master df68768d1d8: Avoid errors when "-*- -*-" prop line of a file has no tags

branch: master
commit df68768d1d80ff1c90839b4c1789469b425808d8
Author: Eli Zaretskii <[email protected]>
Commit: Eli Zaretskii <[email protected]>

    Avoid errors when "-*- -*-" prop line of a file has no tags
    
    * lisp/files.el (set-auto-mode): Don't add an invalid "-mode" to
    'modes', if the mode tag is empty.
    (set-auto-mode-1): Make sure we return a position that is at or
    after point.  (Bug#81516)
---
 lisp/files.el | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/lisp/files.el b/lisp/files.el
index 9d5cd3fa30d..8f2d8e97e4b 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -3634,9 +3634,11 @@ we don't actually set it to the same mode the buffer already has."
 		   (push (intern (concat (downcase (buffer-substring beg (point))) "-mode"))
 			 modes)))
 	     ;; Simple -*-MODE-*- case.
-	     (push (intern (concat (downcase (buffer-substring (point) end))
-				   "-mode"))
-		   modes))))
+             (and (< (point) end)
+	          (push (intern (concat (downcase
+                                         (buffer-substring (point) end))
+				        "-mode"))
+		        modes)))))
     (or
      ;; If we found modes to use, invoke them now, outside the save-excursion.
      ;; Presume `modes' holds a major mode followed by minor modes.
@@ -3827,6 +3829,7 @@ have no effect."
        (forward-char -3)
        (skip-chars-backward " \t")
        (setq end (point))
+       (setq beg (min beg end))
        (goto-char beg)
        end))))