*** empty log message ***

1 files changed, 19 insertions, 7 deletions

diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index 62a112debca..008a9967322 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -604,7 +604,10 @@
          (condition-case ()
              (eval form)
            (error form)))
-        ((null (cdr (cdr form))) (nth 1 form))
+;;; It is not safe to delete the function entirely
+;;; (actually, it would be safe if we know the sole arg
+;;; is not a marker).
+;;      ((null (cdr (cdr form))) (nth 1 form))
         (t form)))
 
 (defun byte-optimize-minus (form)
@@ -621,19 +624,27 @@
                 (numberp last))
            (setq form (nconc (list '- (- (nth 1 form) last) (nth 2 form))
                              (delq last (copy-sequence (nthcdr 3 form))))))))
-  (if (eq (nth 2 form) 0)
-      (nth 1 form)                      ; (- x 0)  -->  x
+;;; It is not safe to delete the function entirely
+;;; (actually, it would be safe if we know the sole arg
+;;; is not a marker).
+;;;  (if (eq (nth 2 form) 0)
+;;;      (nth 1 form)                   ; (- x 0)  -->  x
     (byte-optimize-predicate
      (if (and (null (cdr (cdr (cdr form))))
               (eq (nth 1 form) 0))      ; (- 0 x)  -->  (- x)
          (cons (car form) (cdr (cdr form)))
-       form))))
+       form))
+;;;    )
+  )
 
 (defun byte-optimize-multiply (form)
   (setq form (byte-optimize-delay-constants-math form 1 '*))
   ;; If there is a constant in FORM, it is now the last element.
   (cond ((null (cdr form)) 1)
-        ((null (cdr (cdr form))) (nth 1 form))
+;;; It is not safe to delete the function entirely
+;;; (actually, it would be safe if we know the sole arg
+;;; is not a marker or if it appears in other arithmetic).
+;;;     ((null (cdr (cdr form))) (nth 1 form))
         ((let ((last (car (reverse form))))
            (cond ((eq 0 last)  (list 'progn (cdr form)))
                  ((eq 1 last)  (delq 1 (copy-sequence form)))
@@ -659,8 +670,9 @@
                                 (cons (/ (nth 1 form) last)
                                       (byte-compile-butlast (cdr (cdr form)))))
                      last nil))))
-    (cond ((null (cdr (cdr form)))
-           (nth 1 form))
+    (cond 
+;;;       ((null (cdr (cdr form)))
+;;;        (nth 1 form))
           ((eq (nth 1 form) 0)
            (append '(progn) (cdr (cdr form)) '(0)))
           ((eq last -1)