This is a continuation of #60109, which noted that while the ADX
intrinsics were stabilized, the corresponding target feature never was.

This PR follows the same general structure and stabilizes the ADX target
feature.

Rollup of 5 pull requests

Successful merges:

 - #90621 (Stabilise `aarch64_target_feature`)
 - #93977 (Type params and assoc types have unit metadata if they are sized)
 - #94670 (Improve `expect` impl and handle `#[expect(unfulfilled_lint_expectations)]` (RFC 2383))
 - #94884 (Fix remaining meta-variable expression TODOs)
 - #94931 (update miri)

Failed merges:

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

update miri

Fixes https://github.com/rust-lang/rust/issues/94910
r? `@ghost`

Fix remaining meta-variable expression TODOs

As promised on https://github.com/rust-lang/rust/pull/93545.

cc #83527
cc `@mark-i-m`
cc `@petrochenkov`

Improve `expect` impl and handle `#[expect(unfulfilled_lint_expectations)]` (RFC 2383)

This PR updates unstable `ExpectationIds` in stashed diagnostics and adds some asserts to ensure that the stored expectations are really empty in the end. Additionally, it handles the `#[expect(unfulfilled_lint_expectations)]` case.

According to the [Errors and lints docs](https://rustc-dev-guide.rust-lang.org/diagnostics.html#diagnostic-levels) the `error` level should only be used _"when the compiler detects a problem that makes it unable to compile the program"_. As this isn't the case with `#[expect(unfulfilled_lint_expectations)]` I decided to only create a warning. To avoid adding a new lint only for this case, I simply emit a `unfulfilled_lint_expectations` diagnostic with an additional note.

---

r? `@wesleywiser` I'm requesting a review from you since you reviewed the previous PR https://github.com/rust-lang/rust/pull/87835. You are welcome to reassign it if you're busy 🙃

rfc: [RFC-2383](https://rust-lang.github.io/rfcs/2383-lint-reasons.html)

tracking issue: https://github.com/rust-lang/rust/issues/85549

cc: `@flip1995` In case you're also interested in this :)

Type params and assoc types have unit metadata if they are sized

Extend the logic in `Pointee` projection to ensure that we can satisfy `<T as Pointee>::Metadata = ()` if `T: Sized`.

cc: `@SimonSapin` and #93959

Stabilise `aarch64_target_feature`

This PR stabilises `aarch64_target_feature` - see https://github.com/rust-lang/rust/issues/90620

Update Clippy

r? `@Manishearth`

A few days delayed, because I recovered from a cold last week and couldn't get myself to do the sync, sorry. 🙃

Add riscv32im-unknown-none-elf built-in target triple.

* Add built-in target `riscv32im-unknown-none-elf`.
* Update `platform-support.md` to list it as a Tier 3 target.

Below are details on how this target meets the requirements for tier 3:

> A tier 3 target must have a designated developer or developers (the "target maintainers") on record to be CCed when issues arise regarding the target. (The mechanism to track and CC such developers may evolve over time.)

I would be willing to be a target maintainer, though I would appreciate if others with more experience around RISC-V volunteered to help with that as well.

> Targets must use naming consistent with any existing targets; for instance, a target for the same CPU or OS as an existing Rust target should use the same name for that CPU or OS. Targets should normally use the same names and naming conventions as used elsewhere in the broader ecosystem beyond Rust (such as in other toolchains), unless they have a very good reason to diverge. Changing the name of a target can be highly disruptive, especially once the target reaches a higher tier, so getting the name right is important even for a tier 3 target.

Uses the same naming as the LLVM target, and the same convention as many other bare-metal targets.

> Target names should not introduce undue confusion or ambiguity unless absolutely necessary to maintain ecosystem compatibility. For example, if the name of the target makes people extremely likely to form incorrect beliefs about what it targets, the name should be changed or augmented to disambiguate it.

I don't believe there is any ambiguity here.

> Tier 3 targets may have unusual requirements to build or use, but must not create legal issues or impose onerous legal terms for the Rust project or for Rust developers or users.

I don't see any legal issues here.

