Hello, I have this error w msvc2008: error C2664: 'nicohich::systems::make_parameters_for_simulate::type::type(c onst boost::fusion::vector1<T0> &)' : cannot convert parameter 1 from 'const parameters_1_n_seq_t' to 'const boost::fusion::vector1<T0> &' 1> with 1> [ 1> parameters_t=my_ns::systems::ns1::parameters, 1> T0=boost::variant 1> ] 1> and 1> [ 1> T0=boost::variant 1> ] 1> Reason: cannot convert from 'const parameters_1_n_seq_t' to 'const boost::fusion::vector1<T0>' 1> with 1> [ 1> T0=boost::variant 1> ] 1> No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called where parameters_1_n_seq_t which is a result of a metafunction invocation is: (as determined at runtime by typeid(parameters_1_n_seq_t).name(), I manually edited out the namespaces and trailing boost templates args ): fusion::transform_view< fusion::vector1< optional< variant< std::vector<double>, my_ns::range_incr<double>, my_ns::range<double>, double > >

, deoptionalize_item, void_

where struct deoptionalize_item { typedef deoptionalize_item Self; template<typename Sign> struct result; // primary template template<typename T> // template spec struct result { typedef const T& type; }; template <typename T> const T& operator()( const boost::optional<T>& rhs ) const { return *rhs; } }; my_ns::systems::ns1::parameters is defined as: namespace systems { struct base_parameters { double x; }; namespace ns1 { struct parameters : public base_parameters { // double y }; } } // at global namespace BOOST_FUSION_ADAPT_STRUCT( my_ns::systems::ns1::parameters, (double, x) // (double, y) ) Previously, parameters held the field y, and this error didn't happen. Regards,