compiler-builtins subtree update

Subtree update of `compiler-builtins` to 2cdde03.

Created using https://github.com/rust-lang/josh-sync.

Fixes: rust-lang/rust#144076

r? `@ghost`

flt2dec: replace for loop by iter_mut

Perf is explored in rust-lang/rust#144118, which initially showed small losses, but then also showed significant gains. Both are real, but given the smallness of the losses, this seems a good change.

stdarch subtree update

Subtree update of `stdarch` to rust-lang/stdarch@5531955.

Created using https://github.com/rust-lang/josh-sync.

I saw that there were non-trivial changes made to `std_detect` in `stdarch` recently. So I want to get them merged here before we move forward with rust-lang/rust#143412.

r? `@folkertdev`

Implement AST visitors using a derive macro.

AST visitors are large and error-prone beasts. This PR attempts to write them using a derive macro.

The design uses three traits: `Visitor`, `Visitable`, `Walkable`.
- `Visitor` is the trait implemented by downstream crates, it lists `visit_stuff` methods, which call `Walkable::walk_ref` by default;
- `Walkable` is derived using the macro, the generated `walk_ref` method calls `Visitable::visit` on each component;
- `Visitable` is implemented by `common_visitor_and_walkers` macro, to call the proper `Visitor::visit_stuff` method if it exists, to call `Walkable::walk_ref` if there is none.

I agree this is quite a lot of spaghetti macros. I'm open to suggestions on how to reduce the amount of boilerplate code.

If this PR is accepted, I believe the same design can be used for the HIR visitor.

Consider parent predicates in ImpossiblePredicates pass.

This pass is double edged. It avoids some ICEs (yay!) but also degrades diagnostics from constant evaluation.

Fixes rust-lang/rust#121363
Fixes rust-lang/rust#131507
Fixes rust-lang/rust#140100
Fixes rust-lang/rust#140365

Enforce that PR CI jobs are a subset of Auto CI jobs modulo carve-outs

### Background

Currently, it is possible for a PR with red PR-only CI to pass Auto CI, then all subsequent PR CI runs will be red until that is fixed, even in completely unrelated PRs. For instance, this happened with PR-CI-only Spellcheck (rust-lang/rust#144183).

See more discussions at [#t-infra > Spellcheck workflow now fails on all PRs (tree bad?)](https://rust-lang.zulipchat.com/#narrow/channel/242791-t-infra/topic/Spellcheck.20workflow.20now.20fails.20on.20all.20PRs.20.28tree.20bad.3F.29/with/529769404).

### CI invariant: PR CI jobs are a subset of Auto CI jobs modulo carve-outs

To prevent red PR CI in completely unrelated subsequent PRs and PR CI runs, we need to maintain an invariant that **PR CI jobs are a subset of Auto CI jobs modulo carve-outs**.

This is **not** a "strict" subset relationship: some jobs necessarily have to differ under PR CI and Auto CI environments, at least in the current setup. Still, we can try to enforce a weaker "subset modulo carve-outs" relationship between CI jobs and their corresponding Auto jobs. For instance:

- `x86_64-gnu-tools` will have `auto`-only env vars like `DEPLOY_TOOLSTATES_JSON: toolstates-linux.json`.
- `tidy` will want to `continue_on_error: true` in PR CI to allow for more "useful" compilation errors to also be reported, whereas it should be `continue_on_error: false` in Auto CI to prevent wasting Auto CI resources.

The **carve-outs** are:

1. `env` variables.
2. `continue_on_error`.

We enforce this invariant through `citool`, so only affects job definitions that are handled by `citool`. Notably, this is not sufficient *alone* to address the CI-only Spellcheck issue (rust-lang/rust#144183). To carry out this enforcement, we modify `citool` to auto-register PR jobs as Auto jobs with `continue_on_error` overridden to `false` **unless** there's an overriding Auto job for the PR job of the same name that only differs by the permitted **carve-outs**.

