For instance, fixing http://hub.qgis.org/issues/12010 requires knowledge that the Postgres datasource contains z values, and the inserted geometry should also have these. Without breaking API and making QgsVectorDataProvider::geometryType() return a QgsWKBTypes::Type (or adding another signature geometryTypeV2() ) this is not currently possible.
A rough estimate is that Qgis::WkbType is used around 1000 times through the codebase, it is unknown at this stage how many occurrences could be just ported in place without additional work.
Currently two different enums are used in QGIS for storing WKB types - the older QGis::WkbType and the replacement QgsWKBTypes::Type enum.
Aside from making things difficult to work with (Eg https://github.com/qgis/QGIS/blob/master/src/core/qgsvectorfilewriter.cpp#L1729 ), it also makes it difficult to fully support z/m values throughout QGIS.
For instance, fixing http://hub.qgis.org/issues/12010 requires knowledge that the Postgres datasource contains z values, and the inserted geometry should also have these. Without breaking API and making QgsVectorDataProvider::geometryType() return a QgsWKBTypes::Type (or adding another signature geometryTypeV2() ) this is not currently possible.
A rough estimate is that Qgis::WkbType is used around 1000 times through the codebase, it is unknown at this stage how many occurrences could be just ported in place without additional work.