* lisp/emacs-lisp/cl-macs.el (cl--transform-lambda): Defend against

potential binding of print-gensym to t, and prettify (back)quotes in
case they appear in args's default values.

Fixes: debbugs:12884

2 files changed, 11 insertions, 3 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 01b7532e56d..1a86637f4ed 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2012-11-15  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * emacs-lisp/cl-macs.el (cl--transform-lambda): Defend against
+        potential binding of print-gensym to t, and prettify (back)quotes in
+        case they appear in args's default values (bug#12884).
+
 2012-11-14  Stefan Monnier  <monnier@iro.umontreal.ca>
 
         * emacs-lisp/nadvice.el: Add around advice for interactive specs.
diff --git a/lisp/emacs-lisp/cl-macs.el b/lisp/emacs-lisp/cl-macs.el
index 3c46c40242d..f83bfe00666 100644
--- a/lisp/emacs-lisp/cl-macs.el
+++ b/lisp/emacs-lisp/cl-macs.el
@@ -260,9 +260,11 @@ The name is made by appending a number to PREFIX, default \"G\"."
                         (require 'help-fns)
                         (cons (help-add-fundoc-usage
                                (if (stringp (car hdr)) (pop hdr))
-                               (format "%S"
-                                       (cons 'fn
-                                             (cl--make-usage-args orig-args))))
+                               ;; Be careful with make-symbol and (back)quote,
+                               ;; see bug#12884.
+                               (let ((print-gensym nil) (print-quoted t))
+                                 (format "%S" (cons 'fn (cl--make-usage-args
+                                                         orig-args)))))
                               hdr)))
                     (list `(let* ,cl--bind-lets
                              ,@(nreverse cl--bind-forms)