[Boost-users] boost::variant and SGI's compose1 cause constness error

Hi there, I have a problem using boost::variant. I want apply_visitor to go through a list of pairs whose first type is a variant. Using compose1 and select1st from the SGI extensions to the STL yields a constness error. The problem is illustrated by the attached code which shoud be compiled with the g++ (the SGI extensions are here available via __gnu_cxx). What's wrong? Is it my fault using the library or is it a missing const version in apply_visitor_delayed_t()? Thanks a lot for any hints! Best, Erwin