- Move the type parameter from `encode` and `decode` methods to
the trait.
- Remove `UseSpecialized(En|De)codable` traits.
- Remove blanket impls for references.
- Add `RefDecodable` trait to allow deserializing to arena-allocated
references safely.
- Remove ability to (de)serialize HIR.
- Create proc-macros `(Ty)?(En|De)codable` to help implement these new
traits.
Return a pointer from `alloc_raw` instead of a slice. There is no
practical use for slice as a return type and changing it to a pointer
avoids forming references to an uninitialized memory.
Matthew Jasper
Tomasz Miąsko
Bastian Kauschke