Fix slow abbrev expansion in `message-mode' in some circumstances

* lisp/gnus/message.el (message--syntax-propertize): Use the
correct Message mode syntax table to avoid having
`message-cite-prefix-regexp' trigger very heavy backtracing when
called from an abbrev context (which defines "_" as a word
constituent) (bug#45944).

diff --git a/lisp/gnus/message.el b/lisp/gnus/message.el
index 50e0218748424d887ad18f4a4da3b2bc3d4ccba8..b22b4543e71982640e6c439be267d7e5c50c3230 100644 (file)
--- a/lisp/gnus/message.el
+++ b/lisp/gnus/message.el
@@ -3057,22 +3057,23 @@ See also `message-forbidden-properties'."
 
 (defun message--syntax-propertize (beg end)
   "Syntax-propertize certain message text specially."
-  (let ((citation-regexp (concat "^" message-cite-prefix-regexp ".*$"))
-        (smiley-regexp (regexp-opt message-smileys)))
-    (goto-char beg)
-    (while (search-forward-regexp citation-regexp
-                                  end 'noerror)
-      (let ((start (match-beginning 0))
-            (end (match-end 0)))
-        (add-text-properties start (1+ start)
-                             `(syntax-table ,(string-to-syntax "<")))
-        (add-text-properties end (min (1+ end) (point-max))
-                             `(syntax-table ,(string-to-syntax ">")))))
-    (goto-char beg)
-    (while (search-forward-regexp smiley-regexp
-            end 'noerror)
-      (add-text-properties (match-beginning 0) (match-end 0)
-                           `(syntax-table ,(string-to-syntax "."))))))
+  (with-syntax-table message-mode-syntax-table
+    (let ((citation-regexp (concat "^" message-cite-prefix-regexp ".*$"))
+          (smiley-regexp (regexp-opt message-smileys)))
+      (goto-char beg)
+      (while (search-forward-regexp citation-regexp
+                                    end 'noerror)
+       (let ((start (match-beginning 0))
+              (end (match-end 0)))
+          (add-text-properties start (1+ start)
+                               `(syntax-table ,(string-to-syntax "<")))
+          (add-text-properties end (min (1+ end) (point-max))
+                               `(syntax-table ,(string-to-syntax ">")))))
+      (goto-char beg)
+      (while (search-forward-regexp smiley-regexp
+                                   end 'noerror)
+       (add-text-properties (match-beginning 0) (match-end 0)
+                             `(syntax-table ,(string-to-syntax ".")))))))
 
 ;;;###autoload
 (define-derived-mode message-mode text-mode "Message"