master e125d4b820: Small fix in font-lock-extend-region-multiline

[Lars Ingebrigtsen]

branch: master
commit e125d4b8207a330133e49263551bb85cd1e4fd31
Author: Sébastien Miquel <sebastien.miquel@posteo.eu>
Commit: Lars Ingebrigtsen <larsi@gnus.org>

    Small fix in font-lock-extend-region-multiline
    
    * lisp/font-lock.el (font-lock-extend-region-multiline): Do not
    extend the region if `font-lock-multiline' starts at
    `font-lock-end' (bug#46558).
---
 lisp/font-lock.el | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/lisp/font-lock.el b/lisp/font-lock.el
index 488874a175..df0a26f4d0 100644
--- a/lisp/font-lock.el
+++ b/lisp/font-lock.el
@@ -1245,12 +1245,17 @@ Put first the functions more likely to cause a change 
and cheaper to compute.")
       (setq font-lock-beg (or (previous-single-property-change
                                font-lock-beg 'font-lock-multiline)
                               (point-min))))
-    ;;
-    (when (get-text-property font-lock-end 'font-lock-multiline)
-      (setq changed t)
-      (setq font-lock-end (or (text-property-any font-lock-end (point-max)
-                                                 'font-lock-multiline nil)
-                              (point-max))))
+    ;; If `font-lock-multiline' starts at `font-lock-end', do not
+    ;; extend the region.
+    (let ((before-end (max (point-min) (1- font-lock-end)))
+          (new-end nil))
+      (when (get-text-property before-end 'font-lock-multiline)
+        (setq new-end (or (text-property-any before-end (point-max)
+                                             'font-lock-multiline nil)
+                          (point-max)))
+        (when (/= new-end font-lock-end)
+          (setq changed t)
+          (setq font-lock-end new-end))))
     changed))
 
 (defun font-lock-extend-region-wholelines ()