rustdoc-search: search for references

[notriddle]

This feature extends rustdoc with syntax and search index information for searching borrow references. Part of #60485

Preview

• &mut
• &Option<T> -> Option<&T>
• &mut Option<T> -> Option<&mut T>

Updated chapter of the book: https://notriddle.com/rustdoc-html-demo-11/reference/rustdoc/read-documentation/search.html

Motivation

See #119676

Guide-level explanation

You can't search by lifetimes, but other than that it's the same syntax references normally use.

Reference-level description

Shorthand	Explicit names
Before this PR
[]	primitive:slice and/or primitive:array
[T]	primitive:slice<T> and/or primitive:array<T>
!	primitive:never
()	primitive:unit and/or primitive:tuple
(T)	T
(T,)	primitive:tuple<T>
(T, U -> V, W)	fn(T, U) -> (V, W), Fn, FnMut, and FnOnce
New additions with this PR
&	primitive:reference
&mut	primitive:reference<keyword:mut>
&T	primitive:reference<T>
&mut T	primitive:reference<keyword:mut, T>

Search query grammar

borrow-ref = AMP *WS [MUT] *WS [arg]

arg = [type-filter *WS COLON *WS] (path [generics] / slice-like / tuple-like / borrow-ref)

AMP = "&"
MUT = "mut"

Future direction

As described in #118194 and #119676

• The remaining type expression grammar (this is another step in the type expression grammar: ReferenceType is now supported)
• Search subtyping and traits

[rustbot]

r? @GuillaumeGomez

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[rustbot]

Some changes occurred in HTML/CSS/JS.

cc @GuillaumeGomez, @jsha

[GuillaumeGomez]

Looks good to me, thanks! Since it extends the search capabilities, let's start an FCP.

@rfcbot fcp merge

[rfcbot]

Team member @GuillaumeGomez has proposed to merge this. The next step is review by the rest of the tagged team members:

• @GuillaumeGomez
• @Manishearth
• @Nemo157
• @aDotInTheVoid
• @camelid
• @jsha
• @notriddle

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

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[rfcbot]

🔔 This is now entering its final comment period, as per the review above. 🔔