(tex-guess-main-file): Handle the case where one of the buffers is narrowed.

1 files changed, 4 insertions, 2 deletions

diff --git a/lisp/textmodes/tex-mode.el b/lisp/textmodes/tex-mode.el
index 465cb98c047..43a26cf2296 100644
--- a/lisp/textmodes/tex-mode.el
+++ b/lisp/textmodes/tex-mode.el
@@ -1410,8 +1410,10 @@ ALL other buffers."
                      ;; (or (easy-mmode-derived-mode-p 'latex-mode)
                      ;;          (easy-mmode-derived-mode-p 'plain-tex-mode))
                      (save-excursion
-                       (goto-char (point-min))
-                       (re-search-forward header-re 10000 t)))
+                       (save-restriction
+                         (widen)
+                         (goto-char (point-min))
+                         (re-search-forward header-re 10000 t))))
             (throw 'found (expand-file-name buffer-file-name))))))))
 
 (defun tex-main-file ()