proc macro (derive) does not recognized as ambiguous intra doc link

[pickfire]

I tried this code:

/// [`Dummy`] should be ambiguous. But it works.
pub trait Dummy<T>: Sized {
}

#[cfg(feature = "derive")]
pub use dummy::Dummy; // this is a derive macro

Try doing that on https://github.com/cksac/fake-rs crate or serde

I expected to see this happen: ambiguous Dummy link found, use explicit macro@Dummy.

Instead, this happened: It compiles

[jyn514]

This is intentional:

rust/src/librustdoc/passes/collect_intra_doc_links.rs

Line 808 in 6b56603

fn is_derive_trait_collision<T>(ns: &PerNS<Result<(Res, T), ResolutionFailure<'_>>>) -> bool {

. Otherwise every time you link to Copy or Debug you'd get an ambiguity error.

[pickfire]

Otherwise every time you link to Copy or Debug you'd get an ambiguity error.

But what about other crates? It would be weird that users does not know about that? Should we make Copy and Debug special case that we can ignore for warning? Otherwise users can easily link to the wrong link if they didn't check the generated doc. Or maybe we should just warn after all.

[jyn514]

This was documented in #110328. I'm going to close this since we're not planning to change the behavior.