diff -r 0976225b5cae -r be7dd3a8d6a3 lemon/dfs.h
--- a/lemon/dfs.h	Wed Jan 11 14:01:21 2012 +0100
+++ b/lemon/dfs.h	Fri Jan 20 19:20:02 2012 +0100
@@ -1193,6 +1193,7 @@
         visitor.backtrack(arc);
       }
       _Visitor& visitor;
+      Constraints() {}
     };
   };
 #endif