Fix a bug in cfengine3-mode

* progmodes/cfengine.el (cfengine3-mode): Handle nil
  eldoc-documentation-function.

1 files changed, 4 insertions, 0 deletions

diff --git a/lisp/progmodes/cfengine.el b/lisp/progmodes/cfengine.el
index 27784a503ba..108ccb654c4 100644
--- a/lisp/progmodes/cfengine.el
+++ b/lisp/progmodes/cfengine.el
@@ -1390,6 +1390,10 @@ to the action header."
                  (when buffer-file-name
                    (shell-quote-argument buffer-file-name)))))
 
+  ;; For emacs < 25.1 where `eldoc-documentation-function' defaults to
+  ;; nil.
+  (or eldoc-documentation-function
+      (setq-local eldoc-documentation-function #'ignore))
   (add-function :before-until (local 'eldoc-documentation-function)
                 #'cfengine3-documentation-function)