For an IFR currency flight in a high-performance and/or complex airplane where the pilot flying has all the appropriate ratings and endorsements to be PIC, does another pilot with strictly a private ASEL certificate meet the legal requirements to be the safety pilot?

If so, I would assume the entire flight must be conducted in VMC. What other constraints or restrictions apply in such a scenario?

If permissible, how may the safety pilot log the flight so as to count toward future ratings and so on?