error[E0605]: non-primitive cast: `E` as `isize`
  --> $DIR/uninhabited-enum-cast.rs:4:20
   |
LL |     println!("{}", (e as isize).to_string());
   |                    ^^^^^^^^^^^^
   |
   = note: an `as` expression can only be used to convert between primitive types. Consider using the `From` trait

error: aborting due to previous error

For more information about this error, try `rustc --explain E0605`.