…in traits

Rayon's `try_for_each` makes the `CombinedEncoder` a lot simpler.

Previously, we were running bare commands for `ToolBuild` step and
were unable to utilize some of the flags which  are already handled by
`compile::stream_cargo`.

This change makes `ToolBuild` to use `compile::stream_cargo`, allowing us
to benefit from the flags supported by the bootstrap cargo.

Signed-off-by: onur-ozkan <work@onurozkan.dev>

Stabilise `c_unwind`

Fix rust-lang#74990
Fix rust-lang#115285 (that's also where FCP is happening)

Marking as draft PR for now due to `compiler_builtins` issues

r? ``@Amanieu``

…rntSushi

Stabilize `binary_heap_as_slice`

This PR stabilizes `binary_heap_as_slice`:

```rust
// std::collections::BinaryHeap

impl BinaryHeap<T> {
    pub fn as_slice(&self) -> &[T]
}
```

<br>

Tracking issue: rust-lang#83659.
Implementation PR: rust-lang#82331.

FCPs already completed in the tracking issue.

Closes rust-lang#83659.

r? libs-api

…r=michaelwoerister

Parse unsafe attributes

Initial parse implementation for rust-lang#123757

This is the initial work to parse unsafe attributes, which is represented as an extra `unsafety` field in `MetaItem` and `AttrItem`. There's two areas in the code where it appears that parsing is done manually and not using the parser stuff, and I'm not sure how I'm supposed to thread the change there.

…nkfelix

Detect pub structs never constructed and unused associated constants

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Lints never constructed public structs.

If we don't provide public methods to construct public structs with private fields, and don't construct them in the local crate. They would be never constructed. So that we can detect such public structs.

---
Update:

Also lints unused associated constants in traits.

…=albertlarsan68

prefer `compile::stream_cargo` for building tools

Previously, we were running bare commands for `ToolBuild` step and were unable to utilize some of the flags which  are already handled by `compile::stream_cargo`.

This change makes `ToolBuild` to use `compile::stream_cargo`, allowing us to benefit from the flags supported by the bootstrap cargo.

Resolves rust-lang#125666

…r=Mark-Simulacrum

Update `./x fmt` command in library/std/src/sys/pal/windows/c/README.md

`./x fmt` no longer accepts paths so the command in the readme won't work.

…albertlarsan68

Simplify the rayon calls in the installer

Rayon's `try_for_each` makes the `CombinedEncoder` a lot simpler.

Stabilize Option::take_if

Closes rust-lang#98934

ed: FCP complete in rust-lang#98934 (comment)

…ouxu

Clean up source root in run-make tests

The name `S` isn't exactly the most descriptive, and we also shouldn't need to pass it when building (actually I think that most of the env. vars that we pass to `cargo` here are probably not really needed).

Related issue: rust-lang#126071

r? ``@jieyouxu``

Improve docs for using custom paths with `--emit`

Recently I found myself concluding that this feature didn't exist (rust-lang#126111 (comment)), despite having read the documentation, because it was hidden away in the middle of a paragraph full of other information.

Giving this documentation more space of its own should make it easier to find.