As our implementation of MCP411 nears completion and we begin to
solicit testing, it's no longer reasonable to expect testers to
type or remember `BikeshedIntrinsicFrom`. The name degrades the
ease-of-reading of documentation, and the overall experience of
using compiler safe transmute.
Tentatively, we'll instead adopt `TransmuteFrom`.
This name seems to be the one most likely to be stabilized, after
discussion on Zulip [1]. We may want to revisit the ordering of
`Src` and `Dst` before stabilization, at which point we'd likely
consider `TransmuteInto` or `Transmute`.
[1] https://rust-lang.zulipchat.com/#narrow/stream/216762-project-safe-transmute/topic/What.20should.20.60BikeshedIntrinsicFrom.60.20be.20named.3F
- Create `Answer` type that is not just a type alias of `Result`
- Remove a usage of `map_layouts` to make the code easier to read
- Don't hide errors related to Unknown Layout when computing transmutability