### Addressing the Spellcheck PR-only CI issue

Note that Spellcheck currently does not go through `citool` or `bootstrap`, and is its own GitHub Actions workflow. To actually address the PR-CI-only Spellcheck issue (rust-lang/rust#144183), and carry out the subset-modulo-carve-outs enforcement universally, this PR additionally **removes the current Spellcheck implementation** (a separate GitHub Actions Workflow). That is incompatible with Homu unless we do some hacks in the main CI workflow.

This effectively partially reverts rust-lang/rust#134006 (the separate workflow part, not the tidy extra checks component), but is not prejudice against relanding the `typos`-based spellcheck in another implementation that goes through the usual bootstrap CI workflow so that it does work with Homu. The `typos`-based spellcheck seems to have a good false-positive rate.

Closes rust-lang/rust#144183.

---

r? infra-ci

Various refactors to the LTO handling code (part 2)

Continuing from rust-lang/rust#143388 this removes a bit of dead code and moves the LTO symbol export calculation from individual backends to cg_ssa.

Do not run per-module late lints if they can be all skipped

We run ~70 late lints for all dependencies even if they use `--cap-lints=allow`, which seems wasteful. It looks like these lints are super fast (unlike early lints), but still.

r? `@ghost`

Skip walking into param-env component if it has no placeholder/re-var

Although it only provides a minor perf improvement, it seems like it could matter in more pathological cases.

…ler-errors

Avoid unnecessary `new_adt`/`new_fn_def` calls.

They can be skipped if there are no arguments, avoiding the "relate" operation work and also the subsequent interning.

r? `@ghost`

…rrors

Preintern some `TyKind::Bound` values

The new trait solver produces a lot of these.

r? `@compiler-errors`

Free disk space on Windows 2025 runners

I've managed to reduce the time deletion takes by:

 - Using powershell, which is generally faster for filesystem operations than msys2
 - Performing deletions concurrently then waiting for them all to complete

It still takes 2-10 mins but that's not too bad.

Add dynamic support for aarch64 LSE atomic ops on linux targets
when optimized-compiler-builtins is not enabled.

A hook, __enable_rust_lse, is provided for the runtime to enable
them if available. A future patch will use this to enable them
if available.

The resulting asm should exactly match that of LLVM's compiler-rt
builtins, though the symbol naming for the support function and
global does not.

compiler-builtins: plumb LSE support for aarch64 on linux/gnu when optimized-compiler-builtins not enabled

Add dynamic support for aarch64 LSE atomic ops on linux/gnu targets when optimized-compiler-builtins is not enabled.

Enabling LSE is the primary motivator for rust-lang/rust#143689, though extending the rust version doesn't seem too farfetched. Are there more details which I have overlooked which make this impractical? I've tested this on an aarch64 host with LSE.

r? ```````@tgross35```````

Port `#[allow_internal_unsafe]` to the new attribute system

Related to rust-lang/rust#131229 (comment).

r? ````@jdonszelmann````

…tolnay

Stabilize `unsigned_signed_diff` feature

This closes [tracking issue](rust-lang/rust#126041) and stabilises `checked_signed_diff`

Closes: rust-lang/rust#126041

Rename `begin_panic_handler` to `panic_handler`

Part of rust-lang/rust#116005

compiler-builtins subtree update

Subtree update of `compiler-builtins` to 87a66ec.

Created using https://github.com/rust-lang/josh-sync.

r? ``@ghost``

Fix build/doc/test of error index generator

It is essentially a RustcPrivate tool, so it should be treated as such using the new `RustcPrivateCompilers` infra. Found while working on unrelated `doc` cleanups.

r? ````@jieyouxu````

…tmcm

Derive `Hash` for rustc_public types

This derives `Hash` for the rustc_public versions of `Rvalue`, `Place`, `Span`, and all the types they contain. As far as I can tell, the internal versions of all these types already implement `Hash`, so it would be helpful if the public versions implemented it too!

