Reading a `&T` as a `T` — the open half of 18.25

Decided

D-0035, settled by the language’s author: part of spec §18. Older text cites it as 18.35.

Implicit, for a copyable T. A reference is accepted where its referent’s type is wanted, and the value is copied: for m in list.iter() { if m.name == name { return m } } returns a Movie. Reading cannot fail, so by the rule that makes ^T → &T loud and &mut T → ^T quiet, it is not spelled. A move-only T is still refused, as a move out of a borrow; a generic body needs T: Copy. An explicit r^ was considered and rejected — it would put a sigil on the most ordinary read in the language — and ^ stays the pointer dereference (§5.2)