Additionally add analogous test for early lints.

Also merge the two almost identical strikethrough tests together and document what the test tests.

Add Median of Medians fallback to introselect

Fixes rust-lang#102451.

This PR is a follow up to rust-lang#106997. It adds a Fast Deterministic Selection implementation as a fallback to the introselect algorithm used by `select_nth_unstable`. This allows it to guarantee O(n) worst case running time, while maintaining good performance in all cases.

This would fix rust-lang#102451, which was opened because the `select_nth_unstable` docs falsely claimed that it had O(n) worst case performance, even though it was actually quadratic in the worst case. rust-lang#106997 improved the worst case complexity to O(n log n) by using heapsort as a fallback, and this PR further improves it to O(n) (this would also make rust-lang#106933 unnecessary).
It also improves the actual runtime if the fallback gets called: Using a pathological input of size `1 << 19` (see the playground link in rust-lang#102451), calculating the median is roughly 3x faster using fast deterministic selection as a fallback than it is using heapsort.

The downside to this is less code reuse between the sorting and selection algorithms, but I don't think it's that bad. The additional algorithms are ~250 LOC with no `unsafe` blocks (I tried using unsafe to avoid bounds checks but it didn't noticeably improve the performance).
I also let it fuzz for a while against the current `select_nth_unstable` implementation to ensure correctness, and it seems to still fulfill all the necessary postconditions.

cc `@scottmcm` who reviewed rust-lang#106997

…rd, r=GuillaumeGomez

update `pulldown-cmark` to `0.9.3`

This PR updates `pulldown-cmark` to version `0.9.3`, which does two main things:
* Pulls in pulldown-cmark/pulldown-cmark#643 to fix rust-lang#111117
* Allows parsing strikethrough with single tildes, e.g. `~foo~` -> ~foo~. This matches the [GFM spec](https://github.github.com/gfm/#strikethrough-extension-).

Full changelog: pulldown-cmark/pulldown-cmark#646

…=eholk

Consider lint check attributes on match arms

Currently, lint check attributes on match arms have no effect for some lints. This PR makes some lint passes to take those attributes into account.

- `LateContextAndPass` for late lint doesn't update `last_node_with_lint_attrs` when it visits match arms. This leads to lint check attributes on match arms taking no effects on late lints that operate on the arms' pattern:

  ```rust
  match value {
      #[deny(non_snake_case)]
      PAT => {} // `non_snake_case` only warned due to default lint level
  }
  ```

  To be honest, I'm not sure whether this is intentional or just an oversight. I've dug the implementation history and searched up issues/PRs but couldn't find any discussion on this.

- `MatchVisitor` doesn't update its lint level when it visits match arms. This leads to check lint attributes on match arms taking no effect on some lints handled by this visitor, namely: `bindings_with_variant_name` and `irrefutable_let_patterns`.

  This seems to be a fallout from rust-lang#108504. Before 05082f5, when the visitor operated on HIR rather than THIR, check lint attributes for the said lints were effective. [This playground][play] compiles successfully on current stable (1.69) but fails on current beta and nightly.

  I wasn't sure where best to place the test for this. Let me know if there's a better place.

[play]: https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=38432b79e535cb175f8f7d6d236d29c3
[play-match]: https://play.rust-lang.org/?version=beta&mode=debug&edition=2021&gist=629aa71b7c84b269beadeba664e2221d

…illot

Always capture slice when pattern requires checking the length

Fixes rust-lang#111751

cc ``@zirconium-n,`` I see you were assigned to this but I've fixed some similar issues in the past and had an idea on how to investigate this.

…=wesleywiser

Don't print newlines in APITs

This is kind of a hack, but it gets the job done because the only "special" formatting that (afaict) `rustc_ast_pretty` does is break with newlines sometimes.

Fixes rust-lang/measureme#207

…lor-7, r=notriddle

Migrate GUI colors test to original CSS color format

Follow-up of rust-lang#111459.

r? ``@notriddle``

Remove ExpnKind::Inlined.

Suggested in rust-lang#111815 (comment)

r? ``@oli-obk``