To aid making an informed decision about the aliasing
rules of box, give users an option to remove `noalias`
from box.

stdlib support for Apple WatchOS

This is a follow-up to rust-lang#95243 (Add Apple WatchOS compiler targets) that adds stdlib support for Apple WatchOS.

`@deg4uss3r`
`@nagisa`

…r=oli-obk

Do not allow typeck children items to constrain outer RPITs

Fixes rust-lang#99073 in a simpler and more conservative way than rust-lang#99079. Simply raise a mismatched types error if we try to constrain an RPIT in an item that isn't the RPIT's parent.

r? `@oli-obk`

Formalize defining_use_anchor

This tackles issue rust-lang#57961

Introduces new enum called `DefiningAnchor` that replaces `Option<LocalDefId>` of `defining_use_anchor`. Now every use of it is explicit and exhaustively matched, catching errors like one in the linked issue. This is not a perfect fix but it's a step in the right direction.

r? `@oli-obk`

…1-dead

Add flag to configure `noalias` on `Box<T>`

The aliasing rules of `Box<T>` are still not decided, but currently, `Box<T>` is unique and gets `noalias`. To aid making an informed decision about the future of `Box<T>`, this PR adds a flag `-Zbox-noalias` to configure `noalias` for `Box<T>` (for example, for benchmarking). The same flag already exists for `&mut T` `noalias`, where it was added because it was the problem of various miscompilations in LLVM.

For more information, see rust-lang/unsafe-code-guidelines#326

Fix a numerical underflow in tuple wrap suggestion

Fixes rust-lang#99482

I'm a clown, I rewrote the arg mismatch algo to use well-typed indices to avoid things like this, but then I added my own indexing bug, lol.

…-derive, r=oli-obk

Stop injecting `#[allow(unused_qualifications)]` in generated `derive` implementations

Currently, the `#[derive]` attribute always injects an `#[allow(unused_qualifications)]` attribute in the generated implementation. This results in an error when a derive is used in combination with `#![forbid(unused_qualifications)]`, because the `forbid` rule by definition cannot be overridden by `allow`.

It appears that the original issue that prompted the inclusion of `#[allow(unused_qualifications)]` (rust-lang#19102) is no longer present in the current stable release, and the associated [test case](https://github.com/rust-lang/rust/blob/master/src/test/ui/issues/issue-19102.rs) still passes, so the `allow` is simply removed here.

Fixes rust-lang#71898.

…on-in-check-str-addition, r=compiler-errors

Refactor: remove a string comparison between types in `check_str_addition`

This patch removes remove a string of types comparison.