> After this change (and on the 2024 edition), the compiler assumes that T should be !, which doesn't implement Default, and therefore causes a compilation error.
If ! can coerce to every type, why not treat it as if it implemented every trait too?
The never type seems very useful in various languages to either signal that a branch can never happen (the example of string -> bytestring never erroring) or to mark that a function will never return a value (and thus control) to the caller.
A simple TypeScript example:
const forever = (): never => { while (true) { // whatever } }
The Default trait provides a function that actually constructs the type in question. But here the ! type can never be constructed, so the only way to implement Default would be to have it panic, loop infinitely, or otherwise fail at runtime.
So this would risk turning a compile-time error into a runtime error.
Moreover, Rust traits' associated constants/types get in the way of having a proper bottom type. What would <! as Iterator>::Item be? (In Scala I think it just doesn't compile?)
Ah, that makes sense. Rust noob here, so I wasn't aware traits can act on types directly without any instance of the type. Thanks for the info!