Hello boost, I'm trying to move some large code base to use boost 1.54. In some dark corner of it, the following was compiling fine: class Instance; typedef boost::setS OutEdgeList; typedef boost::listS VertexList; struct InstancePropertyTag { typedef boost::vertex_property_tag kind; }; typedef boost::property<InstancePropertyTag, Instance*> InstanceProperty; typedef boost::adjacency_list<OutEdgeList, VertexList, boost::bidirectionalS, InstanceProperty> Graph; typedef boost::property_map<Graph, boost::vertex_index_t>::type IndexGraph; under 1.54, I get 'attempt to form reference to void', but everything was fine under 1.46. I traced it a bit through template expansion, and the problem seems to be that the type for vertex_index_t is not found. The following declaration for InstanceProperty fixes (or hides) the problem: typedef boost::property<InstancePropertyTag, Instance*, boost::property<boost::vertex_index_t, int> > InstanceProperty; Does somebody know if some properties were added by default to graphs before and need to be explicitly added now? I don't find anything in the documentation and all examples I've found seem to imply that one wouldn't need to explicitly add a property declaration of vertex_index_t. Thanks a lot, Maurizio