ices/68013.rs: fixed with errors

[github-actions]

Issue: rust-lang/rust#68013

// https://github.com/rust-lang/rust/issues/68013
// Reduced from [https://play.rust-lang.org/?version=nightly&mode=debug&edition=2018&gist=0f18f9d5d6071f9a10586e87e5dfd0b0]

#![feature(coerce_unsized)]

// These imports are also needed to get the ICE.
use std::rc::Rc;
use std::cell::Cell;
use std::ops::Deref;
use std::ops::CoerceUnsized;

#[derive(Clone)]
struct Redirectable<'a, T: ?Sized> {
    data: Rc<Cell<&'a T>>
}

impl<U, T: CoerceUnsized<U>> CoerceUnsized<Redirectable<'_, U>> for Redirectable<'_, T> {}

=== stdout ===
=== stderr ===
warning: unused import: `std::ops::Deref`
 --> /home/runner/work/glacier/glacier/ices/68013.rs:9:5
  |
9 | use std::ops::Deref;
  |     ^^^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

error[E0601]: `main` function not found in crate `68013`
  --> /home/runner/work/glacier/glacier/ices/68013.rs:4:1
   |
4  | / #![feature(coerce_unsized)]
5  | |
6  | | // These imports are also needed to get the ICE.
7  | | use std::rc::Rc;
...  |
16 | |
17 | | impl<U, T: CoerceUnsized<U>> CoerceUnsized<Redirectable<'_, U>> for Redirectable<'_, T> {}
   | |__________________________________________________________________________________________^ consider adding a `main` function to `/home/runner/work/glacier/glacier/ices/68013.rs`

error[E0277]: the trait bound `&T: std::marker::Unsize<&U>` is not satisfied
  --> /home/runner/work/glacier/glacier/ices/68013.rs:17:1
   |
17 | impl<U, T: CoerceUnsized<U>> CoerceUnsized<Redirectable<'_, U>> for Redirectable<'_, T> {}
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::marker::Unsize<&U>` is not implemented for `&T`
   |
   = note: all implementations of `Unsize` are provided automatically by the compiler, see <https://doc.rust-lang.org/stable/std/marker/trait.Unsize.html> for more information
   = note: required because of the requirements on the impl of `std::ops::CoerceUnsized<std::rc::Rc<std::cell::Cell<&U>>>` for `std::rc::Rc<std::cell::Cell<&T>>`

error: aborting due to 2 previous errors; 1 warning emitted

Some errors have detailed explanations: E0277, E0601.
For more information about an error, try `rustc --explain E0277`.
==============