Rollup of 9 pull requests

Successful merges:

 - #86263 (Rustdoc: Report Layout of enum variants)
 - #88541 (Add regression test for #74400)
 - #88553 (Improve diagnostics for unary plus operators (#88276))
 - #88594 (More symbolic doc aliases)
 - #88648 (Correct “copies” to “moves” in `<Option<T> as From<T>>::from` doc, and other copyediting)
 - #88691 (Add a regression test for #88649)
 - #88694 (Drop 1.56 stabilizations from 1.55 release notes)
 - #88712 (Fix docs for `uX::checked_next_multiple_of`)
 - #88726 (Fix typo in `const_generics` replaced with `adt_const_params` note)

Failed merges:

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

Fix typo in `const_generics` replaced with `adt_const_params` note

Fix docs for `uX::checked_next_multiple_of`

Thanks to `@photino` for noticing this [here](https://github.com/rust-lang/rust/issues/88581#issuecomment-913982246).

r? `@joshtriplett`

`@rustbot` label: +A-docs +A-waiting-on-review

Drop 1.56 stabilizations from 1.55 release notes

r? `@Mark-Simulacrum`

Add a regression test for #88649

I noticed that #88649 does not have a regression test, so I add one in this PR.

The test fails with this without #88678:
```
error[E0080]: evaluation of constant value failed
  --> /checkout/src/test/ui/consts/issue-88649.rs:13:52
   |
LL |             Foo::Variant1(x) | Foo::Variant2(x) if x => {}
   |                                                    ^ StorageLive on a local that was already live

error: aborting due to previous error

For more information about this error, try `rustc --explain E0080`.
```

Correct “copies” to “moves” in `<Option<T> as From<T>>::from` doc, and other copyediting

The `impl<T> From<T> for Option<T>` has no `Copy` or `Clone` bound, so its operation is guaranteed to be a move. The call site might copy, but the function itself cannot.

Since that would have been a rather small PR, I also reviewed the other documentation in the file and made other improvements (in separate commits): adding periods and commas, linking `Deref::Target`, and clarifying what "a container" is in `FromIterator`.

More symbolic doc aliases

A bunch of small changes, mostly adding `#[doc(alias = "…")]` entries for symbolic `"…"`.

Also a small change in documentation of `const` keywords.

Improve diagnostics for unary plus operators (#88276)

This pull request improves the diagnostics emitted on parsing a unary plus operator. See #88276.

Before:

```
error: expected expression, found `+`
 --> src/main.rs:2:13
  |
2 |     let x = +1;
  |             ^ expected expression
```

After:

```
error: leading `+` is not supported
 --> main.rs:2:13
  |
2 |     let x = +1;
  |             ^
  |             |
  |             unexpected `+`
  |             help: try removing the `+`
```

Add regression test for #74400

Closes #74400 by adding a regression test.

Rustdoc: Report Layout of enum variants

Followup of #83501, Fixes #86253.

cc `@camelid`

`@rustbot` label A-rustdoc

`rustdoc`: compute correct line number for indented rust code blocks.

This PR fixes a bug in `rustdoc` where it computes the wrong line number for indented rust code blocks (and subsequent blocks) it finds in markdown strings. To fix this issue, we decrement the line number if we find characters between the code block and the preceding line ending. I noticed this issue as I was trying to use `rustdoc` to extract examples from The Rust Reference and run them through the [Rust Model Checker](https://github.com/model-checking/rmc).

Suggest deriving traits if possible

This only applies to builtin derives as I don't think there is a
clean way to get the available derives in typeck.

Closes #85851

Remove `hir::GenericBound::Unsized`

Rather than "moving" the `?Sized` bounds to the param bounds, just also check where clauses in `astconv`. I also did some related cleanup here, but that's not strictly neccesary. Also going to do a perf run here.

r? `@estebank`

2229: Don't move out of drop type

Fixes #88476

r? `@nikomatsakis`

Bump RLS submodule

r? `@Mark-Simulacrum`

Use index newtyping for TyVid

This is useful for using TyVid in types like VecGraph, and just otherwise seems like a small win.

Fix handling of +whole-archive native link modifier.

This PR fixes a bug in `add_upstream_native_libraries` that led to the `+whole-archive` modifier being ignored when linking in native libs.

~~Note that the PR does not address the situation when `+whole-archive` is combined with `+bundle`.~~
`@wesleywiser's` commit adds validation code that turns combining `+whole-archive` with `+bundle` into an error.

Fixes https://github.com/rust-lang/rust/issues/88085.

r? `@petrochenkov`
cc `@wesleywiser` `@gcoakes`

Move `confused_type_with_std_module` to `ResolverOutputs`

This eliminates untracked global state from `Session`.

BTreeMap/BTreeSet::from_iter: use bulk building to improve the performance

Bulk building is a common technique to increase the performance of building a fresh btree map. Instead of inserting items one-by-one, we sort all the items beforehand then create the BtreeMap in bulk.

Benchmark
```
./x.py bench library/alloc --test-args btree::map::from_iter
```

* Before
```
test btree::map::from_iter_rand_100                      ... bench:       3,694 ns/iter (+/- 840)
test btree::map::from_iter_rand_10_000                   ... bench:   1,033,446 ns/iter (+/- 192,950)
test btree::map::from_iter_seq_100                       ... bench:       5,689 ns/iter (+/- 1,259)
test btree::map::from_iter_seq_10_000                    ... bench:     861,033 ns/iter (+/- 118,815)
```

* After
```
test btree::map::from_iter_rand_100                      ... bench:       3,033 ns/iter (+/- 707)
test btree::map::from_iter_rand_10_000                   ... bench:     775,958 ns/iter (+/- 105,152)
test btree::map::from_iter_seq_100                       ... bench:       2,969 ns/iter (+/- 336)
test btree::map::from_iter_seq_10_000                    ... bench:     258,292 ns/iter (+/- 29,364)
```

Mmap the incremental data instead of reading it.

