Rollup of 5 pull requests

Successful merges:

 - #71165 (`slice::fill`: use `T` instead of generic arg)
 - #71314 (Implement RFC 2523, `#[cfg(version(..))]`)
 - #71542 (Implement `confusable_idents` lint.)
 - #71806 (typo)
 - #71813 (Decode qualifs for associated const defaults)

Failed merges:

r? @ghost

Decode qualifs for associated const defaults

Fixes #71734.

We encode qualifs for associated constants, but never expected to decode the qualifs for defaulted associated consts. Fix this, and test that associated const defaults have the correct qualifs cross-crate.

r? @tmandry

typo

Implement `confusable_idents` lint.

This collects all identifier symbols into `ParseSession` and examines them within the non-ascii-idents lint.

The skeleton generation part needs to be added to `unicode-security` crate. Will update this PR when the crate is updated.

r? @petrochenkov

EDIT: also included the `concat_idents` part.

Implement RFC 2523, `#[cfg(version(..))]`

Hi! This is my first contribution to rust, I hope I didn't miss anything. I tried to implement this feature so that `#[cfg(version(1.44.0))]` works but the parser was printing an error that I wasn't sure how to fix so I just opted for implementing `#[cfg(version("1.44.0"))]` (note the quotes).

Tracking issue: #64796

`slice::fill`: use `T` instead of generic arg

implements https://github.com/rust-lang/rust/issues/70758#issuecomment-613994427

As the discussion in #70758 has shifted, I now use `T` instead of `&T`.

Don't bust caches on x.py check/build switches

Fixes #71152

Rollup of 7 pull requests

Successful merges:

 - #69274 (Implement RFC 2396: `#[target_feature]` 1.1)
 - #71767 (doc: make Stack and StackElement a little pretty)
 - #71772 (Mark query function as must_use.)
 - #71777 (cleanup: `config::CrateType` -> `CrateType`)
 - #71784 (Remove recommendation for unmaintained dirs crate)
 - #71785 (Update comment regarding SO_REUSEADDR on Windows)
 - #71787 (fix rustdoc warnings)

Failed merges:

r? @ghost

The extracted function can be used by the rest of bootstrap to detect if we've
already built an up-to-date LLVM (and so it's safe for us to either request it
or pretend it exists).

This also tests for the ICE in #71734

Implement RFC 2396: `#[target_feature]` 1.1

Tracking issue: #69098

r? @nikomatsakis
cc @gnzlbg @joshtriplett

fix rustdoc warnings

Update comment regarding SO_REUSEADDR on Windows

Remove recommendation for unmaintained dirs crate

See #71684 for reasoning here

cleanup: `config::CrateType` -> `CrateType`

Mark query function as must_use.

And use the `ensure()` version when the result is not needed.

doc: make Stack and StackElement a little pretty

Also, fix rustdoc warnings.

Implement RFC 2396: `#[target_feature]` 1.1

Tracking issue: #69098

r? @nikomatsakis
cc @gnzlbg @joshtriplett

update Miri

This contains the concurrency support by @vakaras :)

Fixes https://github.com/rust-lang/rust/issues/71729
r? @ghost
Cc @rust-lang/miri

Make clippy a git subtree instead of a git submodule

r? @EddyB

cc #70651

documentation at https://github.com/rust-lang/rust/pull/70654

Rollup of 6 pull requests

Successful merges:

 - #71712 (Miri: port error backtraces to std::backtrace)
 - #71736 (bootstrap: also apply unused-attributes hack without deny_warnings)
 - #71738 (remove AllocId generalization of Pointer)
 - #71739 (remove obsolete comment)
 - #71781 (Uncomment test code for failure to use `Box::pin`)
 - #71782 (Use a non-existent test path instead of clobbering /dev/null)

Failed merges:

r? @ghost

Use a non-existent test path instead of clobbering /dev/null

Fixes #71502.
r? @Mark-Simulacrum

Uncomment test code for failure to use `Box::pin`

Close #69083.

remove obsolete comment

Referenced was removed in 9f492fef

remove AllocId generalization of Pointer

This was only needed for the "snapshot" machinery, which is gone.

r? @oli-obk

bootstrap: also apply unused-attributes hack without deny_warnings

This is a follow-up to https://github.com/rust-lang/rust/pull/70881 that also silences these warnings when deny_warnings is off. They otherwise spam my screen during development and make it hard to see actual warnings.

Cc  @EddyB r? @Mark-Simulacrum

Miri: port error backtraces to std::backtrace

No need to pull in an external dependency if libstd already includes this feature (using the same dependency internally, but... still).

r? @oli-obk