(comint-next-prompt): Don't loop infinitely if

{next,previous}-single-char-property-change returns its input position
when the search fails.

1 files changed, 9 insertions, 2 deletions

diff --git a/lisp/comint.el b/lisp/comint.el
index 3b0ccfc0890..29897a92c58 100644
--- a/lisp/comint.el
+++ b/lisp/comint.el
@@ -2140,14 +2140,21 @@ occurance of text matching `comint-prompt-regexp'."
         (comint-skip-prompt))
     ;; Use input fields
     (let ((pos (point))
-          (input-pos nil))
+          (input-pos nil)
+          prev-pos)
       (while (/= n 0)
+        (setq prev-pos pos)
         (setq pos
               (if (> n 0)
                   (next-single-char-property-change pos 'field)
                 (previous-single-char-property-change pos 'field)))
-        (cond ((null pos)
+        (cond ((or (null pos) (= pos prev-pos))
                ;; Ran off the end of the buffer.
+               (when (> n 0)
+                 ;; There's always an input field at the end of the
+                 ;; buffer, but it has a `field' property of nil.
+                 (setq input-pos (point-max)))
+               ;; stop iterating
                (setq n 0))
               ((eq (get-char-property pos 'field) 'input)
                (setq n (if (< n 0) (1+ n) (1- n)))