I don't have time for a full write-up of this right now, so I'm just opening an issue so I have somewhere to point people when they open rustdoc issues.

Motivation:

• search items are duplicated (rustdoc: do something about reexported items rust#15723)
• rustdoc sometimes links to the original definition, even for facade crates that use inlining: Rustdoc links to std library types can bypass the facade rust#22083
  • ditto, but for intra-doc links: Rustdoc links items in the standard library to the original crate, not the re-export rust#78467 (deemed to be a duplicate of the issue above)
• rustdoc sometimes links to a re-export, even when it is named differently than the link the user wrote: rustdoc: Incorrect link to item when the item is reexported and inlined rust#83976

doc(canonical) could tell rustdoc the 'one true path' the item should appear at.

Possible difficulties:

• doc(canonical) is necessarily unique across all crates. rustdoc should give an error if it's duplicated.
• rustdoc currently stores search-index.json per-crate. This will need a redesign if rustdoc only know to hide the item after the documentation has been generated and it goes onto the next crate

Unresolved questions:

• Does inlining still make sense with doc(canonical)? Should all other usages just link to the canonical crate? How does this work if the canonical usage is in a reverse-dependency?

cc @camelid