ices/99777-2.rs: fixed with errors

[github-actions]

Issue: rust-lang/rust#99777

pub fn test() {
    #[doc(alias = "test")]
    let num_flags = 0;
}

=== stdout ===
=== stderr ===
warning: unused doc comment
 --> /home/runner/work/glacier/glacier/ices/99777-2.rs:2:5
  |
2 |     #[doc(alias = "test")]
  |     ^^^^^^^^^^^^^^^^^^^^^^
3 |     let num_flags = 0;
  |     ------------------ rustdoc does not generate documentation for statements
  |
  = note: `#[warn(unused_doc_comments)]` on by default
  = help: use `//` for a plain comment

error[E0601]: `main` function not found in crate `99777_2`
 --> /home/runner/work/glacier/glacier/ices/99777-2.rs:4:2
  |
4 | }
  |  ^ consider adding a `main` function to `/home/runner/work/glacier/glacier/ices/99777-2.rs`

error: `#[doc(alias = "...")]` isn't allowed on statement
 --> /home/runner/work/glacier/glacier/ices/99777-2.rs:2:11
  |
2 |     #[doc(alias = "test")]
  |           ^^^^^^^^^^^^^^

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

For more information about this error, try `rustc --explain E0601`.
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