(comint-displayed-dynamic-completions): New variable.

(comint-dynamic-list-completions): Be more careful about choosing
when to scroll an existing completions window.

2 files changed, 26 insertions, 1 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 28847f723be..b47761de024 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,9 @@
+2002-07-04  Miles Bader  <miles@gnu.org>
+
+        * comint.el (comint-displayed-dynamic-completions): New variable.
+        (comint-dynamic-list-completions): Be more careful about choosing
+        when to scroll an existing completions window.
+
 2002-07-03  Andreas Schwab  <schwab@suse.de>
 
         * net/tramp.el (tramp-handle-ange-ftp): Move interactive spec
diff --git a/lisp/comint.el b/lisp/comint.el
index bdbe2fdb709..3c0be25c199 100644
--- a/lisp/comint.el
+++ b/lisp/comint.el
@@ -2798,13 +2798,29 @@ See also `comint-dynamic-complete-filename'."
        (mapcar 'comint-quote-filename completions)))))
 
 
+;; This is bound locally in a *Completions* buffer to the list of
+;; completions displayed, and is used to detect the case where the same
+;; command is repeatedly used without the set of completions changing.
+(defvar comint-displayed-dynamic-completions nil)
+
 (defun comint-dynamic-list-completions (completions)
   "List in help buffer sorted COMPLETIONS.
 Typing SPC flushes the help buffer."
   (let ((window (get-buffer-window "*Completions*")))
     (if (and (eq last-command this-command)
              window (window-live-p window) (window-buffer window)
-             (buffer-name (window-buffer window)))
+             (buffer-name (window-buffer window))
+             ;; The above tests are not sufficient to detect the case where we
+             ;; should scroll, because the top-level interactive command may
+             ;; not have displayed a completions window the last time it was
+             ;; invoked, and there may be such a window left over from a
+             ;; previous completion command with a different set of
+             ;; completions.  To detect that case, we also test that the set
+             ;; of displayed completions is in fact the same as the previously
+             ;; displayed set.
+             (equal completions
+                    (buffer-local-value 'comint-displayed-dynamic-completions
+                                        (window-buffer window))))
         ;; If this command was repeated, and
         ;; there's a fresh completion window with a live buffer,
         ;; and this command is repeated, scroll that window.
@@ -2822,6 +2838,9 @@ Typing SPC flushes the help buffer."
         (let (key first)
           (if (save-excursion
                 (set-buffer (get-buffer "*Completions*"))
+                (set (make-local-variable
+                      'comint-displayed-dynamic-completions)
+                     completions)
                 (setq key (read-key-sequence nil)
                       first (aref key 0))
                 (and (consp first) (consp (event-start first))