Hi, I've just got an error I would think impossible with variant: assigning another variant to it triggered the false assert at /usr/include/boost/variant/detail/visitation_impl.hpp:203 which, IIUC, seems to say that there is a lack of a fallback type... FWIW, it's a variant holding 3 types, an int and 2 pointers types. When the error occurs, it's in the copy constructor of an object holding such a variant, and at this moment, the rhs variant holds it's third type, the second pointer type. The exact error is, at runtime (compilation goes without a warning): /usr/include/boost/variant/detail/visitation_impl.hpp:203: typename Visitor::result_type boost::detail::variant::visitation_impl(int, int, Visitor&, VPCV, mpl_::true_, NBF, W*, S*) [with W = mpl_::int_<20>, S = boost::detail::variant::visitation_impl_stepboost::mpl::l_end, boost::mpl::l_iterboost::mpl::l_end >, Visitor = boost::variant::node_iterator*, twotypestree::tree::leaf_iterator*, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_>::assigner, VPCV = const void*, NBF = boost::variant::node_iterator*, twotypestree::tree::leaf_iterator*, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_, boost::detail::variant::void_>::has_fallback_type_]: Assertion `false' failed. - twotypestree::tree is a tree holding a different data at it's nodes (T1 here) and it's leafs (T2* here). - twotypestree::tree_placeholder is an enum with just a value, not_a_tree The code triggering the problem is as simple as: tree_iterator(const tree_iterator& original) { pimpl_ = original.pimpl_; // pimpl_ is the variant } Would anyone see what the problem is? Confusingly, Nowhere man -- nowhere.man@levallois.eu.org OpenPGP 0xD9D50D8A