Rustdoc markdown handling is currently split between:

- html::markdown, which contains all the meaty login
- markdown, which is only used for when rustdoc renders a standalone
  markdown file

Adds module-level doc-comment to markdown, and rename the function so
it's clear that it's doing IO (instead of just rendering to a string).

Signed-off-by: onur-ozkan <[email protected]>

Commit c95bbb59a9b22f9b838b15d28319185c1c884329 within rust-next
contains some changes required to be compatible with upcoming arbitraty
self types work. Roll RFL CI forward to the latest rust-next to include
that work.

Related:
rust-lang#130225
rust-lang#44874

These are all standard dictionary words and don't require hyphenation.

…r-ozkan

Refactor change detection for rustdoc and download-rustc

This pull request refactors the change detection logic in the build process by consolidating redundant code into a new helper method. The key changes include the removal of duplicate logic for checking changes in directories and the addition of a new method to handle this functionality.

Refactoring and code simplification:

* [`src/bootstrap/src/core/build_steps/tool.rs`](diffhunk://#diff-dc86e288bcf7b3ca3f8c127d3568fbafc785704883bc7fc336bd185910aed5daL588-R593): Removed redundant change detection logic and replaced it with a call to the new `check_for_changes` method.
* [`src/bootstrap/src/core/config/config.rs`](diffhunk://#diff-5f5330cfcdb0a89b85ac3547b761c3a45c2534a85c4aaae8fea88c711a7a65b2R2837-R2872): Added a new method `check_for_changes` to centralize the logic for detecting changes in specified directories since a given commit.
* [`src/bootstrap/src/core/config/config.rs`](diffhunk://#diff-5f5330cfcdb0a89b85ac3547b761c3a45c2534a85c4aaae8fea88c711a7a65b2L2728-R2740): Updated the existing change detection code to use the new `check_for_changes` method.

Cleanup:

* [`src/bootstrap/src/core/build_steps/tool.rs`](diffhunk://#diff-dc86e288bcf7b3ca3f8c127d3568fbafc785704883bc7fc336bd185910aed5daL13-R13): Removed the unused import `git` from the helpers module.

   r? `@AlbertLarsan68`

Compiletest: Custom differ

This adds support for a custom differ for compiletests. It’s purely visual and helps produce cleaner output when UI tests fail.

I’m using an environment variable for now since it’s experimental and I don’t want to drill the cli arguments all the way down. Also did a bit of general cleanup while I was at it.

This is how it looks [with debug info silenced](rust-lang#131182) (rust-lang#131182)
`COMPILETEST_DIFF_TOOL="/usr/bin/env difft --color always --background light --display side-by-side" ./x test tests/ui/parser`
![image](https://github.com/user-attachments/assets/f740ce50-7564-4469-be0a-86e24bc50eb8)

…, r=GuillaumeGomez

rustdoc: Document `markdown` module.

Rustdoc markdown handling is currently split between:

- html::markdown, which contains all the meaty login
- markdown, which is only used for when rustdoc renders a standalone markdown file

Adds module-level doc-comment to markdown, and rename the function so it's clear that it's doing IO (instead of just rendering to a string).

…l, r=fmease

Minor tweaks to `compare_impl_item.rs`

1. Stop using the `InstantiatedPredicates` struct for `hybrid_preds` in `compare_impl_item.rs`, since we never actually push anything into the `spans` part of it.
2. Remove redundant impl args and don't do useless identity substitution, prefer calling `instantiate_identity`.

…-tail-lifetimes, r=lcnr

Stabilize shorter-tail-lifetimes

Close rust-lang#131445
Tracked by rust-lang#123739

We found a test case `tests/ui/drop/drop_order.rs` that had not been covered by the change. The test fixture is fixed now with the correct expectation.

do not remove `.cargo` directory

If vendoring isn't used bootstrap removes `.cargo` directory, which prevents developers from setting certain options in the `.cargo/config.toml` file. This was introduced in rust-lang#97513 (specifically in [this commit](rust-lang@345eb14)). Also, since rust-lang#123942, vendoring is now possible even in git sources, which means we shouldn't remove `.cargo` directory in git sources anymore.

CI: rfl: use rust-next temporary commit

Commit c95bbb59a9b22f9b838b15d28319185c1c884329 within rust-next contains some changes required to be compatible with upcoming arbitraty self types work. Roll RFL CI forward to the latest rust-next to include that work.

Related:
rust-lang#130225
rust-lang#44874

r? `@ojeda`

try-job: x86_64-rust-for-linux

…r=jieyouxu

"innermost", "outermost", "leftmost", and "rightmost" don't need hyphens

These are all standard dictionary words and don't require hyphenation.

-----

Encountered an instance of this in error messages and it bugged me, so I
figured I'd fix it across the entire codebase.