Impl trait in let bindings

You can also use impl Trait in the type of a local variable:

#![allow(unused)]
fn main() {
let x: impl Clone = 22_i32;
}

This is equivalent to introducing a type alias impl trait with the scope of the enclosing function:

#![allow(unused)]
fn main() {
type X = impl Clone;
let x: X = 22_i32;
}