There has been a major overhaul of the geometry classes in QGIS. The old classes have been renamed (as per the table below). New geometry classes will properly preserve Z and M attributes if present.
References https://github.com/qgis/qgis3.0_api/issues/11
This finally brings back a consistent state in naming within the geometry API
| QGIS 2 | QGIS 3 | |--------------------|--------------------| | QgsPolygon | QgsPolygonXY | | QgsMultiPoint | QgsMultiPointXY | | QgsMultiPolyline | QgsMultiPolylineXY | | QgsMultiPolygon | QgsMultiPolygonXY | | QgsPolygonV2 | QgsPolygon | | QgsMultiPointV2 | QgsMultiPoint | | QgsMultiPolylineV2 | QgsMultiPolyline | | QgsMultiPolygonV2 | QgsMultiPolygon |
See also https://github.com/qgis/QGIS/pull/5491
This feature was developed by Matthias, Nyall and others