Co-authored-by: fee1-dead <ent3rm4n@gmail.com>

Currently stable users can't benefit from this because GlobaAlloc doesn't support
alignment-changing realloc and neither do most posix allocators.
So in practice it always results in an extra memcpy.

…e impl is implemented on a type alias

"It's" expands to "it is". "Its" is the possessive form.

…n-ty-alias, r=notriddle

Fix impl stripped in rustdoc HTML whereas it should not be in case the impl is implemented on a type alias

Fixes rust-lang#119015.

I talked about it a bit with ```@petrochenkov.``` They might change what `EffectiveVisibilities` return for impl items like this one and make them not only reachable but also re-exported, which would fix this case. It could also potentially break other things, so it'll be done whenever they can and then we can check together.

Surprisingly, this fix is making rustdoc even closer to rustc in term of errors (the CI currently fails because currently accepted broken codes aren't working anymore with this change). Not sure exactly why though. This is linked to rust-lang#110631 from what I could find.

So either I'm missing something here, or we consider it's ok and we consider the failing tests as "should fail" and I'll update `rustdoc-ui` ones.

r? ```@notriddle```

Ensure `callee_id`s are body owners

This PR makes the `callee_id` argument of Clippy's `implements_trait_with_env` optional, and when it is passed, ensures it is a body owner.

rust-lang#118661 added the `callee_id` parameter to alleviate an ICE. Specifically, the `callee_id` is used to determine an "effect arg" in certain situations.

Frankly, I [do not completely understand](rust-lang#118661 (comment)) what an "effect arg" is. But the code that determines it seems to require that `callee_id` is a body owner:
- https://github.com/rust-lang/rust/blob/1ead4761e9e2f056385768614c23ffa7acb6a19e/src/tools/clippy/clippy_utils/src/ty.rs#L286-L288
- https://github.com/rust-lang/rust/blob/1ead4761e9e2f056385768614c23ffa7acb6a19e/compiler/rustc_middle/src/ty/util.rs#L834
- https://github.com/rust-lang/rust/blob/1ead4761e9e2f056385768614c23ffa7acb6a19e/compiler/rustc_middle/src/hir/map/mod.rs#L372

In the current head, some def ids passed as `callee_id`s are not body owners. This PR fixes that.

cc ``@rust-lang/clippy``

r? ``@fee1-dead``

…ilstrieb

Remove special handling of `box` expressions from parser

rust-lang#108471 added a temporary hack to parse `box expr`. It's been almost a year since then, so I think it's safe to remove the special handling.

As a drive-by cleanup, move `parser/removed-syntax*` tests to their own directory.

…viper

Remove alignment-changing in-place collect

This removes the alignment-changing in-place collect optimization introduced in rust-lang#110353
Currently stable users can't benefit from the optimization because GlobaAlloc doesn't support alignment-changing realloc and neither do most posix allocators. So in practice it has a negative impact on performance.

Explanation from rust-lang#120091 (comment):

> > You mention that in case of alignment mismatch -- when the new alignment is less than the old -- the implementation calls `mremap`.
>
> I was trying to note that this isn't really the case in practice, due to the semantics of Rust's allocator APIs. The only use of the allocator within the `in_place_collect` implementation itself is [a call to `Allocator::shrink()`](https://github.com/rust-lang/rust/blob/db7125f008cfd72e8951c9a863178956e2cbacc3/library/alloc/src/vec/in_place_collect.rs#L299-L303), which per its documentation [allows decreasing the required alignment](https://doc.rust-lang.org/1.75.0/core/alloc/trait.Allocator.html). However, in stable Rust, the only available `Allocator` is [`Global`](https://doc.rust-lang.org/1.75.0/alloc/alloc/struct.Global.html), which delegates to the registered `GlobalAlloc`. Since `GlobalAlloc::realloc()` [cannot change the required alignment](https://doc.rust-lang.org/1.75.0/core/alloc/trait.GlobalAlloc.html#method.realloc), the implementation of [`<Global as Allocator>::shrink()`](https://github.com/rust-lang/rust/blob/db7125f008cfd72e8951c9a863178956e2cbacc3/library/alloc/src/alloc.rs#L280-L321) must fall back to creating a brand-new allocation, `memcpy`ing the data into it, and freeing the old allocation, whenever the alignment doesn't remain exactly the same.
>
> Therefore, the underlying allocator, provided by libc or some other source, has no opportunity to internally `mremap()` the data when the alignment is changed, since it has no way of knowing that the allocation is the same.

…albertlarsan68

Increase vscode settings.json `git.detectSubmodulesLimit`

The default vscode git integration throws a warning on the rust repository because it has more than the default limit of 10 submodules. This adds an increase to 20 to the settings.json that x.py offers to install on setup.

<img width="461" alt="Screen Shot 2024-01-19 at 11 47 47 PM" src="https://github.com/rust-lang/rust/assets/230691/440dfa4e-32e3-41f7-b8c6-5a07ade7aa14">

Also reported at https://stackoverflow.com/questions/60917209/disable-vs-code-warning-submodules-which-wont-be-opened-automatically

Spelling fix

"It's" expands to "it is". "It is use..." doesn't make sense.

"Its" is the possessive form, and the intended form here.