ices/91803.rs: fixed with errors

[github-actions]

Issue: rust-lang/rust#91803

trait Foo<'a> {}

fn or<'a>(first: &'static dyn Foo<'a>) -> dyn Foo<'a> {
    return Box::new(panic!());
}

pub fn main() {}

=== stdout ===
=== stderr ===
warning: unreachable call
 --> /home/runner/work/glacier/glacier/ices/91803.rs:4:12
  |
4 |     return Box::new(panic!());
  |            ^^^^^^^^ -------- any code following this expression is unreachable
  |            |
  |            unreachable call
  |
  = note: `#[warn(unreachable_code)]` on by default

error[E0746]: return type cannot have an unboxed trait object
 --> /home/runner/work/glacier/glacier/ices/91803.rs:3:43
  |
3 | fn or<'a>(first: &'static dyn Foo<'a>) -> dyn Foo<'a> {
  |                                           ^^^^^^^^^^^ doesn't have a size known at compile-time
  |
  = note: for information on `impl Trait`, see <https://doc.rust-lang.org/book/ch10-02-traits.html#returning-types-that-implement-traits>
help: use `impl Foo<'a>` as the return type, as all return paths are of type `Box<_>`, which implements `Foo<'a>`
  |
3 | fn or<'a>(first: &'static dyn Foo<'a>) -> impl Foo<'a> {
  |                                           ~~~~~~~~~~~~

error: aborting due to previous error; 1 warning emitted

For more information about this error, try `rustc --explain E0746`.
==============