Instead of reading the full incremental state using `fs::read_file`, we memmap it using a private read-only file-backed map.
This allows the system to reclaim any memory we are not using, while ensuring we are not polluted by
outside modifications to the file.

Suggested in https://github.com/rust-lang/rust/pull/83036#issuecomment-800458082 by `@bjorn3`

Update Miri

Fixes #88671.

r? `@RalfJung`

This eliminates untracked global state from `Session`.

Pin bootstrap checksums and add a tool to update it automatically

⚠ ⚠ This is just a proactive hardening we're performing on the build system, and it's not prompted by any known compromise. If you're aware of security issues being exploited please [check out our responsible disclosure page](https://www.rust-lang.org/policies/security). ⚠ ⚠

---

This PR aims to improve Rust's supply chain security by pinning the checksums of the bootstrap compiler downloaded by `x.py`, preventing a compromised `static.rust-lang.org` from affecting building the compiler. The checksums are stored in `src/stage0.json`, which replaces `src/stage0.txt`. This PR also adds a tool to automatically update the bootstrap compiler.

The changes in this PR were originally discussed in [Zulip](https://zulip-archive.rust-lang.org/stream/241545-t-release/topic/pinning.20stage0.20hashes.html).

## Potential attack

Before this PR, an attacker who wanted to compromise the bootstrap compiler would "just" need to:

1. Gain write access to `static.rust-lang.org`, either by compromising DNS or the underlying storage.
2. Upload compromised binaries and corresponding `.sha256` files to `static.rust-lang.org`.

There is no signature verification in `x.py` as we don't want the build system to depend on GPG. Also, since the checksums were not pinned inside the repository, they were downloaded from `static.rust-lang.org` too: this only protected from accidental changes in `static.rust-lang.org` that didn't change the `*.sha256` files. The attack would allow the attacker to compromise past and future invocations of `x.py`.

## Mitigations introduced in this PR

This PR adds pinned checksums for all the bootstrap components in `src/stage0.json` instead of downloading the checksums from `static.rust-lang.org`. This changes the attack scenario to:

1. Gain write access to `static.rust-lang.org`, either by compromising DNS or the underlying storage.
2. Upload compromised binaries to `static.rust-lang.org`.
3. Land a (reviewed) change in the `rust-lang/rust` repository changing the pinned hashes.

Even with a successful attack, existing clones of the Rust repository won't be affected, and once the attack is detected reverting the pinned hashes changes should be enough to be protected from the attack. This also enables further mitigations to be implemented in following PRs, such as verifying signatures when pinning new checksums (removing the trust on first use aspect of this PR) and adding a check in CI making sure a PR updating the checksum has not been tampered with (see the future improvements section).

## Additional changes

There are additional changes implemented in this PR to enable the mitigation:

* The `src/stage0.txt` file has been replaced with `src/stage0.json`. The reasoning for the change is that there is existing tooling to read and manipulate JSON files compared to the custom format we were using before, and the slight challenge of manually editing JSON files (no comments, no trailing commas) are not a problem thanks to the new `bump-stage0`.

* A new tool has been added to the repository, `bump-stage0`. When invoked, the tool automatically calculates which release should be used as the bootstrap compiler given the current version and channel, gathers all the relevant checksums and updates `src/stage0.json`. The tool can be invoked by running:

  ```
  ./x.py run src/tools/bump-stage0
  ```

* Support for downloading releases from `https://dev-static.rust-lang.org` has been removed, as it's not possible to verify checksums there (it's customary to replace existing artifacts there if a rebuild is warranted). This will require a change to the release process to avoid bumping the bootstrap compiler on beta before the stable release.

## Future improvements

* Add signature verification as part of `bump-stage0`, which would require the attacker to also obtain the release signing keys in order to successfully compromise the bootstrap compiler. This would be fine to add now, as the burden of installing the tool to verify signatures would only be placed on whoever updates the bootstrap compiler, instead of everyone compiling Rust.

* Add a check on CI that ensures the checksums in `src/stage0.json` are the expected ones. If a PR changes the stage0 file CI should also run the `bump-stage0` tool and fail if the output in CI doesn't match the committed file. This prevents the PR author from tweaking the output of the tool manually, which would otherwise be close to impossible for a human to detect.

* Automate creating the PRs bumping the bootstrap compiler, by setting up a scheduled job in GitHub Actions that runs the tool and opens a PR.

* Investigate whether a similar mitigation can be done for "download from CI" components like the prebuilt LLVM.

r? `@Mark-Simulacrum`

Rollup of 6 pull requests

Successful merges:

 - #88602 (Add tests for some const generics issues)
 - #88647 (Document when to use Windows' `symlink_dir` vs. `symlink_file`)
 - #88659 (Remove SmallVector mention)
 - #88661 (Correct typo)
 - #88673 (Fix typo: needede -> needed)
 - #88685 (⬆ rust-analyzer)

Failed merges:

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

This only applies to builtin derives as I don't think there is a
clean way to get the available derives in typeck.

Closes #85851

Change scope of temporaries in match guards

Each pattern in a match arm has its own copy of the match guard in MIR, with its own temporary, so it has to be dropped before the the guards are joined to the single copy of the arm. This PR changes `then_else_break` to allow it to put the temporary in the innermost scope possible. This change isn't done for `if` expressions because that affects a large number of mir-opt tests and could more significantly affect performance.

closes #88649

r? `@oli-obk`

⬆ rust-analyzer