Looks like gcc is not smart enough to guess to call `operator std::vector<int>()`
..\example\ddd.cpp:12: error: call of overloaded 'vector(boost::assign_detail::generic_list<int>&)' is ambiguous
... stl_vector.h:241: note: candidates are: std::vector<_Tp, _Alloc>::vector(const std::vector<_Tp, _Alloc>&) [with _Tp = int, _Alloc = std::allocator<int>]
... stl_vector.h:227: note: std::vector<_Tp, _Alloc>::vector(size_t, const _Tp&, const _Alloc&) [with _Tp = int, _Alloc = std::allocator<int>]
... stl_vector.h:215: note: std::vector<_Tp, _Alloc>::vector(const _Alloc&) [with _Tp = int, _Alloc = std::allocator<int>]
Regards, Andrey