Auto merge of #111958 - notriddle:notriddle/type-search-slice-array, r=GuillaumeGomez
rustdoc: search for slices and arrays by type with `[]`
This feature extends rustdoc to support the syntax that most users will naturally attempt to use to search for slices and arrays. Part of #60485
Function signature searches already support arrays and slices. The explicit name `primitive:slice<u8>` and `primitive:array<u8>` can be used to match a slice or array of bytes, while square brackets `[u8]` will match either one. Empty square brackets, `[]`, will match any slice regardless of what it contains.
Preview:
* [`option -> []`](https://notriddle.com/rustdoc-demo-html-3/search-slice-array/std/index.html?search=option%20-%3E%20%5B%5D)
* [`[u8] -> str`](https://notriddle.com/rustdoc-demo-html-3/search-slice-array/std/index.html?search=%5Bu8%5D%20-%3E%20str)
* [`Box<[u8]> -> str`](https://notriddle.com/rustdoc-demo-html-3/search-slice-array/std/index.html?search=Box%3C%5Bu8%5D%3E%20-%3E%20str)
Motivation:
When type-based search was first landed, it was directly described as "incomplete". Here's [a comment] from the discussion thread:
[a comment]: https://github.com/rust-lang/rust/pull/23289#issuecomment-79437386
> This is looking really great, nice work! I can think of a number of cases that aren't quite covered by this, but I feel like this is a great improvement regardless and it can always be iterated on so I'm fine landing with a few known cases where it may not work :)
Filling out the missing functionality is going to mean adding support for more of Rust's [type expression] syntax, such as slices (in this PR), tuples, references, raw pointers, function pointers, and generics.
[type expression]: https://doc.rust-lang.org/reference/types.html#type-expressions
There does seem to be demand for this sort of thing, such as [this Discord message](https://discord.com/channels/442252698964721669/443150878111694848/1042145740065099796) expressing regret at rustdoc not supporting tuples in search queries.
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