bug#13248: [PATCH] bug#13248: 24.2.50; select-window moves point (in comint-postoutput-scroll-to-bottom)

[Vitalie Spinu]

  >> martin rudalics <rudalics@gmx.at>
  >> on Fri, 21 Dec 2012 15:25:07 +0100 wrote:

[...]

  >> So the point is clearly moved in select-window. Moreover the (point)
  >> equals (window-end) just before select-window is called, so it is
  >> visible. Consequently, the following (comint-adjust-point selected) is
  >> completely screwed because it relies on point *not* being moved!

[...]

  >> 
  >> The variable `comint-scroll-show-maximum-output' is the default t, this
  >> is why comint runs `comint-postoutput-scroll-to-bottom' in its
  >> `comint-output-filter-functions'.
  >> 
  >> I can propose a patch for commit to reset the point, 

[...]

Here is a patch of the comint-postoutput-scroll-to-bottom to circumvent
resetting the point on select-window. 

    Thanks, 
    Vitalie

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 6d5e77d..dc5a4be 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2012-12-24  Vitalie Spinu  <spinuvit@gmail.com>
+
+       * comint.el (comint-postoutput-scroll-to-bottom): Don't reset
+       buffer point on select-window (Bug#13248).
+
 2012-12-24  Dmitry Gutov  <dgutov@yandex.ru>
 
        * progmodes/ruby-mode.el: Bump the version to 1.2 (Bug#13200).
diff --git a/lisp/comint.el b/lisp/comint.el
index cff9afe..fa3764d 100644
--- a/lisp/comint.el
+++ b/lisp/comint.el
@@ -2120,12 +2120,14 @@ This function should be in the list 
`comint-output-filter-functions'."
         ((bound-and-true-p follow-mode)
          (follow-comint-scroll-to-bottom))
         (t
-         (let ((selected (selected-window)))
+         (let ((selected (selected-window))
+                ;; select-window resets point; thus, save
+                (old-point (point)))
            (dolist (w (get-buffer-window-list current nil t))
              (select-window w)
              (unwind-protect
                  (progn
-                   (comint-adjust-point selected)
+                   (comint-adjust-point selected old-point)
                    ;; Optionally scroll to the bottom of the window.
                    (and comint-scroll-show-maximum-output
                         (eobp)
@@ -2133,9 +2135,12 @@ This function should be in the list 
`comint-output-filter-functions'."
                (select-window selected))))))
       (set-buffer current))))
 
-(defun comint-adjust-point (selected)
+(defun comint-adjust-point (selected &optional saved-point)
   "Move point in the selected window based on Comint settings.
-SELECTED is the window that was originally selected."
+SELECTED is the window that was originally selected.
+
+If SAVED-POINT is given, use it as reference instead of the
+current point."
   (let ((process (get-buffer-process (current-buffer))))
     (and (< (point) (process-mark process))
         (or (memq comint-move-point-for-output '(t all))
@@ -2144,7 +2149,8 @@ SELECTED is the window that was originally selected."
                 (if (eq (selected-window) selected) 'this 'others))
             ;; If point was at the end, keep it at end.
             (and (marker-position comint-last-output-start)
-                 (>= (point) comint-last-output-start)))
+                 (>= (or saved-point (point))
+                      comint-last-output-start)))
         (goto-char (process-mark process)))))
 
 (defun comint-truncate-buffer (&optional _string)