Confusing error message with let _ : impl Trait;

[CDirkx]

A let binding with an existential type annotation and without an initializer expression results in error[E0720]: opaque type expands to a recursive type.

#![feature(impl_trait_in_bindings)]

fn foo() {
    let _ : impl Copy;
}

error[E0720]: opaque type expands to a recursive type
 --> src/lib.rs:4:13
  |
4 |     let _ : impl Copy;
  |             ^^^^^^^^^ expands to a recursive type
  |
  = note: type resolves to itself

(playground)

The mention of recursion here distracts from the actual problem (the type could not be resolved to/satisfied as a concrete type) and no hint is given how to fix this error.

Related: #66523