rust-lang#134808 made --bless remove empty
expected files. Remove some empty files that were causing noise in
unrelated `--bless` invocations.

…ccurrences)

…uillaumeGomez

rustdoc-json: Include items in stripped modules in `Crate::paths`.

Closes rust-lang#135309

When we're running rustdoc-json, we should err on the side of adding more items to `Cache::paths`, as that directly becomes `Crate::paths` in the output.

r? `@GuillaumeGomez.` Best reviewed commit-by-commit.

Update the explanation for why we use box_new in vec!

The perf run in this PR demonstrates that there is no longer a dramatic change in compile time with the intrinsic `box_new` vs calling `Box::new`, but I've locally confirmed that there is still a dramatic change in stack use.

… r=compiler-errors

Remove allocations from case-insensitive comparison to keywords

Follows up on work in 99d02fb, expanding the alloc-free comparisons to more cases of case-insensitive keyword matching.

r? ghost for perf

…rors

De-abstract tagged ptr and make it covariant

In rust-lang#135272 I needed to use a tagged ptr in `hir::TyKind` in order to not regress hir type sizes. Unfortunately the existing `CopyTaggedPtr` abstraction is insufficient as it makes the `'hir` lifetime invariant.

I spent some time trying to keep existing functionality while making it covariant but in the end I realised that actually we dont use *any* of this code *anywhere* in rustc, so I've just removed everything and replaced it with a much less general abstraction that is suitable for what I need in rust-lang#135272.

Idk if anyone has a preference for just keeping all the abstractions here in case anyone needs them in the future 🤷‍♀️

Remove some empty expected files to fix blessing

rust-lang#134808 made --bless remove empty
expected files. Remove some empty files that were causing noise in
unrelated `--bless` invocations.

…s, r=compiler-errors

Update unstable lint docs to include required feature attributes

closes rust-lang#135298

## Summary
This PR updates the documentation examples for the following unstable lints to ensure they include the necessary feature attributes for proper usage:

- fuzzy_provenance_casts
- lossy_provenance_casts
- unqualified_local_imports
- test_unstable_lint

## Changes Made:

- Added the appropriate #![feature(...)] attributes to the example code for each lint.
- Updated the examples to produce correct and meaningful warnings, ensuring they align with current lint behavior.

Reference:
- Used the `must_not_suspend` lint documentation as a template for these updates.

…er-errors

Deny various clippy lints

Almost all of these clippy lints have zero occurrences. Two of them have one each, and this PR fixes those.

…ouxu

run_make_support: add `#![warn(unreachable_pub)]`

This PR enables the [`unreachable_pub`](https://doc.rust-lang.org/rustc/lints/listing/allowed-by-default.html#unreachable-pub) lint as warn in the `run_make_support` crate.

Related to rust-lang/compiler-team#773

r? `@jieyouxu`