--- a/lisp/cl.el	Wed Oct 27 23:36:14 2010 +0200
+++ b/lisp/cl.el	Thu Oct 28 23:53:24 2010 +0200
@@ -363,7 +363,13 @@
 
 (defalias 'first 'car)
 (defalias 'rest 'cdr)
-(defalias 'endp 'null)
+
+;; XEmacs change; this needs to error if handed a non-list.
+(defun endp (list)
+  "Return t if LIST is nil, or nil if LIST is a cons. Error otherwise."
+  (prog1
+      (null list)
+    (and list (atom list) (error 'wrong-type-argument #'listp list))))
 
 ;; XEmacs change: make it a real function
 (defun second (x)
@@ -517,24 +523,28 @@
 
 ;;; `last' is implemented as a C primitive, as of 1998-11
 
-(defun list* (arg &rest rest)   ; See compiler macro in cl-macs.el
-  "Return a new list with specified args as elements, cons'd to last arg.
-Thus, `(list* A B C D)' is equivalent to `(nconc (list A B C) D)', or to
-`(cons A (cons B (cons C D)))'."
-  (cond ((not rest) arg)
-	((not (cdr rest)) (cons arg (car rest)))
-	(t (let* ((n (length rest))
-		  (copy (copy-sequence rest))
-		  (last (nthcdr (- n 2) copy)))
-	     (setcdr last (car (cdr last)))
-	     (cons arg copy)))))
+;;; XEmacs: `list*' is in subr.el.
+
+;; XEmacs; handle dotted lists properly, error on circularity and if LIST is
+;; not a list.
+(defun ldiff (list sublist)
+  "Return a copy of LIST with the tail SUBLIST removed.
 
-(defun ldiff (list sublist)
-  "Return a copy of LIST with the tail SUBLIST removed."
-  (let ((res nil))
-    (while (and (consp list) (not (eq list sublist)))
-      (push (pop list) res))
-    (nreverse res)))
+If SUBLIST is the same Lisp object as LIST, return nil.  If SUBLIST is
+not present in the list structure of LIST (that is, it is not the cdr
+of some cons making up LIST), this function is equivalent to
+`copy-list'.  LIST may be dotted."
+  (check-argument-type #'listp list)
+  (and list (not (eq list sublist))
+       (let ((before list) (evenp t) result)
+	 (prog1
+	     (setq result (list (car list)))
+	   (while (and (setq list (cdr-safe list)) (not (eql list sublist)))
+	     (setcdr result (if (consp list) (list (car list)) list))
+	     (setq result (cdr result)
+		   evenp (not evenp))
+	     (if evenp (setq before (cdr before)))
+	     (if (eq before list) (error 'circular-list list)))))))
 
 ;;; `copy-list' is implemented as a C primitive, as of 1998-11