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, 3 insertions, 6 deletions

diff --git a/lisp/progmodes/gud.el b/lisp/progmodes/gud.el
index 4e31c5e827c..6076f88dea6 100644
--- a/lisp/progmodes/gud.el
+++ b/lisp/progmodes/gud.el
@@ -3387,9 +3387,6 @@ ACTIVATEP non-nil means activate mouse motion events."
 
 ;;; Tips for `gud'
 
-(defvar gud-tooltip-original-filter nil
-  "Process filter to restore after GUD output has been received.")
-
 (defvar gud-tooltip-dereference nil
   "Non-nil means print expressions with a `*' in front of them.
 For C this would dereference a pointer expression.")
@@ -3423,7 +3420,7 @@ With arg, dereference expr if ARG is positive, otherwise do not dereference."
 ; gdb-mi.el gets round this problem.
 (defun gud-tooltip-process-output (process output)
   "Process debugger output and show it in a tooltip window."
-  (set-process-filter process gud-tooltip-original-filter)
+  (remove-function (process-filter process) #'gud-tooltip-process-output)
   (tooltip-show (tooltip-strip-prompt process output)
 		(or gud-tooltip-echo-area tooltip-use-echo-area)))
 
@@ -3490,8 +3487,8 @@ so they have been disabled."))
                       (gdb-input
 		       (concat cmd "\n")
 		       `(lambda () (gdb-tooltip-print ,expr))))
-		  (setq gud-tooltip-original-filter (process-filter process))
-		  (set-process-filter process 'gud-tooltip-process-output)
+                  (add-function :override (process-filter process)
+                                #'gud-tooltip-process-output)
 		  (gud-basic-call cmd))
 		expr))))))))