error[E0605]: non-primitive cast: `Kind2` as `u8` --> $DIR/issue-88621.rs:9:13 | LL | let _ = Kind2::Foo() as u8; | ^^^^^^^^^^^^^^^^^^ an `as` expression can only be used to convert between primitive types or to coerce to a specific trait object error: aborting due to previous error For more information about this error, try `rustc --explain E0605`.