Fix return values of switch-to-prev/next-buffer.

* window.el (switch-to-prev-buffer, switch-to-next-buffer):
Don't return a non-nil value when no suitable buffer was found.

2 files changed, 30 insertions, 20 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 20b31e1f9f4..d56963ac5b0 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2012-07-31  Martin Rudalics  <rudalics@gmx.at>
+
+        * window.el (switch-to-prev-buffer, switch-to-next-buffer):
+        Don't return a non-nil value when no suitable buffer was found.
+
 2012-07-31  Fabián Ezequiel Gallina  <fgallina@cuca>
 
         * progmodes/python.el (run-python-internal): Disable font lock for
diff --git a/lisp/window.el b/lisp/window.el
index d58fa81a8de..910164043d9 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -2669,6 +2669,8 @@ that is already visible in another window on the same frame."
 (defun switch-to-prev-buffer (&optional window bury-or-kill)
   "In WINDOW switch to previous buffer.
 WINDOW must be a live window and defaults to the selected one.
+Return the buffer switched to, nil if no suitable buffer could be
+found.
 
 Optional argument BURY-OR-KILL non-nil means the buffer currently
 shown in WINDOW is about to be buried or killed and consequently
@@ -2679,7 +2681,7 @@ shall not be switched to in future invocations of this command."
          (old-buffer (window-buffer window))
          ;; Save this since it's destroyed by `set-window-buffer'.
          (next-buffers (window-next-buffers window))
-         entry new-buffer killed-buffers visible)
+         entry buffer new-buffer killed-buffers visible)
     (when (window-dedicated-p window)
       (error "Window %s is dedicated to buffer %s" window old-buffer))
 
@@ -2687,20 +2689,20 @@ shall not be switched to in future invocations of this command."
       ;; Scan WINDOW's previous buffers first, skipping entries of next
       ;; buffers.
       (dolist (entry (window-prev-buffers window))
-        (when (and (setq new-buffer (car entry))
-                   (or (buffer-live-p new-buffer)
+        (when (and (setq buffer (car entry))
+                   (or (buffer-live-p buffer)
                        (not (setq killed-buffers
-                                  (cons new-buffer killed-buffers))))
-                   (not (eq new-buffer old-buffer))
-                   (or bury-or-kill
-                       (not (memq new-buffer next-buffers))))
+                                  (cons buffer killed-buffers))))
+                   (not (eq buffer old-buffer))
+                   (or bury-or-kill (not (memq buffer next-buffers))))
           (if (and (not switch-to-visible-buffer)
-                   (get-buffer-window new-buffer frame))
+                   (get-buffer-window buffer frame))
               ;; Try to avoid showing a buffer visible in some other window.
-              (setq visible new-buffer)
-          (set-window-buffer-start-and-point
-           window new-buffer (nth 1 entry) (nth 2 entry))
-          (throw 'found t))))
+              (setq visible buffer)
+            (setq new-buffer buffer)
+            (set-window-buffer-start-and-point
+             window new-buffer (nth 1 entry) (nth 2 entry))
+            (throw 'found t))))
       ;; Scan reverted buffer list of WINDOW's frame next, skipping
       ;; entries of next buffers.  Note that when we bury or kill a
       ;; buffer we don't reverse the global buffer list to avoid showing
@@ -2767,13 +2769,15 @@ shall not be switched to in future invocations of this command."
 
 (defun switch-to-next-buffer (&optional window)
   "In WINDOW switch to next buffer.
-WINDOW must be a live window and defaults to the selected one."
+WINDOW must be a live window and defaults to the selected one.
+Return the buffer switched to, nil if no suitable buffer could be
+found."
   (interactive)
   (let* ((window (window-normalize-window window t))
          (frame (window-frame window))
          (old-buffer (window-buffer window))
          (next-buffers (window-next-buffers window))
-         new-buffer entry killed-buffers visible)
+         buffer new-buffer entry killed-buffers visible)
     (when (window-dedicated-p window)
       (error "Window %s is dedicated to buffer %s" window old-buffer))
 
@@ -2804,16 +2808,17 @@ WINDOW must be a live window and defaults to the selected one."
       ;; Scan WINDOW's reverted previous buffers last (must not use
       ;; nreverse here!)
       (dolist (entry (reverse (window-prev-buffers window)))
-        (when (and (setq new-buffer (car entry))
-                   (or (buffer-live-p new-buffer)
+        (when (and (setq buffer (car entry))
+                   (or (buffer-live-p buffer)
                        (not (setq killed-buffers
-                                  (cons new-buffer killed-buffers))))
-                   (not (eq new-buffer old-buffer)))
+                                  (cons buffer killed-buffers))))
+                   (not (eq buffer old-buffer)))
           (if (and (not switch-to-visible-buffer)
-                   (get-buffer-window new-buffer frame))
+                   (get-buffer-window buffer frame))
               ;; Try to avoid showing a buffer visible in some other window.
               (unless visible
-                (setq visible new-buffer))
+                (setq visible buffer))
+            (setq new-buffer buffer)
             (set-window-buffer-start-and-point
              window new-buffer (nth 1 entry) (nth 2 entry))
             (throw 'found t))))