Version 0.4.11 of rental is published, fixing a few bugs when trait objects are used inside a rental struct.
Until now, using a trait object as a prefix field would result in a type error. The cause was a missing deref, that for most other types would be automatically coerced into the proper type. Adding an explicit deref fixes the issue.
Additionally, trait objects with lifetime bounds could result in unparseable output. The fix for this was encapsulating the type in parens when it's the target of a ref.