* lisp/comint.el (comint-after-pmark-p): Check if buffer has a live process.

Return nil if not.
(comint-history-isearch-setup): Don't check if process is live.
Always check if shell prompt is empty regardless of the value
of comint-history-isearch. (Bug#30187)

1 files changed, 16 insertions, 13 deletions

diff --git a/lisp/comint.el b/lisp/comint.el
index b4fbfc86ed9..3163afeff40 100644
--- a/lisp/comint.el
+++ b/lisp/comint.el
@@ -1448,17 +1448,18 @@ If nil, Isearch operates on the whole comint buffer."
 (defun comint-history-isearch-setup ()
   "Set up a comint for using Isearch to search the input history.
 Intended to be added to `isearch-mode-hook' in `comint-mode'."
-  (when (and (get-buffer-process (current-buffer))
-             (or (eq comint-history-isearch t)
-                 (and (eq comint-history-isearch 'dwim)
-                      ;; Point is at command line.
-                      (comint-after-pmark-p)
-                      ;; Prompt is not empty like in Async Shell Command buffers
-                      (not (eq (save-excursion
-                                 (goto-char (comint-line-beginning-position))
-                                 (forward-line 0)
-                                 (point))
-                               (comint-line-beginning-position))))))
+  (when (and
+         ;; Prompt is not empty like in Async Shell Command buffers
+         ;; or in finished shell buffers
+         (not (eq (save-excursion
+                    (goto-char (comint-line-beginning-position))
+                    (forward-line 0)
+                    (point))
+                  (comint-line-beginning-position)))
+         (or (eq comint-history-isearch t)
+             (and (eq comint-history-isearch 'dwim)
+                  ;; Point is at command line.
+                  (comint-after-pmark-p))))
     (setq isearch-message-prefix-add "history ")
     (setq-local isearch-search-fun-function
                 #'comint-history-isearch-search)
@@ -2288,8 +2289,10 @@ If this takes us past the end of the current line, don't skip at all."
 
 (defun comint-after-pmark-p ()
   "Return t if point is after the process output marker."
-  (let ((pmark (process-mark (get-buffer-process (current-buffer)))))
-    (<= (marker-position pmark) (point))))
+  (let ((process (get-buffer-process (current-buffer))))
+    (when process
+      (let ((pmark (process-mark process)))
+        (<= (marker-position pmark) (point))))))
 
 (defun comint-simple-send (proc string)
   "Default function for sending to PROC input STRING.