.h>
  #ifdef HAVE_WINSOCK2_H
  #include <winsock2.h>
  #ifdef HAVE_WS2TCPIP_H
  #include <ws2tcpip.h>
  #endif
  #endif
  #else
  #ifdef HAVE_SYS_TYPES_H
  #include <sys/types.h>
  #endif
  #ifdef HAVE_NETINET_IN_H
  #include <netinet/in.h>
  #endif
  #endif
    ], [in6_addr],
       AC_DEFINE_UNQUOTED(HAVE_STRUCT_IN6_ADDR,1,[Define to 1 if you have struct in6_addr.])
  )
  
  dnl check for the sockaddr_in6 structure
  CARES_CHECK_STRUCT(
    [
  #undef inline
  #ifdef HAVE_WINDOWS_H
  #ifndef WIN32_LEAN_AND_MEAN
  #define WIN32_LEAN_AND_MEAN
  #endif
  #include <windows.h>
  #ifdef HAVE_WINSOCK2_H
  #include <winsock2.h>
  #ifdef HAVE_WS2TCPIP_H
  #include <ws2tcpip.h>
  #endif
  #endif
  #else
  #ifdef HAVE_SYS_TYPES_H
  #include <sys/types.h>
  #endif
  #ifdef HAVE_NETINET_IN_H
  #include <netinet/in.h>
  #endif
  #endif
    ], [sockaddr_in6],
       AC_DEFINE_UNQUOTED(HAVE_STRUCT_SOCKADDR_IN6,1,
         [Define to 1 if you have struct sockaddr_in6.]) ac_have_sockaddr_in6=yes
  )
  
  AC_CHECK_MEMBER(struct sockaddr_in6.sin6_scope_id,
      AC_DEFINE_UNQUOTED(HAVE_SOCKADDR_IN6_SIN6_SCOPE_ID,1,
        [Define to 1 if your struct sockaddr_in6 has sin6_scope_id.])
     , ,
    [
  #undef inline
  #ifdef HAVE_WINDOWS_H
  #ifndef WIN32_LEAN_AND_MEAN
  #define WIN32_LEAN_AND_MEAN
  #endif
  #include <windows.h>
  #ifdef HAVE_WINSOCK2_H
  #include <winsock2.h>
  #ifdef HAVE_WS2TCPIP_H
  #include <ws2tcpip.h>
  #endif
  #endif
  #else
  #ifdef HAVE_SYS_TYPES_H
  #include <sys/types.h>
  #endif
  #ifdef HAVE_NETINET_IN_H
  #include <netinet/in.h>
  #endif
  #endif
    ])
  
  dnl check for the addrinfo structure
  AC_CHECK_MEMBER(struct addrinfo.ai_flags,
       AC_DEFINE_UNQUOTED(HAVE_STRUCT_ADDRINFO,1,
         [Define to 1 if you have struct addrinfo.]),,
    [
  #undef inline
  #ifdef HAVE_WINDOWS_H
  #ifndef WIN32_LEAN_AND_MEAN
  #define WIN32_LEAN_AND_MEAN
  #endif
  #include <windows.h>
  #ifdef HAVE_WINSOCK2_H
  #include <winsock2.h>
  #ifdef HAVE_WS2TCPIP_H
  #include <ws2tcpip.h>
  #endif
  #endif
  #else
  #ifdef HAVE_SYS_TYPES_H
  #include <sys/types.h>
  #endif
  #ifdef HAVE_NETINET_IN_H
  #include <netinet/in.h>
  #endif
  #ifdef HAVE_SYS_SOCKET_H
  #include <sys/socket.h>
  #endif
  #ifdef HAVE_NETDB_H
  #include <netdb.h>
  #endif
  #endif
    ]
  )
  
  
  AC_CHECK_FUNCS([bitncmp \
    gettimeofday \
    if_indextoname
  ],[
  ],[
    func="$ac_func"
    AC_MSG_CHECKING([deeper for $func])
    AC_LINK_IFELSE([
      AC_LANG_PROGRAM([[
      ]],[[
        $func ();
      ]])
    ],[
      AC_MSG_RESULT([yes])
      eval "ac_cv_func_$func=yes"
      AC_DEFINE_UNQUOTED(XC_SH_TR_CPP([HAVE_$func]), [1],
        [Define to 1 if you have the $func function.])
    ],[
      AC_MSG_RESULT([but still no])
    ])
  ])
  
  dnl Android. Some variants like arm64 may no longer have __system_property_get
  dnl in libc, but they are defined in the headers.  Perform a link check.
  AC_CHECK_FUNC([__system_property_get], [
      AC_DEFINE([HAVE___SYSTEM_PROPERTY_GET], [1], [Define if __system_property_get exists.])
  ])
  
  dnl Check if the getnameinfo function is available
  dnl and get the types of five of its arguments.
  CURL_CHECK_FUNC_GETNAMEINFO
  
