[boost] Graph library concept check problem

From: Matthias Troyer (troyer_at_[hidden])
Date: 2006-04-28 00:36:44

Hi,

Trying to compile our ALPS project sources (http://alps.comp- 
phys.org) with the CVS HEAD I encountered a number of problems with  
the BGL concept checking. In particular on MacOS X, using the Apple g+ 
+ 4.0.1, I encounter problems in depth_first_search.hpp with:

   template <class Visitor, class Graph>
   class DFSVisitorConcept {
   public:
     void constraints() {
       function_requires< CopyConstructibleConcept<Visitor> >();
       vis.initialize_vertex(u, g);
       vis.start_vertex(u, g);
       vis.discover_vertex(u, g);
       vis.examine_edge(e, g);
       vis.tree_edge(e, g);
       vis.back_edge(e, g);
       vis.forward_or_cross_edge(e, g);
       vis.finish_vertex(u, g);
     }
   private:
     Visitor vis;
     Graph g;
     typename graph_traits<Graph>::vertex_descriptor u;
     typename graph_traits<Graph>::edge_descriptor e;
   };

Somehow this tries to instantiate a default constructor for the  
visitor and the graph. Since some graph types do not have a default  
constructor and no default constructor should actually be required, I  
want to ask whether this is a bug in the compiler or in the concept  
checks?

Matthias