From: Stefan Monnier <monnier@iro.umontreal.ca>
Date: Tue, 30 Sep 2014 00:48:31 +0000 (-0400)
Subject: * lisp/minibuffer.el (completion-at-point): Emit warning for ill-behaved
X-Git-Tag: emacs-25.0.90~2635^2~679^2~194
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=a19f0977a96ee74b96410b41a8ea793c86f64b58;p=emacs.git

* lisp/minibuffer.el (completion-at-point): Emit warning for ill-behaved
completion functions.
---

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 003018d88d7..31e4e9d10f8 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,8 @@
+2014-09-30  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+	* minibuffer.el (completion-at-point): Emit warning for ill-behaved
+	completion functions.
+
 2014-09-29  Stefan Monnier  <monnier@iro.umontreal.ca>
 
 	* ses.el (ses--letref): Quote value before it gets re-evaluated.
diff --git a/lisp/minibuffer.el b/lisp/minibuffer.el
index f998843cd85..fb74af2e0df 100644
--- a/lisp/minibuffer.el
+++ b/lisp/minibuffer.el
@@ -2106,7 +2106,11 @@ The completion method is determined by `completion-at-point-functions'."
          (completion-in-region start end collection
                                (plist-get plist :predicate))))
       ;; Maybe completion already happened and the function returned t.
-      (_ (cdr res)))))
+      (_
+       (when (cdr res)
+         (message "Warning: %S failed to return valid completion data!"
+                  (car res)))
+       (cdr res)))))
 
 (defun completion-help-at-point ()
   "Display the completions on the text around point.