rustdoc: `broken_intra_doc_links` is incorrectly reported when linking to a proc macro

[camelid]

Rustdoc only emits a documentation page for my_macro as a macro; there's no function page for it.

Note that the link indeed fails to resolve.

Code

//! Link to [`my_macro`].

#![crate_type = "proc-macro"]

extern crate proc_macro;

#[proc_macro]
pub fn my_macro(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
    input
}

Output

warning: `my_macro` is both a function and a macro
 --> foo.rs:1:15
  |
1 | //! Link to [`my_macro`].
  |               ^^^^^^^^ ambiguous link
  |
  = note: `#[warn(rustdoc::broken_intra_doc_links)]` on by default
help: to link to the function, add parentheses
  |
1 | //! Link to [`my_macro()`].
  |                       ++
help: to link to the macro, add an exclamation mark
  |
1 | //! Link to [`my_macro!`].
  |                       +

warning: 1 warning emitted

[camelid]

Adding the ! as suggested causes the link to resolve successfully.

However, I found another, related bug: When I add (), the link resolves successfully—to the macro!

[jyn514]

Hmm, I don't think my_macro() resolving is actually a bug? It is a function, it just happens to also be a macro.

I agree that the warning isn't helpful though since the link is the same in both cases.