mongocxx::result::insert_many::inserted_ids() does not modify the object, is thread-safe, and does not affect the results of future methods calls, so it should be const. This is similar to result::bulk_write::upserted_ids(), which is already const.

Original description:

Check all member functions for whether they can or should be made noexcept, or constexpr, or even just const.

Subsequent previous description:

Check all member functions for whether they can or should be made const.