diff -r ee581a0ecfbf -r b873350e6258 lemon/dfs.h
--- a/lemon/dfs.h	Fri Jan 06 16:27:06 2012 +0100
+++ b/lemon/dfs.h	Thu Jan 19 15:25:06 2012 +0100
@@ -1191,6 +1191,7 @@
         visitor.backtrack(arc);
       }
       _Visitor& visitor;
+      Constraints() {}
     };
   };
 #endif