[rustdoc] Fix invalid handling of "going back in history" when "go to only search result" setting is enabled
You can test the fix [here](https://rustdoc.crud.net/imperio/back-in-history-fix/lib2/index.html). Enable "Directly go to item in search if there is only one result", then search for `HasALongTraitWithParams` and finally go back to previous page. It should be back on the `index.html` page.
The reason for this bug is that the JS state is cached as is, so when we go back to the page, it resumes where it was left, somewhat (very weird), meaning the search is run again etc. The best way to handle this is to force the JS re-execution in this case so that it doesn't try to resume from where it left and then lead us back to the current page.
r? ``@notriddle``
rustdoc: Add search result item types after their name
Here what it looks like:

The idea is to improve accessibility by providing this information directly in the text and not only in the text color. Currently we already use it for doc aliases and for primitive types, so I extended it to all types.
r? `@notriddle`
rustdoc-search: clean up type unification and "unboxing"
This PR redesigns parameter matching, return matching, and generics matching to use a single function that compares two lists of types.
It also makes the algorithms more consistent, so the "unboxing" behavior where `Vec<i32>` is considered a match for `i32` works inside generics, and not just at the top level.
This feature extends rustdoc to support the syntax that most users will
naturally attempt to use to search for diverging functions.
Part of #60485
It's already possible to do this search with `primitive:never`, but
that's not what the Rust language itself uses, so nobody will try it if
they aren't told or helped along.
* There's no need to call `history.replaceState` right before
calling `searchState.hideResults`, which already does it.
* There's no need to implement hiding search results when that
is already implemented.
This change makes it so, instead of mixing string distance with
type unification, function signature search works by
mapping names to IDs at the start, reporting to the user any
cases where it had to make corrections, and then matches with
IDs when going through the items.
This only changes function searches. Name searches are left alone,
and corrections are only done when there's a single item in the
search query.
Fix "Directly go to item in search if there is only one result" setting
Part of #66181.
The setting was actually broken, so I fixed it when I added the GUI test.
r? `@notriddle`
This makes sense, since the search index has the information in it,
and it's more useful for function signature searches since a
function signature search's item type is, by definition, some type
of function (there's more than one, but not very many).
This tweak to the function signature search engine makes things so that,
if a type is repeated in the search query, it'll only match if the
function actually includes it that many times.
rustdoc: use restricted Damerau-Levenshtein distance for search
Based on https://github.com/rust-lang/rust/pull/108200, for the same rationale.
> This replaces the existing Levenshtein algorithm with the Damerau-Levenshtein algorithm. This means that "ab" to "ba" is one change (a transposition) instead of two (a deletion and insertion). More specifically, this is a restricted implementation, in that "ca" to "abc" cannot be performed as "ca" → "ac" → "abc", as there is an insertion in the middle of a transposition. I believe that errors like that are sufficiently rare that it's not worth taking into account.
Before this change, searching [`prinltn!`] listed `print!` first, followed by `println!`. With this change, `println!` matches more closely.
[`prinltn!`]: https://doc.rust-lang.org/nightly/std/?search=prinltn!
Based on https://github.com/rust-lang/rust/pull/108200, for the same
rationale.
> This replaces the existing Levenshtein algorithm with the
> Damerau-Levenshtein algorithm. This means that "ab" to "ba" is one change
> (a transposition) instead of two (a deletion and insertion). More
> specifically, this is a restricted implementation, in that "ca" to "abc"
> cannot be performed as "ca" → "ac" → "abc", as there is an insertion in the
> middle of a transposition. I believe that errors like that are sufficiently
> rare that it's not worth taking into account.
Before this change, searching `prinltn!` listed `print!` first, followed
by `println!`. With this change, `println!` matches more closely.