> The target must not introduce license incompatibilities.
> Anything added to the Rust repository must be under the standard Rust license (MIT OR Apache-2.0).
> The target must not cause the Rust tools or libraries built for any other host (even when supporting cross-compilation to the target) to depend on any new dependency less permissive than the Rust licensing policy. This applies whether the dependency is a Rust crate that would require adding new license exceptions (as specified by the tidy tool in the rust-lang/rust repository), or whether the dependency is a native library or binary. In other words, the introduction of the target must not cause a user installing or running a version of Rust or the Rust tools to be subject to any new license requirements.
> If the target supports building host tools (such as rustc or cargo), those host tools must not depend on proprietary (non-FOSS) libraries, other than ordinary runtime libraries supplied by the platform and commonly used by other binaries built for the target. For instance, rustc built for the target may depend on a common proprietary C runtime library or console output library, but must not depend on a proprietary code generation library or code optimization library. Rust's license permits such combinations, but the Rust project has no interest in maintaining such combinations within the scope of Rust itself, even at tier 3.
> Targets should not require proprietary (non-FOSS) components to link a functional binary or library.
> "onerous" here is an intentionally subjective term. At a minimum, "onerous" legal/licensing terms include but are not limited to: non-disclosure requirements, non-compete requirements, contributor license agreements (CLAs) or equivalent, "non-commercial"/"research-only"/etc terms, requirements conditional on the employer or employment of any particular Rust developers, revocable terms, any requirements that create liability for the Rust project or its developers or users, or any requirements that adversely affect the livelihood or prospects of the Rust project or its developers or users.

I see no issues with any of the above.

> Neither this policy nor any decisions made regarding targets shall create any binding agreement or estoppel by any party. If any member of an approving Rust team serves as one of the maintainers of a target, or has any legal or employment requirement (explicit or implicit) that might affect their decisions regarding a target, they must recuse themselves from any approval decisions regarding the target's tier status, though they may otherwise participate in discussions.
> This requirement does not prevent part or all of this policy from being cited in an explicit contract or work agreement (e.g. to implement or maintain support for a target). This requirement exists to ensure that a developer or team responsible for reviewing and approving a target does not face any legal threats or obligations that would prevent them from freely exercising their judgment in such approval, even if such judgment involves subjective matters or goes beyond the letter of these requirements.

Only relevant to those making approval decisions.

> Tier 3 targets should attempt to implement as much of the standard libraries as possible and appropriate (core for most targets, alloc for targets that can support dynamic memory allocation, std for targets with an operating system or equivalent layer of system-provided functionality), but may leave some code unimplemented (either unavailable or stubbed out as appropriate), whether because the target makes it impossible to implement or challenging to implement. The authors of pull requests are not obligated to avoid calling any portions of the standard library on the basis of a tier 3 target not implementing those portions.

`core` and `alloc` can be used. `std` cannot be used as this is a bare-metal target.

> The target must provide documentation for the Rust community explaining how to build for the target, using cross-compilation if possible. If the target supports running tests (even if they do not pass), the documentation must explain how to run tests for the target, using emulation if possible or dedicated hardware if necessary.

Use `--target=x86_64-unknown-none-elf` option to cross compile, just like any target. The target does not support running tests.

> Tier 3 targets must not impose burden on the authors of pull requests, or other developers in the community, to maintain the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on a tier 3 target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding a tier 3 target, unless they have opted into such messages.
> Backlinks such as those generated by the issue/PR tracker when linking to an issue or PR are not considered a violation of this policy, within reason. However, such messages (even on a separate repository) must not generate notifications to anyone involved with a PR who has not requested such notifications.

I don't foresee this being a problem.

> Patches adding or updating tier 3 targets must not break any existing tier 2 or tier 1 target, and must not knowingly break another tier 3 target without approval of either the compiler team or the maintainers of the other tier 3 target.
> In particular, this may come up when working on closely related targets, such as variations of the same architecture with different features. Avoid introducing unconditional uses of features that another variation of the target may not have; use conditional compilation or runtime detection, as appropriate, to let each target run code supported by that target.

No other targets should be affected by the pull request.

Fix definition of Box in ssa-analysis-regression-50041.rs

The Box in liballoc always has a field for the allocator. It is quite
hard to support both the old and new definition of Box in cg_clif so
this change uses the new definition in this test too.

Rustup

r? `@ghost`

changelog: none

librustdoc: adopt let else in more places

Continuation of #89933, #91018, #91481, #93046, #93590, #94011.

I have extended my clippy lint to also recognize tuple passing and match statements. The diff caused by fixing it is way above 1 thousand lines. Thus, I split it up into multiple pull requests to make reviewing easier. This PR handles librustdoc.

rustdoc-json: Clean Up json format

No semantic changes, but better names

Closes https://github.com/rust-lang/rust/issues/94198

Closes https://github.com/rust-lang/rust/issues/94889

r? `@CraftSpider`

`@rustbot` modify labels: +A-rustdoc-json +T-rustdoc +C-cleanup

Identify anonymous lifetimes by their DefId in HIR.

