1 files changed, 12 insertions, 0 deletions
diff --git a/win/tcl.m4 b/win/tcl.m4
index 906e4ff..29e64fc 100644
--- a/win/tcl.m4
+++ b/win/tcl.m4
@@ -319,6 +319,15 @@ AC_DEFUN(SC_ENABLE_SYMBOLS, [
 #--------------------------------------------------------------------
 
 AC_DEFUN(SC_CONFIG_CFLAGS, [
+
+    # Step 0: Enable 64 bit support?
+    # Currently Tk requires no extra flags for 64bit support.
+    # It just needs to find the right compiler, which is up to the user.
+
+    AC_MSG_CHECKING([if 64bit support is requested])
+    AC_ARG_ENABLE(64bit,[  --enable-64bit          enable 64bit support (where applicable)], [do64bit=$enableval], [do64bit=no])
+    AC_MSG_RESULT($do64bit)
+
     AC_MSG_CHECKING([compiler flags])
 
     # Set some defaults (may get changed below)
@@ -330,6 +339,9 @@ AC_DEFUN(SC_CONFIG_CFLAGS, [
     # set various compiler flags depending on whether we are using gcc or cl
     
     if test "${GCC}" = "yes" ; then
+	if test "$do64bit" = "yes" ; then
+	    AC_MSG_WARN("64bit mode not supported with GCC on Windows")
+	fi
 	SHLIB_LD=""
 	SHLIB_LD_LIBS=""
 	LIBS=""