Hi,
I've seen this nasty warning now a couple of times also with other builds than mine;
and I believe this simple patch can avoid the warning without changing anything else:

--- getdate.y.orig 2004-05-11 13:30:23.000000000 +0200
+++ getdate.y 2004-06-21 18:52:38.000000000 +0200
@@ -26,6 +26,11 @@
 #define YYDEBUG 0
 #endif
 
+#ifndef YYSTACK_USE_ALLOCA
+ /* to satisfy gcc -Wundef, we set this to 0 */
+#define YYSTACK_USE_ALLOCA 0
+#endif
+
 /* Since the code of getdate.y is not included in the Emacs executable
    itself, there is no need to #define static in this file. Even if
    the code were included in the Emacs executable, it probably

Guenter.