--- a/lib/ChangeLog
+++ b/lib/ChangeLog
@@ -1,3 +1,11 @@
+2004-12-19  Paul Eggert  <eggert@cs.ucla.edu>
+
+	* alloca_.h: Conditionalize on _GNULIB_ALLOCA_H, not _ALLOCA_H.
+	Remove now-obsolete comment about AIX.
+	* getdate.y: Include <alloca.h> only if HAVE_ALLOCA.
+	(YYSTACK_USE_ALLOCA): Define to 0 if !HAVE_ALLOCA.
+	(YYMAXDEPTH): New macro.
+
 2004-12-18  Bruno Haible  <bruno@clisp.org>
 
 	* fatal-signal.c (fatal_signals): Make non-const.

--- a/lib/alloca_.h
+++ b/lib/alloca_.h
@@ -18,12 +18,10 @@
    Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
    USA.  */
 
-/* When this file is included, it may be preceded only by preprocessor
-   declarations.  Thanks to AIX.  Therefore we include it right after
-   "config.h", not later.  */
-
-#ifndef _ALLOCA_H
-# define _ALLOCA_H
+/* Avoid using the symbol _ALLOCA_H here, as Bison assumes _ALLOCA_H
+   means there is a real alloca function.  */
+#ifndef _GNULIB_ALLOCA_H
+# define _GNULIB_ALLOCA_H
 
 /* alloca (N) returns a pointer to N bytes of memory
    allocated on the stack, which will last until the function returns.
@@ -51,4 +49,4 @@
 void *alloca (size_t);
 #endif
 
-#endif /* _ALLOCA_H */
+#endif /* _GNULIB_ALLOCA_H */

--- a/lib/getdate.y
+++ b/lib/getdate.y
@@ -36,7 +36,18 @@
 
 #include "getdate.h"
 
-#include <alloca.h>
+/* Use alloca only if it is known to be builtin.  */
+#if HAVE_ALLOCA
+# include <alloca.h>
+#else
+# define YYSTACK_USE_ALLOCA 0
+#endif
+
+/* Tell Bison ow much stack space is needed.  20 should be plenty for
+   this grammar, which is not right recursive.  Beware setting it too
+   high, since that might cause problems on machines whose alloca
+   implementations have lame stack-overflow checking.  */
+#define YYMAXDEPTH 20
 
 /* 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