error[E0596]: cannot borrow immutable local variable `x` as mutable
   --> $DIR/huge_multispan_highlight.rs:100:18
    |
12  |     let x = "foo";
    |         - consider changing this to `mut x`
...
100 |     let y = &mut x;
    |                  ^ cannot borrow mutably

error: aborting due to previous error(s)