Resolve intra-doc links on additional documentation for re-exports in lexical scope

[jyn514]

Fixes #77254.

• Preserve the parent module of DocFragments

  • Add parent_module to DocFragment

  • Require the parent_module of the item being inlined

  • Preserve the hir_id for ExternCrates so rustdoc can find the parent module later

  • Take an optional parent_module for build_impl and merge_attrs.
    Preserve the difference between parent modules for each doc-comment.

  • Support a single additional re-exports in from_ast. Originally this took a vec but I ended up not using it.

  • Don't require the parent_module for all impls, just inlined items

    In particular, this will be None whenever the attribute is not on a
    re-export.

  • Only store the parent_module, not the HirId

    When re-exporting a re-export, the HirId is not available. Fortunately,
    collect_intra_doc_links doesn't actually need all the info from a
    HirId, just the parent module.

• Introduce Divider

  This distinguishes between documentation on the original from docs on the re-export.

• Use the new module information for intra-doc links

  • Make the parent module conditional on whether the docs are on a re-export

  • Make resolve_link take &Item instead of &mut Item

    Previously the borrow checker gave an error about multiple mutable
    borrows, because dox borrowed from item.

  • Fix crate:: for re-exports

    crate means something different depending on where the attribute
    came from.

  • Make it work for #[doc] attributes too

    This required combining several attributes as one so they would keep
    the links.

r? @GuillaumeGomez

[jyn514]

run collapse docs on one module at a time.

One suggestion @Nemo157 had was to add a new DocFragmentKind::Divider which distinguishes between doc-comments on the original item and the comments on the export. Then collapse_docs wouldn't need to change at all, since it already distinguishes between attributes of different kinds.

[jyn514]

add a new DocFragmentKind::Divider

This seems to have worked pretty well.

[jyn514]

It works! Just need to add test cases.

[jyn514]

The FIXME by the new behavior in intra-doc links will break a lot of code in practice, see e.g. https://docs.rs/async-compression/0.3.5/src/async_compression/lib.rs.html#1-240. Another alternative is to combine all consecutive attributes with the same module id into the same markdown link.

I don't plan to support that sort of inter-dependence across re-exports, though.

[jyn514]

This is ready for review.

[GuillaumeGomez]

Thanks!

@bors: r+

[bors]

📌 Commit e39a860 has been approved by GuillaumeGomez

[bors]

⌛ Testing commit e39a860 with merge 9ba1d21...

[bors]

☀️ Test successful - checks-actions, checks-azure
Approved by: GuillaumeGomez
Pushing 9ba1d21 to master...

[dylni]

Thanks! This is working well except for #77783.