X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fpcl%2Fdefcombin.lisp;h=060f4a0cd0b907bd5839f41752bec352bd09c7c4;hb=b86f43bae31f775d834c724e21f0f573b968f695;hp=8b71ed426466df57aa79c8ace02ddf7758c99bb5;hpb=1ae37c6f729950b6925275cea43546b701d8fde2;p=sbcl.git

diff --git a/src/pcl/defcombin.lisp b/src/pcl/defcombin.lisp
index 8b71ed4..060f4a0 100644
--- a/src/pcl/defcombin.lisp
+++ b/src/pcl/defcombin.lisp
@@ -25,10 +25,13 @@
 
 (defmacro define-method-combination (&whole form &rest args)
   (declare (ignore args))
-  (if (and (cddr form)
-	   (listp (caddr form)))
-      (expand-long-defcombin form)
-      (expand-short-defcombin form)))
+  `(progn
+     (with-single-package-locked-error
+	 (:symbol ',(second form) "defining ~A as a method combination"))
+     ,(if (and (cddr form)
+	       (listp (caddr form)))
+	  (expand-long-defcombin form)
+	  (expand-short-defcombin form))))
 
 ;;;; standard method combination