`ParamName::Fresh` currently identifies anonymous lifetimes by an `usize` index computed from the number of lifetimes in scope. This makes the behaviour of lowering dependent on the contents of the surrounding item in unpredictable ways.

This PR replaces this index by the `LocalDefId` of the synthetized generic lifetime parameter. This makes obvious which parameter the lifetime corresponds to.

Closes #94198

Fixes #94889

bootstrap: untangle static-libstdcpp & llvm-tools

Previously, the static-libstdcpp setting was tied to llvm-tools such
that enabling the latter always enabled the latter. This seems
unfortunate, since it is entirely reasonable for someone to want to
_not_ statically link stdc++, but _also_ want to build the llvm-tools.
This patch therefore separates the two settings such that neither
implies the other.

On its own, that would change the default behavior in a way that's
likely to surprise users. Specifically, users who build llvm-tools
_likely_ want those tools to be statically compiled against libstdc++,
since otherwise users with older GLIBCXX will be unable to run the
vended tools. So, we also flip the default for the `static-libstdcpp`
setting such that builds always link statically against libstdc++ by
default, but it's _possible_ to opt out.

See also #94719.

Rollup of 5 pull requests

Successful merges:

 - #93292 (Implement `BITS` constant for non-zero integers)
 - #94777 (Update armv7-unknown-linux-uclibceabi platform support page.)
 - #94816 (Add `Atomic*::get_mut_slice`)
 - #94844 (Reduce rustbuild bloat caused by serde_derive)
 - #94907 (Omit stdarch test crates from the rust-src component)

Failed merges:

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

Omit stdarch test crates from the rust-src component

These crates aren't necessary for building the standard library. This saves 30MB of disk space.

Fixes #94906

Reduce rustbuild bloat caused by serde_derive

This reduces the size of the `.text` section from 10.1MiB (6.2MiB for just rustbuild code) to 9.3MiB (5.3MiB for just rustbuild code).

This also reduces compile time from ~6.1s for incr recompilation to ~5.6s.

r? `@Mark-Simulacrum`

Add `Atomic*::get_mut_slice`

This PR adds the inverse of `Atomic*::from_mut_slice` introduced in #94384 with the following API:
```rust
// core::sync::atomic

impl Atomic* {
    fn get_mut_slice(this: &mut [Self]) -> &mut [*];
}
```

cc `@cuviper`

-----

For now I've used the same tracking issue as `Atomic*::from_mut_slice`, should I open a new one?

Update armv7-unknown-linux-uclibceabi platform support page.

A few edits and fixes to the support page for the armv7-unknown-linux-uclibceabi target.

Implement `BITS` constant for non-zero integers

This adds the associated [`BITS`](https://doc.rust-lang.org/stable/std/primitive.usize.html#associatedconstant.BITS) constant to `NonZero{U,I}{8,16,32,64,128,size}`.

This is useful when a type alias refers to either a regular or non-zero integer.

Enable conditional checking of values in the Rust codebase

This pull-request enable conditional checking of (well known) values in the Rust codebase.

Well known values were added in https://github.com/rust-lang/rust/pull/94362. All the `target_*` values are taken from all the built-in targets which is why some extra values were needed do be added as they are not (yet ?) defined in any built-in targets.

r? `@Mark-Simulacrum`

The Box in liballoc always has a field for the allocator. It is quite
hard to support both the old and new definition of Box in cg_clif so
this change uses the new definition in this test too.

These crates aren't necessary for building the standard library. This
saves 30MB of disk space.

Fixes #94906

new lint: `only_used_in_recursion`

changed:
- added `only_used_in_recursion`.
- fixed code that variables are only used in recursion.
- this would not lint when `unused_variable`

This fixes: #8390

-----

changelog: add lint [`only_used_in_recursion`]

Gather LLVM PGO profiles from `rustc-perf` suite on real-world crates

This PR expands the benchmark suite used to gather LLVM PGO profiles in CI from `libcore` to several real-world crates. I hand-picked a few crates, but the list is up for debate.

Previous results that we got from running `syn,cargo,serde` looked pretty [good](https://perf.rust-lang.org/compare.html?start=2631aeef823a9e16d31f999d3f07001e5fcc4b3d&end=abf097afa10dde1aa3d8a1d422724a46aab79bf3).

Running `libcore` + `rustc-perf` with some number of crates is repeated now (and for BOLT it will also be needed), so maybe we can extract it to a bash function?

r? `@Mark-Simulacrum`

new lint that detects useless match expression

fixes #7040

changelog: Add new  lint [`needless_match`] under complexity lint group