id summary reporter owner description type status milestone component version severity resolution keywords cc 10646 polygon::iterator_compact_to_points returns wrong equality for the (last & penultimate) iterators Vadim Sukhorukov Andrii Sydorchuk "''iterator_compact_to_points'' is the part of ''polygon_90'' concept. ''polygon_90_data'' class exposes 2 iterators: ''compact_iterator_type'' and ''iterator_type''. ''iterator_type'' extracts the complete point on-the-fly. And for the penultimate iterator it makes the wromg comparison with the last iterator. The reason of this bug is the specific implementation of operator++(). This is the same in boost versions 1.49 .. 1.56. At the moment I can propose the following workaround: {{{ typedef gtl::polygon_90_data Polygon90; typedef gtl::polygon_traits_90::point_type Point; typedef Polygon90::iterator_type Polygon90Iterator; bool equalIterators(const Polygon90Iterator& left, const Polygon90Iterator& right) { if (left == right) { return ((*left) == (*right)); } else { return false; } } }}} The implementation of operator++() [taken from boost sources]: {{{ inline iterator_compact_to_points& operator++() { iterator_type prev_iter = iter_; ++iter_; if(iter_ == iter_end_) { if(x(pt_) != firstX_) { iter_ = prev_iter; // this line produces the issue x(pt_, firstX_); } // it changes the cached point, but rolls back the iterator } else { set(pt_, orient_, *iter_); orient_.turn_90(); } return *this; } }}} The testing code: {{{ #include namespace gtl = boost::polygon; #include typedef gtl::polygon_90_data Polygon90; typedef gtl::polygon_traits_90::point_type Point; typedef Polygon90::iterator_type Polygon90Iterator; std::vector polygonData; polygonData.push_back(Point(15, 07)); // 1 polygonData.push_back(Point(20, 07)); // 2 polygonData.push_back(Point(20, 05)); // 3 polygonData.push_back(Point(16, 05)); // 4 polygonData.push_back(Point(16, 01)); // 5 polygonData.push_back(Point(01, 01)); // 6 polygonData.push_back(Point(01, 06)); // 7 polygonData.push_back(Point(03, 06)); // 8 polygonData.push_back(Point(03, 10)); // 9 polygonData.push_back(Point(05, 10)); // 10 Polygon90 polygon90; polygon90.set(polygonData.begin(), polygonData.end()); Polygon90Iterator it = polygon90.begin(); for (int i = 0; i < 8; i++) { it++; } Polygon90Iterator it_9th = it; it++; // this one points to 10th element bool bug = (it == it_9th); }}}" Bugs closed To Be Determined polygon Boost 1.58.0 Problem fixed