It is currently not possible to wrap the view_updating_consumer in an std::optional. I intend to do it to allow for compactions to optionally generate view updates. The reason for that is that view_updating_consumer has a reference as a member, which makes the move assignment constructor not be implicitly generated. This patch fixes it by keeping a pointer instead of a reference. Signed-off-by: Glauber Costa <glauber@scylladb.com> Message-Id: <20200421123648.8328-1-glauber@scylladb.com>