* lisp/erc/erc-track.el (erc-modified-channels-display): Update all mode lines

if needed.  Remove call to erc-modified-channels-object
where we ignored the return value.
(erc-modified-channels-update): Don't force-mode-line-update here any more.

Fixes: debbugs:18510

2 files changed, 47 insertions, 39 deletions

diff --git a/lisp/erc/ChangeLog b/lisp/erc/ChangeLog
index 6d99fdf73d9..b3cdb067d13 100644
--- a/lisp/erc/ChangeLog
+++ b/lisp/erc/ChangeLog
@@ -1,3 +1,10 @@
+2014-09-24  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * erc-track.el (erc-modified-channels-display): Update all mode lines
+        if needed (bug#18510).  Remove call to erc-modified-channels-object
+        where we ignored the return value.
+        (erc-modified-channels-update): Don't force-mode-line-update here any more.
+
 2014-02-25  Julien Danjou  <julien@danjou.info>
 
         * erc-networks.el (erc-determine-network): Check that NETWORK as a
diff --git a/lisp/erc/erc-track.el b/lisp/erc/erc-track.el
index 3f7b6a7b501..706cce2fefe 100644
--- a/lisp/erc/erc-track.el
+++ b/lisp/erc/erc-track.el
@@ -767,8 +767,7 @@ ARGS are ignored."
                   (erc-modified-channels-remove-buffer buffer))))
             erc-modified-channels-alist)
       (when removed-channel
-        (erc-modified-channels-display)
-        (force-mode-line-update t)))
+        (erc-modified-channels-display)))
     (remove-hook 'post-command-hook 'erc-modified-channels-update)))
 
 (defvar erc-track-mouse-face (if (featurep 'xemacs)
@@ -825,43 +824,45 @@ Use `erc-make-mode-line-buffer-name' to create buttons."
         ((eq 'importance erc-track-switch-direction)
          (erc-track-sort-by-importance)))
   (run-hooks 'erc-track-list-changed-hook)
-  (unless (eq erc-track-position-in-mode-line nil)
-  (if (null erc-modified-channels-alist)
-      (setq erc-modified-channels-object (erc-modified-channels-object nil))
-    ;; erc-modified-channels-alist contains all the data we need.  To
-    ;; better understand what is going on, we split things up into
-    ;; four lists: BUFFERS, COUNTS, SHORT-NAMES, and FACES.  These
-    ;; four lists we use to create a new
-    ;; `erc-modified-channels-object' using
-    ;; `erc-make-mode-line-buffer-name'.
-    (let* ((buffers (mapcar 'car erc-modified-channels-alist))
-           (counts (mapcar 'cadr erc-modified-channels-alist))
-           (faces (mapcar 'cddr erc-modified-channels-alist))
-           (long-names (mapcar #'(lambda (buf)
-                                   (or (buffer-name buf)
-                                       ""))
-                               buffers))
-           (short-names (if (functionp erc-track-shorten-function)
-                            (funcall erc-track-shorten-function
-                                     long-names)
-                          long-names))
-           strings)
-      (while buffers
-        (when (car short-names)
-          (setq strings (cons (erc-make-mode-line-buffer-name
-                               (car short-names)
-                               (car buffers)
-                               (car faces)
-                               (car counts))
-                              strings)))
-        (setq short-names (cdr short-names)
-              buffers (cdr buffers)
-              counts (cdr counts)
-              faces (cdr faces)))
-      (when (featurep 'xemacs)
-        (erc-modified-channels-object nil))
-      (setq erc-modified-channels-object
-            (erc-modified-channels-object strings))))))
+  (when erc-track-position-in-mode-line
+    (let* ((oldobject erc-modified-channels-object)
+           (strings
+            (when erc-modified-channels-alist
+              ;; erc-modified-channels-alist contains all the data we need.  To
+              ;; better understand what is going on, we split things up into
+              ;; four lists: BUFFERS, COUNTS, SHORT-NAMES, and FACES.  These
+              ;; four lists we use to create a new
+              ;; `erc-modified-channels-object' using
+              ;; `erc-make-mode-line-buffer-name'.
+              (let* ((buffers (mapcar 'car erc-modified-channels-alist))
+                     (counts (mapcar 'cadr erc-modified-channels-alist))
+                     (faces (mapcar 'cddr erc-modified-channels-alist))
+                     (long-names (mapcar #'(lambda (buf)
+                                             (or (buffer-name buf)
+                                                 ""))
+                                         buffers))
+                     (short-names (if (functionp erc-track-shorten-function)
+                                      (funcall erc-track-shorten-function
+                                               long-names)
+                                    long-names))
+                     strings)
+                (while buffers
+                  (when (car short-names)
+                    (setq strings (cons (erc-make-mode-line-buffer-name
+                                         (car short-names)
+                                         (car buffers)
+                                         (car faces)
+                                         (car counts))
+                                        strings)))
+                  (setq short-names (cdr short-names)
+                        buffers (cdr buffers)
+                        counts (cdr counts)
+                        faces (cdr faces)))
+                strings)))
+           (newobject (erc-modified-channels-object strings)))
+      (unless (equal oldobject newobject)
+        (setq erc-modified-channels-object newobject)
+        (force-mode-line-update t)))))
 
 (defun erc-modified-channels-remove-buffer (buffer)
   "Remove BUFFER from `erc-modified-channels-alist'."