The span of `function is never used` seem wrong

[pmarcelll]

Sample code:

fn foo() { println!("foo"); }

fn bar() {
    println!("bar");
}

fn main() {

}

Output:

warning: function is never used: `foo`, #[warn(dead_code)] on by default
 --> <anon>:1:1
  |
1 | fn foo() { println!("foo"); }
  | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: function is never used: `bar`, #[warn(dead_code)] on by default
 --> <anon>:3:1
  |
3 | fn bar() {
  | ^

If the function is only one row, the whole function can be highlighted, but if the funcion consists of multiple lines, only the first character (the f from fn) is highlighted.

[nagisa]

Duplicate of #33961