1 error[E0720]: cannot resolve opaque type
2 --> $DIR/binding-without-value.rs:5:13
4 LL | let _ : impl Copy;
5 | - ^^^^^^^^^ cannot resolve opaque type
7 | this binding might not have a concrete type
9 help: set the binding to a value for a concrete type to be resolved
11 LL | let _ : impl Copy = /* value */;
14 error: aborting due to previous error
16 For more information about this error, try `rustc --explain E0720`.