IndexSet is allowed to provide its GeometryTypes list as something else than std::vector<GeometryType>. Therefore the IndexSet::Types alias is available. Most grids just return a std::vector, but, e.g., AlbertaGrid returns a std::array instead. Almost all grids could returns something cheaper than std::vector since there is only a single GeometryType. This MR, fixes the handling of this flexibility in the ParallelGrid wrapper by copying the GeometryTypes into the new storage.
