(find-backup-file-name) [ms-dos]: If support for long

file names is not available, behave as if version-control were set
to never.

diff --git a/lisp/files.el b/lisp/files.el
index 6fc452545e5f4c33c3b5adfc41b26e5170253ef5..904d04636f525aec7a2acfa20edf58726676b60d 100644 (file)
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -2386,7 +2386,11 @@ Uses `backup-directory-alist' in the same way as does
     ;; Run a handler for this function so that ange-ftp can refuse to do it.
     (if handler
        (funcall handler 'find-backup-file-name fn)
-      (if (eq version-control 'never)
+      (if (or (eq version-control 'never)
+             ;; We don't support numbered backups on plain MS-DOS
+             ;; when long file names are unavailable.
+             (and (eq system-type 'ms-dos)
+                  (not (msdos-long-file-names))))
          (list (make-backup-file-name fn))
        (let* ((basic-name (make-backup-file-name-1 fn))
               (base-versions (concat (file-name-nondirectory basic-name)