Use liballoc's specialised in-place vec collection liballoc already specialises in-place vector collection, so manually reimplementing it in `IdFunctor::try_map_id` was superfluous.
RefCell
TransitiveRelation
lazy::Sync{OnceCell,Lazy}
sync::{Once,Lazy}Lock
rustc_data_structures::thin_vec::ThinVec
thin_vec::ThinVec
Encodable
Encoder