Help message in E0369 points to wrong file

[ElectrifyPro]

I have the following code, split into two files:

// src/main.rs
// this appears in the error

mod name;

use name::Name;

fn main() {
    let name_1 = Name::from("John Cena");
    let name_2 = Name::from("Not John Cena");
    println!("{}", name_1 == name_2);
}

// src/name.rs
pub struct Name {
    pub first: String,
    pub middle: String,
    pub last: String,
}

impl From<&str> for Name {
    fn from(name: &str) -> Self {
        let mut parts = name.split_whitespace();
        let first = parts.next().unwrap_or_default();
        let last = parts.clone().last().unwrap_or_default();
        let middle = parts.collect::<Vec<_>>().join(" ");
        Self {
            first: first.to_owned(),
            middle,
            last: last.to_owned(),
        }
    }
}

This code, as expected, produces E0369, shown below. However, the help message at the bottom of the error appears to be referencing line 2 in src/main.rs, while displaying the filename src/name.rs, thus suggesting we add the derive annotation to a comment in src/main.rs. It should instead point to the struct in src/name.rs.

error[E0369]: binary operation `==` cannot be applied to type `Name`
  --> src/main.rs:11:27
   |
11 |     println!("{}", name_1 == name_2);
   |                    ------ ^^ ------ Name
   |                    |
   |                    Name
   |
note: an implementation of `PartialEq` might be missing for `Name`
  --> src/name.rs:2:1
   |
2  | pub struct Name {
   | ^^^^^^^^^^^^^^^ must implement `PartialEq`
help: consider annotating `Name` with `#[derive(PartialEq)]`
  --> src/name.rs:2:1
   |
2  + #[derive(PartialEq)]
3  | // this appears in the error
   |

Meta

rustc --version --verbose:

rustc 1.73.0-nightly (903e279f4 2023-07-18)
binary: rustc
commit-hash: 903e279f468590fa3425f8aff7f3d61a5a873dbb
commit-date: 2023-07-18
host: x86_64-unknown-linux-gnu
release: 1.73.0-nightly
LLVM version: 16.0.5

[clubby789]

@rustbot claim

[clubby789]

The issue is that in

rust/compiler/rustc_errors/src/emitter.rs

Lines 1984 to 1987 in 39f42ad

	let file_lines = sm
	.span_to_lines(span.primary_span().unwrap().shrink_to_hi())
	.expect("span_to_lines failed when emitting suggestion");
	let line_num = sm.lookup_char_pos(parts[0].span.lo()).line;

, the span we use to look up the file/line mapper is the primary span of the message, i.e. the error in main.rs