(comint-output-filter):

  Revert to using `insert-before-markers'.
  Add bletcherous hack to undo damage caused by `insert-before-markers'.
  Put `front-sticky' property on overlays created here so that the field code
    understands how the overlay works.
  Use a let when making comint-last-prompt-overlay, so that the code is
    easier to read.

2 files changed, 56 insertions, 9 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 3276d946d8b..8b0fba5209b 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,12 @@
+2000-09-13  Miles Bader  <miles@gnu.org>
+
+        * comint.el (comint-output-filter): Revert to using
+        `insert-before-markers'.  Add bletcherous hack to undo damage
+        caused by `insert-before-markers'.  Put `front-sticky' property on
+        overlays created here so that the field code understands how the
+        overlay works.  Use a let when making comint-last-prompt-overlay,
+        so that the code is easier to read.
+
 2000-09-12  Dave Love  <fx@gnu.org>
 
         * simple.el (read-mail-command): Doc fix.
diff --git a/lisp/comint.el b/lisp/comint.el
index e86c019a9d5..4fc8f67402e 100644
--- a/lisp/comint.el
+++ b/lisp/comint.el
@@ -1510,8 +1510,46 @@ This variable is permanent-local.")
             (goto-char (process-mark process))
             (set-marker comint-last-output-start (point))
 
-            (insert string)
-
+            ;; insert-before-markers is a bad thing. XXX
+            ;;
+            ;; It is used here to force window-point markers (used to
+            ;; store the value of point in non-selected windows) to
+            ;; advance, but it also screws up any other markers that we
+            ;; don't _want_ to advance, such as the start-marker of some
+            ;; of the overlays we create.
+            ;;
+            ;; We work around the problem with the overlays by
+            ;; explicitly adjusting them after we do the insertion, but
+            ;; in the future this problem should be solved correctly, by
+            ;; using `insert', and making the insertion-type of
+            ;; window-point markers settable (via a buffer-local
+            ;; variable).  In comint buffers, this variable would be set
+            ;; to `t', to cause point in non-select windows to advance.
+            (insert-before-markers string)
+            ;; Fixup markers and overlays that got screwed up because we
+            ;; used `insert-before-markers'.
+            (let ((old-point (- (point) (length string))))
+              ;; comint-last-output-start marker
+              (set-marker comint-last-output-start old-point)
+              ;; No overlays we create are set to advance upon insertion
+              ;; (at the start/end), so we assume that any overlay which
+              ;; is at the current point was incorrectly advanced by
+              ;; insert-before-markers.  First fixup overlays that might
+              ;; start at point:
+              (dolist (over (overlays-at (point)))
+                (when (= (overlay-start over) (point))
+                  (let ((end (overlay-end over)))
+                    (move-overlay over
+                                  old-point
+                                  (if (= end (point)) old-point end)))))
+              ;; Then do overlays that might end at point:
+              (dolist (over (overlays-at (1- (point))))
+                (when (= (overlay-end over) (point))
+                  (move-overlay over
+                                (min (overlay-start over) old-point)
+                                old-point))))
+
+            ;; Advance process-mark
             (set-marker (process-mark process) (point))
 
             (unless comint-use-prompt-regexp-instead-of-fields
@@ -1528,8 +1566,9 @@ This variable is permanent-local.")
                 ;; Create a new overlay
                 (let ((over (make-overlay comint-last-output-start (point))))
                   (overlay-put over 'field 'output)
-                  (overlay-put over 'rear-nonsticky t)
                   (overlay-put over 'inhibit-line-move-field-capture t)
+                  (overlay-put over 'front-sticky t)
+                  (overlay-put over 'rear-nonsticky t)
                   (overlay-put over 'evaporate t)
                   (setq comint-last-output-overlay over))))
 
@@ -1546,12 +1585,11 @@ This variable is permanent-local.")
                       (move-overlay comint-last-prompt-overlay
                                     prompt-start (point))
                     ;; Need to create the overlay
-                    (setq comint-last-prompt-overlay
-                          (make-overlay prompt-start (point)))
-                    (overlay-put comint-last-prompt-overlay
-                                 'rear-nonsticky t)
-                    (overlay-put comint-last-prompt-overlay
-                                 'face 'comint-highlight-prompt-face)))))
+                    (let ((over (make-overlay prompt-start (point))))
+                      (overlay-put over 'face 'comint-highlight-prompt-face)
+                      (overlay-put over 'front-sticky t)
+                      (overlay-put over 'rear-nonsticky t)
+                      (setq comint-last-prompt-overlay over))))))
 
             ;;(force-mode-line-update)