…umeGomez

doc(library): Fix Markdown in `Iterator::by_ref`

This patch fixes the Markdown formatting in `std::core::iter::Iterator::by_ref`. Code is used inside a link without the backticks around the code.

Fix doc comment of File::try_lock and File::try_lock_shared

The doc comments of functions `File::try_lock` and `File::try_lock_shared` stabilized today in version 1.89.0 document an incorrect type of `Ok`.

The result type was changed in rust-lang/rust#139343 after the latest change to the doc comments in rust-lang/rust#136876.

Rollup of 9 pull requests

Successful merges:

 - rust-lang/rust#144705 (compiler-builtins: plumb LSE support for aarch64 on linux/gnu when optimized-compiler-builtins not enabled)
 - rust-lang/rust#144857 (Port `#[allow_internal_unsafe]` to the new attribute system)
 - rust-lang/rust#144900 (Stabilize `unsigned_signed_diff` feature)
 - rust-lang/rust#144903 (Rename `begin_panic_handler` to `panic_handler`)
 - rust-lang/rust#144974 (compiler-builtins subtree update)
 - rust-lang/rust#145007 (Fix build/doc/test of error index generator)
 - rust-lang/rust#145018 (Derive `Hash` for rustc_public types)
 - rust-lang/rust#145045 (doc(library): Fix Markdown in `Iterator::by_ref`)
 - rust-lang/rust#145046 (Fix doc comment of File::try_lock and File::try_lock_shared)

r? `@ghost`
`@rustbot` modify labels: rollup

Rollup of 19 pull requests

Successful merges:

 - rust-lang/rust#144400 (`tests/ui/issues/`: The Issues Strike Back [3/N])
 - rust-lang/rust#144764 ([codegen] assume the tag, not the relative discriminant)
 - rust-lang/rust#144807 (Streamline config in bootstrap)
 - rust-lang/rust#144899 (Print CGU reuse statistics in `-Zprint-mono-items`)
 - rust-lang/rust#144909 (Add new `test::print_merged_doctests_times` used by rustdoc to display more detailed time information)
 - rust-lang/rust#144912 (Resolver: introduce a conditionally mutable Resolver for (non-)speculative resolution.)
 - rust-lang/rust#144914 (Add support for `ty::Instance` path shortening in diagnostics)
 - rust-lang/rust#144931 ([win][arm64ec] Fix msvc-wholearchive for Arm64EC)
 - rust-lang/rust#144999 (coverage: Remove all unstable support for MC/DC instrumentation)
 - rust-lang/rust#145009 (A couple small changes for rust-analyzer next-solver work)
 - rust-lang/rust#145030 (GVN:  Do not flatten derefs with ProjectionElem::Index. )
 - rust-lang/rust#145042 (stdarch subtree update)
 - rust-lang/rust#145047 (move `type_check` out of `compute_regions`)
 - rust-lang/rust#145051 (Prevent name collisions with internal implementation details)
 - rust-lang/rust#145053 (Add a lot of NLL `known-bug` tests)
 - rust-lang/rust#145055 (Move metadata symbol export from exported_non_generic_symbols to exported_symbols)
 - rust-lang/rust#145057 (Clean up some resolved test regressions of const trait removals in std)
 - rust-lang/rust#145068 (Readd myself to review queue)
 - rust-lang/rust#145070 (Add minimal `armv7a-vex-v5` tier three target)

r? `@ghost`
`@rustbot` modify labels: rollup

This updates the rust-version file to ffb9d94dcf4ade0d534842be3672d5e9f47e1333.

Pull recent changes from https://github.com/rust-lang/rust via Josh.

Upstream ref: ffb9d94dcf4ade0d534842be3672d5e9f47e1333
Filtered ref: 2f31646

This merge was created using https://github.com/rust-lang/josh-sync.