Sized, DynSized, and Unsized

from blog baby steps, | ↗ original
Extern types have been blocked for an unreasonably long time on a fairly narrow, specialized question: Rust today divides all types into two categories — sized, whose size can be statically computed, and unsized, whose size can only be computed at runtime. But for external types what we really want is a third category, types whose size can never...