Hello all, I have a problem here which boils down to the non-constness of iterator_traits for const_iterator of flat_map: void Foo() { typedef boost::container::flat_map Int2IntFmap; Int2IntFmap::const_iterator it2; std::iterator_traitsInt2IntFmap::const_iterator::value_type::first_type& r2 = it2->first; } 1>d:\develop\shared\main\test\testcommon\testgeneral\nctstgenhmhandlemap.cpp(59): error C2440: 'initializing' : cannot convert from 'const int' to 'int &' Anyone an idea or should I use decltype instead?