* lisp/emacs-lisp/smie.el (smie-prec2->grammar): Fix corner case problem.

2 files changed, 9 insertions, 2 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index b71b55d8477..933e5bbb515 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2015-02-19  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+        * emacs-lisp/smie.el (smie-prec2->grammar): Fix corner case problem.
+
 2015-02-18  Kelly Dean  <kelly@prtime.org>
 
         * register.el (jump-to-register):
diff --git a/lisp/emacs-lisp/smie.el b/lisp/emacs-lisp/smie.el
index 5b9dc6422a2..48bded4e3a6 100644
--- a/lisp/emacs-lisp/smie.el
+++ b/lisp/emacs-lisp/smie.el
@@ -612,8 +612,11 @@ PREC2 is a table as returned by `smie-precs->prec2' or
              (cons (pcase (cdr x)
                      (`closer (cddr (assoc token table)))
                      (`opener (cdr (assoc token table))))))
-        (cl-assert (numberp (car cons)))
-        (setf (car cons) (list (car cons)))))
+        ;; `cons' can be nil for openers/closers which only contain
+        ;; "atomic" elements.
+        (when cons
+          (cl-assert (numberp (car cons)))
+          (setf (car cons) (list (car cons))))))
     (let ((ca (gethash :smie-closer-alist prec2)))
       (when ca (push (cons :smie-closer-alist ca) table)))
     ;; (smie-check-grammar table prec2 'step3)