Allow generic parameters in intra-doc links

[camelid]

Fixes #62834.

---

The contents of the generics will be mostly ignored (except for warning
if fully-qualified syntax is used, which is currently unsupported in
intra-doc links - see issue #74563).

• Allow links like Vec<T>, Result<T, E>, and Option<Box<T>>
• Allow links like Vec::<T>::new()
• Warn on
  • Unbalanced angle brackets (e.g. Vec<T or Vec<T>>)
  • Missing type to apply generics to (<T> or <Box<T>>)
  • Use of fully-qualified syntax (<Vec as IntoIterator>::into_iter)
  • Invalid path separator (Vec:<T>:new)
  • Too many angle brackets (Vec<<T>>)
  • Empty angle brackets (Vec<>)

Note that this implementation does allow some constructs that aren't
valid in the actual Rust syntax, for example Box::<T>new(). That may
not be supported in rustdoc in the future; it is an implementation
detail.

[rust-highfive]

Some changes occurred in intra-doc-links.

cc @jyn514

[rust-highfive]

r? @ollie27

(rust_highfive has picked a reviewer for you, use r? to override)

[jyn514]

r? @jyn514

[camelid]

I think all that's left to do is add some UI tests for the warning!

[camelid]

By the way, I would like to squash this a bit so the commit history is a bit nicer, so I would appreciate it if you could let me know before r+ing :)

[jyn514]

error: unresolved link to `<Self as Trait>::MyAType: Eq, <Self as Trait>::MyAType: PartialEq<<Self as Trait>::MyAType>`
   --> compiler/rustc_middle/src/ty/query/plumbing.rs:522:17
    |
522 |             $($(#[$attr])*  $name: QueryState<
    |                 ^^^^^^^^
    | 
   ::: compiler/rustc_middle/src/ty/query/mod.rs:105:1
    |
105 | rustc_query_append! { [define_queries!][<'tcx>] }
    | ------------------------------------------------- in this macro invocation
    |
    = note: `-D broken-intra-doc-links` implied by `-D warnings`
    = note: see https://github.com/rust-lang/rust/issues/74563 for more information
    = note: fully-qualified syntax is unsupported
    = note: this error originates in a macro (in Nightly builds, run with -Z macro-backtrace for more info)

Looks like some queries aren't quoting code properly. The span is unhelpful, you can find the query docs at https://github.com/rust-lang/rust/blob/master/compiler/rustc_middle/src/query/mod.rs. You can test locally with x.py doc --stage 1 compiler/rustc_middle; you may want --keep-stage 0 to avoid rebuilding rustc_middle after a doc change.

[camelid]

Hmm, do you mean https://github.com/rust-lang/rust/blob/master/compiler/rustc_middle/src/query/mod.rs or https://github.com/rust-lang/rust/blob/master/compiler/rustc_middle/src/ty/query/mod.rs?

[jyn514]

@bors r+

[bors]

📌 Commit e2424a2 has been approved by jyn514

[bors]

⌛ Testing commit e2424a2 with merge b1af43b...

[bors]

☀️ Test successful - checks-actions, checks-azure
Approved by: jyn514
Pushing b1af43b to master...