Hi, In unordered/detail/table.hpp:177 the following exists: iterator& operator++() { node_ = node_ = static_cast(node_->next_); return *this; } iterator operator++(int) { iterator tmp(node_); node_ = node_ = static_cast(node_->next_); return tmp; } gcc 4.6.1 complains about boost_1_48_0/include/boost/unordered/detail/table.hpp:177:13: warning: operation on ‘this->boost::unordered::iterator_detail::iterator >*, std::pair >::node_’ may be undefined [-Wsequence-point] what is the purpose of node_ = node_ ?