Improve stability of message-hide-headers

* message.el (message-hide-headers): Use a pointer instead of tracking
the "end-of-headers" point manually (bug#53991).

1 files changed, 8 insertions, 11 deletions

diff --git a/lisp/gnus/message.el b/lisp/gnus/message.el
index 869ab3f82b7..800c7dcea03 100644
--- a/lisp/gnus/message.el
+++ b/lisp/gnus/message.el
@@ -8625,26 +8625,23 @@ From headers in the original article."
 		   message-hidden-headers))
 	(inhibit-point-motion-hooks t)
 	(inhibit-modification-hooks t)
-	(end-of-headers (point-min)))
+	end-of-headers)
     (when regexps
       (save-excursion
 	(save-restriction
 	  (message-narrow-to-headers)
+          (setq end-of-headers (point-min-marker))
 	  (goto-char (point-min))
 	  (while (not (eobp))
 	    (if (not (message-hide-header-p regexps))
 		(message-next-header)
-	      (let ((begin (point))
-		    header header-len)
+	      (let ((begin (point)))
 		(message-next-header)
-		(setq header (buffer-substring begin (point))
-		      header-len (- (point) begin))
-		(delete-region begin (point))
-		(goto-char end-of-headers)
-		(insert header)
-		(setq end-of-headers
-		      (+ end-of-headers header-len))))))))
-    (narrow-to-region end-of-headers (point-max))))
+                (let ((header (delete-and-extract-region begin (point))))
+                  (save-excursion
+                    (goto-char end-of-headers)
+                    (insert-before-markers header))))))))
+      (narrow-to-region end-of-headers (point-max)))))
 
 (defun message-hide-header-p (regexps)
   (let ((result nil)