rustdoc: Show span of link definition for `broken_intra_doc_links`

[camelid]

Code

//! Look at [foo].
//!
//! [foo]: Nonexistent

Error

warning: unresolved link to `Nonexistent`
 --> foo.rs:1:13
  |
1 | //! Look at [foo].
  |             ^^^^^ no item named `Nonexistent` in scope
  |
  = note: `#[warn(broken_intra_doc_links)]` on by default
  = help: to escape `[` and `]` characters, add '\' before them like `\[` or `\]`

Instead (or in addition) it should point to [foo]: Nonexistent. The way it is now is confusing because you can't see Nonexistent anywhere in the span that is pointed to.

Not sure if an issue for this already exists, so I filed this one.

[jyn514]

Oh ugh, #80550 never got backported. This is fixed on beta.

[jyn514]

Personally I don't think this is worth a stable-backport.

[jyn514]

This is fixed in 1.51.0.