acinclude.m4

        { return arg1 + arg2 + arg3; }
        int fun2(int arg1, int arg2)
        { return arg1 + arg2; }
      ],[
        int res3 = gcc_vmacro3(1, 2, 3);
        int res2 = gcc_vmacro2(1, 2);
      ])
    ],[
      curl_cv_variadic_macros_gcc="yes"
    ],[
      curl_cv_variadic_macros_gcc="no"
    ])
  ])
  case "$curl_cv_variadic_macros_gcc" in
    yes)
      AC_DEFINE_UNQUOTED(HAVE_VARIADIC_MACROS_GCC, 1,
        [Define to 1 if compiler supports old gcc variadic macro style.])
      ;;
  esac
])


dnl CURL_CHECK_NATIVE_WINDOWS
dnl -------------------------------------------------
dnl Check if building a native Windows target

AC_DEFUN([CURL_CHECK_NATIVE_WINDOWS], [
  AC_REQUIRE([CURL_CHECK_HEADER_WINDOWS])dnl
  AC_CACHE_CHECK([whether build target is a native Windows one], [ac_cv_native_windows], [
    if test "$ac_cv_header_windows_h" = "no"; then
      ac_cv_native_windows="no"
    else
      AC_COMPILE_IFELSE([
        AC_LANG_PROGRAM([
        ],[
#ifdef __MINGW32__
          int dummy=1;
#else
          Not a native Windows build target.
#endif
        ])
      ],[
        ac_cv_native_windows="yes"
      ],[
        ac_cv_native_windows="no"
      ])
    fi
  ])
  case "$ac_cv_native_windows" in
    yes)
      AC_DEFINE_UNQUOTED(NATIVE_WINDOWS, 1,
        [Define to 1 if you are building a native Windows target.])
      ;;
  esac
])