Prevent for consing in cl-mapc and cl-mapl

* lisp/emacs-lisp/cl-extra.el (cl--mapcar-many): Add optional arg ACC;
If non-nil, accumulate values in the result (Bug#25826).
(cl-mapc): Do computations inside function instead of call cl-map.
(cl-mapl): Do computations inside function instead of call cl-maplist.
* lisp/emacs-lisp/cl-lib.el (mapcar): Add autoload cookie.
Call cl--mapcar-many with non-nil 3rd argument.
* test/lisp/emacs-lisp/cl-extra-tests.el (cl-extra-test-map)
(cl-extra-test-mapc, cl-extra-test-mapcar, cl-extra-test-mapl)
(cl-extra-test-maplist): New tests.

1 files changed, 3 insertions, 2 deletions

diff --git a/lisp/emacs-lisp/cl-lib.el b/lisp/emacs-lisp/cl-lib.el
index 5aa8f1bf652..8c4455a3dad 100644
--- a/lisp/emacs-lisp/cl-lib.el
+++ b/lisp/emacs-lisp/cl-lib.el
@@ -347,8 +347,9 @@ Call `cl-float-limits' to set this.")
 
 (cl--defalias 'cl-copy-seq 'copy-sequence)
 
-(declare-function cl--mapcar-many "cl-extra" (cl-func cl-seqs))
+(declare-function cl--mapcar-many "cl-extra" (cl-func cl-seqs &optional acc))
 
+;;;###autoload
 (defun cl-mapcar (cl-func cl-x &rest cl-rest)
   "Apply FUNCTION to each element of SEQ, and make a list of the results.
 If there are several SEQs, FUNCTION is called with that many arguments,
@@ -358,7 +359,7 @@ SEQ, this is like `mapcar'.  With several, it is like the Common Lisp
 \n(fn FUNCTION SEQ...)"
   (if cl-rest
       (if (or (cdr cl-rest) (nlistp cl-x) (nlistp (car cl-rest)))
-	  (cl--mapcar-many cl-func (cons cl-x cl-rest))
+	  (cl--mapcar-many cl-func (cons cl-x cl-rest) 'accumulate)
 	(let ((cl-res nil) (cl-y (car cl-rest)))
 	  (while (and cl-x cl-y)
 	    (push (funcall cl-func (pop cl-x) (pop cl-y)) cl-res))