diff -r 4bb9e72e1a41 -r 7fdaa05a69a1 lemon/dfs.h
--- a/lemon/dfs.h	Wed Sep 12 17:25:48 2012 +0200
+++ b/lemon/dfs.h	Thu Sep 13 11:56:19 2012 +0200
@@ -1193,6 +1193,7 @@
         visitor.backtrack(arc);
       }
       _Visitor& visitor;
+      Constraints() {}
     };
   };
 #endif