Use add/remove-function to manipulate process-filters.

* lisp/emacs-lisp/nadvice.el (advice--where-alist): Add :override.
(remove-function): Autoload.

* lisp/comint.el (comint-redirect-original-filter-function): Remove.
(comint-redirect-cleanup, comint-redirect-send-command-to-process):
* lisp/vc/vc-cvs.el (vc-cvs-annotate-process-filter,vc-cvs-annotate-command):
* lisp/progmodes/octave-inf.el (inferior-octave-send-list-and-digest):
* lisp/progmodes/prolog.el (prolog-consult-compile):
* lisp/progmodes/gdb-mi.el (gdb, gdb--check-interpreter):
Use add/remove-function instead.
* lisp/progmodes/gud.el (gud-tooltip-original-filter): Remove.
(gud-tooltip-process-output, gud-tooltip-tips):
Use add/remove-function instead.
* lisp/progmodes/xscheme.el (xscheme-previous-process-state): Remove.
(scheme-interaction-mode, exit-scheme-interaction-mode):
Use add/remove-function instead.

* lisp/vc/vc-dispatcher.el: Use lexical-binding.
(vc--process-sentinel): Rename from vc-process-sentinel.
Change last arg to be the code to run.  Don't use vc-previous-sentinel
and vc-sentinel-commands any more.
(vc-exec-after): Allow code to be a function.  Use add/remove-function.
(compilation-error-regexp-alist, view-old-buffer-read-only): Declare.

1 files changed, 15 insertions, 24 deletions

diff --git a/lisp/progmodes/xscheme.el b/lisp/progmodes/xscheme.el
index 2ad44b4b1c8..37c3cd37a6c 100644
--- a/lisp/progmodes/xscheme.el
+++ b/lisp/progmodes/xscheme.el
@@ -35,7 +35,6 @@
 ;;;; Internal Variables
 
 (defvar xscheme-previous-mode)
-(defvar xscheme-previous-process-state)
 (defvar xscheme-last-input-end)
 
 (defvar xscheme-process-command-line nil
@@ -388,8 +387,6 @@ with no args, if that value is non-nil.
   (if (not preserve)
       (let ((previous-mode major-mode))
         (kill-all-local-variables)
-        (make-local-variable 'xscheme-process-name)
-        (make-local-variable 'xscheme-previous-process-state)
         (make-local-variable 'xscheme-runlight-string)
         (make-local-variable 'xscheme-runlight)
         (set (make-local-variable 'xscheme-previous-mode) previous-mode)
@@ -397,35 +394,29 @@ with no args, if that value is non-nil.
           (set (make-local-variable 'xscheme-buffer-name) (buffer-name buffer))
           (set (make-local-variable 'xscheme-last-input-end) (make-marker))
           (let ((process (get-buffer-process buffer)))
-            (if process
-                (progn
-                  (setq xscheme-process-name (process-name process))
-                  (setq xscheme-previous-process-state
-                        (cons (process-filter process)
-                              (process-sentinel process)))
-		  (xscheme-process-filter-initialize t)
-		  (xscheme-mode-line-initialize xscheme-buffer-name)
-		  (set-process-sentinel process 'xscheme-process-sentinel)
-		  (set-process-filter process 'xscheme-process-filter))
-                (setq xscheme-previous-process-state (cons nil nil)))))))
+            (when process
+              (setq-local xscheme-process-name (process-name process))
+              ;; FIXME: Use add-function!
+              (xscheme-process-filter-initialize t)
+              (xscheme-mode-line-initialize xscheme-buffer-name)
+              (add-function :override (process-sentinel process)
+                            #'xscheme-process-sentinel)
+              (add-function :override (process-filter process)
+                            #'xscheme-process-filter))))))
   (scheme-interaction-mode-initialize)
   (scheme-mode-variables)
   (run-mode-hooks 'scheme-mode-hook 'scheme-interaction-mode-hook))
 
 (defun exit-scheme-interaction-mode ()
-  "Take buffer out of scheme interaction mode"
+  "Take buffer out of scheme interaction mode."
   (interactive)
   (if (not (derived-mode-p 'scheme-interaction-mode))
       (error "Buffer not in scheme interaction mode"))
-  (let ((previous-state xscheme-previous-process-state))
-    (funcall xscheme-previous-mode)
-    (let ((process (get-buffer-process (current-buffer))))
-      (if process
-	  (progn
-	    (if (eq (process-filter process) 'xscheme-process-filter)
-		(set-process-filter process (car previous-state)))
-	    (if (eq (process-sentinel process) 'xscheme-process-sentinel)
-		(set-process-sentinel process (cdr previous-state))))))))
+  (funcall xscheme-previous-mode)
+  (let ((process (get-buffer-process (current-buffer))))
+    (when process
+      (remove-function (process-sentinel process) #'xscheme-process-sentinel)
+      (remove-function (process-filter process) #'xscheme-process-filter))))
 
 (defvar scheme-interaction-mode-commands-alist nil)
 (defvar scheme-interaction-mode-map nil)