Hi, i'm new to boost and encountered the following problem with the boost graph library and this code: #include "boost/graph/adjacency_list.hpp" #include "boost/graph/adjacency_matrix.hpp" #include "boost/graph/filtered_graph.hpp" int main (void) { using namespace boost; typedef adjacency_matrix<undirectedS> Graph; //typedef adjacency_list<vecS, vecS, undirectedS> Graph; typedef filtered_graph<Graph, keep_all> FilteredGraph; Graph g (5); FilteredGraph fg (g, keep_all ()); } This results in a lot of error messages from the compiler (see end of email), all located in the bgl files. If i use adjacency_list (as in the commented line above) instead of adjacency_matrix, everything's fine. I use gcc 3.3 under linux and version 1.30 of the boost library. Is this a bug? Is there an easy way to make filtered_graph work with adjacency_matrix? (I'd like to use adjacency_matrix because my graphs are almost complete graphs). Best regards, Matthias Rupp The first error messages from the compiler (the rest are also complaints about forming references to void): ../boost_1_30_0/boost/iterator_adaptors.hpp: In instantiation of `boost::iterator_adaptor<void, boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void>, boost::detail::matrix_edge_desc_impl<boost::undirected_tag, size_t>, boost::detail::matrix_edge_desc_impl<boost::undirected_tag, size_t>, boost::detail::matrix_edge_desc_impl<boost::undirected_tag, size_t>*, boost::multi_pass_input_iterator_tag, ptrdiff_t>': ../boost_1_30_0/boost/graph/filtered_graph.hpp:216: instantiated from `boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all>' complaint.cpp:23: instantiated from here ../boost_1_30_0/boost/iterator_adaptors.hpp:852: error: forming reference to void ../boost_1_30_0/boost/iterator_adaptors.hpp:927: error: forming reference to void ../boost_1_30_0/boost/iterator_adaptors.hpp: In instantiation of `boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void>': ../boost_1_30_0/boost/type_traits/is_convertible.hpp:128: instantiated from `boost::detail::is_convertible_basic_impl<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void>&, boost::detail::int_convertible>' ../boost_1_30_0/boost/type_traits/is_convertible.hpp:191: instantiated from `boost::detail::is_convertible_impl<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void>&, boost::detail::int_convertible>' ../boost_1_30_0/boost/type_traits/is_enum.hpp:91: instantiated from `boost::is_convertible<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void>&, boost::detail::int_convertible>' ../boost_1_30_0/boost/type_traits/is_enum.hpp:91: instantiated from `boost::detail::is_enum_helper<false>::type<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void>&>' ../boost_1_30_0/boost/type_traits/is_enum.hpp:91: instantiated from `boost::detail::is_enum_impl<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void> >' ../boost_1_30_0/boost/type_traits/is_scalar.hpp:36: instantiated from `boost::is_enum<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void> >' ../boost_1_30_0/boost/type_traits/is_scalar.hpp:36: instantiated from `boost::detail::is_scalar_impl<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void> >' ../boost_1_30_0/boost/type_traits/is_class.hpp:76: instantiated from `boost::is_scalar<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void> >' ../boost_1_30_0/boost/type_traits/is_class.hpp:76: instantiated from `boost::detail::is_class_impl<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void> >' ../boost_1_30_0/boost/type_traits/is_empty.hpp:75: instantiated from `boost::is_class<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void> >' ../boost_1_30_0/boost/type_traits/is_empty.hpp:75: instantiated from `boost::detail::is_empty_impl<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void> >' ../boost_1_30_0/boost/iterator_adaptors.hpp:934: instantiated from `boost::is_empty<boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void> >' ../boost_1_30_0/boost/iterator_adaptors.hpp:934: instantiated from `boost::compressed_pair<void, boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void> >' ../boost_1_30_0/boost/iterator_adaptors.hpp:934: instantiated from `boost::iterator_adaptor<void, boost::filter_iterator_policies<boost::detail::in_edge_predicate<boost::keep_all, boost::keep_all, boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all> >, void>, boost::detail::matrix_edge_desc_impl<boost::undirected_tag, size_t>, boost::detail::matrix_edge_desc_impl<boost::undirected_tag, size_t>, boost::detail::matrix_edge_desc_impl<boost::undirected_tag, size_t>*, boost::multi_pass_input_iterator_tag, ptrdiff_t>' ../boost_1_30_0/boost/graph/filtered_graph.hpp:216: instantiated from `boost::filtered_graph<main()::Graph, boost::keep_all, boost::keep_all>' complaint.cpp:23: instantiated from here ../boost_1_30_0/boost/iterator_adaptors.hpp:1313: error: forming reference to void ../boost_1_30_0/boost/iterator_adaptors.hpp:1315: error: forming reference to void ../boost_1_30_0/boost/iterator_adaptors.hpp:1344: error: forming reference to void 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