Intra-doc links to items in `std::primitive` are broken

[ollie27]

For example [`std::primitive::i32`] generates a link to https://doc.rust-lang.org/nightly/std/primitive.std::primitive::i32.html.

[jyn514]

I didn't realize you could re-export primitives, good catch!

This will need a redesign of how rustdoc links primitives: right now it does pure text comparison, which will have to be changed to go through rustc_resolve. I think just looking at Res instead of is_primitive will work for almost everything, since you can't define a primitive and module in the same scope:

mod inner {
    pub use u64;
    //^~ ERROR ambiguous
    
    pub mod u64 {}
    //^~ ERROR defined multiple times
}

The only thing rustdoc needs to second-guess resolve on is for primitives and modules with the same name:

/// [prim@char]
/// [mod@char]
mod char {}

So this usage needs to stay:

rust/src/librustdoc/passes/collect_intra_doc_links.rs

Line 1138 in 5ea3eaf

if let Some((path, prim)) = is_primitive(path_str, TypeNS) {

but everything else should be removed and check Res::PrimTy instead.

[jyn514]

I expect fixing this to also fix #76693 at the same time.

[jyn514]

A related issue: when this is fixed, the link text displayed for primitives will be wrong:

rust/src/librustdoc/passes/collect_intra_doc_links.rs

Line 1058 in 8a13fc4

link_text: path_str.to_owned(),

That should just say link_text instead.