In RFC #803 I am proposing some tweaks to the coercion rules which were proposed and accepted in RFC #401. In particular I would like to bring people’s attention to the fact that implicit coercions will not be changed to being valid explicit casts. I.e., if you can write let _: T = foo; you will not be able to write foo as T. This is pretty close to the current situation, so it shouldn’t affect very much code (I believe coercion from a reference-to-concrete-type to trait-object is the only currently allowed instance), but it was a popular part of RFC 401, so I wanted to draw people’s attention to the change.
The change is described in this comment.