  
  AC_C_BIGENDIAN(
      [AC_DEFINE(ARES_BIG_ENDIAN, 1,
        [define this if ares is built for a big endian system])],
      ,
      [AC_MSG_WARN([couldn't figure out endianess, assuming little endian!])]
  )
  
  dnl Check for user-specified random device
  AC_ARG_WITH(random,
  AS_HELP_STRING([--with-random=FILE],
                 [read randomness from FILE (default=/dev/urandom)]),
      [ CARES_RANDOM_FILE="$withval" ],
      [
          dnl Check for random device.  If we're cross compiling, we can't
          dnl check, and it's better to assume it doesn't exist than it is
          dnl to fail on AC_CHECK_FILE or later.
          if test "$cross_compiling" = "no"; then
            AC_CHECK_FILE("/dev/urandom", [ CARES_RANDOM_FILE="/dev/urandom"] )
          else
            AC_MSG_WARN([cannot check for /dev/urandom while cross compiling; assuming none])
          fi
  
      ]
  )
  if test -n "$CARES_RANDOM_FILE" && test X"$CARES_RANDOM_FILE" != Xno ; then
          AC_SUBST(CARES_RANDOM_FILE)
          AC_DEFINE_UNQUOTED(CARES_RANDOM_FILE, "$CARES_RANDOM_FILE",
          [a suitable file/device to read random data from])
  fi
  
  CARES_CHECK_OPTION_NONBLOCKING
  CARES_CHECK_NONBLOCKING_SOCKET
  
  CARES_CONFIGURE_SYMBOL_HIDING
  
  CARES_PRIVATE_LIBS="$LIBS"
  AC_SUBST(CARES_PRIVATE_LIBS)
  
  CARES_CFLAG_EXTRAS=""
  if test X"$want_werror" = Xyes; then
    CARES_CFLAG_EXTRAS="-Werror"
  fi
  AC_SUBST(CARES_CFLAG_EXTRAS)
  
  dnl squeeze whitespace out of some variables
  
  squeeze CFLAGS
  squeeze CPPFLAGS
  squeeze DEFS
  squeeze LDFLAGS
  squeeze LIBS
  
  squeeze CARES_PRIVATE_LIBS
  
  XC_CHECK_BUILD_FLAGS
  
  AC_MSG_CHECKING([whether to build tests])
  AC_ARG_ENABLE(tests,
  	AS_HELP_STRING([--enable-tests], [build test suite]),
  	[ build_tests="$enableval" ],
  	[ if test "x$HAVE_CXX11" = "x1" && test "x$cross_compiling" = "xno" ; then
  	    build_tests="yes"
  	  else
  	    build_tests="no"
  	  fi
  	]
  )
  
  if test "x$build_tests" = "xyes" ; then
  	if test "x$HAVE_CXX11" = "0" ; then
  		AC_MSG_ERROR([*** Building tests requires a CXX11 compiler])
  	fi
  	if test "x$cross_compiling" = "xyes" ; then
  		AC_MSG_ERROR([*** Tests not supported when cross compiling])
  	fi
  fi
  AC_MSG_RESULT([$build_tests])
  
  
  BUILD_SUBDIRS="include src docs"
  if test "x$build_tests" = "xyes" ; then
    AC_CONFIG_SUBDIRS([test])
    BUILD_SUBDIRS="${BUILD_SUBDIRS} test"
  fi
  
  AC_SUBST(BUILD_SUBDIRS)
  
  AC_CONFIG_FILES([Makefile           \
                   include/Makefile   \
                   src/Makefile       \
                   src/lib/Makefile   \
                   src/tools/Makefile \
                   docs/Makefile      \
                   libcares.pc ])
  
  AC_OUTPUT
  XC_AMEND_DISTCLEAN(['.'])