Insta-stabilize the methods `is_ready` and `is_pending` of `Poll`.

Possible because of the recent stabilization of const control flow.

Also adds a test for these methods in a const context.

Part of rust-lang#76268

POSIX leaves it implementation-defined whether `link` follows symlinks.
In practice, for example, on Linux it does not and on FreeBSD it does.
So, switch to `linkat`, so that we can pick a behavior rather than
depending on OS defaults.

Pick the option to not follow symlinks. This is somewhat arbitrary, but
seems the less surprising choice because hard linking is a very
low-level feature which requires the source and destination to be on
the same mounted filesystem, and following a symbolic link could end
up in a different mounted filesystem.

Due to the recent release of 1.47.0, this PR will be stabilized in 1.49.0 instead of 1.48.0.

Also mention that where possible, `hard_link` does not follow symlinks.

According to [the bionic status page], `linkat` has only been available
since API level 21. Since Android is based on Linux and Linux's `link`
doesn't follow symlinks, just use `link` on Android.

[the bionic status page]: https://android.googlesource.com/platform/bionic/+/master/docs/status.md

Co-authored-by: Ashley Mannix <kodraus@hey.com>

Co-authored-by: Ashley Mannix <kodraus@hey.com>

Co-authored-by: Ashley Mannix <kodraus@hey.com>

This adds a binary called `x` in `src/tools/x`. All it does is check the
current directory and its ancestors for a file called `x.py`, and if it
finds one, runs it.

By installing x, you can easily `x.py` from any subdirectory.

It can be installed globally with `cargo install --path src/tools/x`

This also adds a note about missing stack probes support, per the
discussion on RFC 2959.

Previously, trying to allow this would give another error!

```
warning: unknown lint: `private_intra_doc_links`
 --> private.rs:1:10
  |
1 | #![allow(private_intra_doc_links)]
  |          ^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean: `broken_intra_doc_links`
  |
  = note: `#[warn(unknown_lints)]` on by default

warning: public documentation for `DocMe` links to private item `DontDocMe`
 --> private.rs:2:11
  |
2 | /// docs [DontDocMe]
  |           ^^^^^^^^^ this item is private
  |
  = note: `#[warn(private_intra_doc_links)]` on by default
  = note: this link will resolve properly if you pass `--document-private-items`
```

This is really starting to get out of hand. Rustdoc should instead allow
all lints in the rustdoc lint group.

This is the Rust side of rust-lang/wg-cargo-std-aware#23

Partially fix rust-lang#55002, deprecate in another release

Co-authored-by: Ashley Mannix <kodraus@hey.com>

Update stable version for stabilize_spin_loop

Co-authored-by: Joshua Nelson <joshua@yottadb.com>

Use better example for spinlock

As suggested by KodrAus

Remove renamed_spin_loop already available in master

Fix spin loop example

- Handle variants, fields, macros in `Node::ident()`
- Handle the crate root in `opt_item_name`
- Factor out `item_name_from_def_id` to reduce duplication
- Look at HIR before the DefId for `opt_item_name`

  This gives accurate spans, which are not available from serialized
  metadata.

- Don't panic on the crate root in `opt_item_name`
- Add comments

…rAus

Stabilize hint::spin_loop

Partially fix rust-lang#55002, deprecate in another release

r? `````@KodrAus`````

Stabilize `Poll::is_ready` and `is_pending` as const

Insta-stabilize the methods `is_ready` and `is_pending` of `std::task::Poll` as const, in the same way as [PR#76198](rust-lang#76198).

Possible because of the recent stabilization of const control flow.

Part of rust-lang#76225.

…t_2, r=KodrAus

Refactor IntErrorKind to avoid "underflow" terminology

This PR is a continuation of rust-lang#76455

# Changes

- `Overflow` renamed to `PosOverflow` and `Underflow` renamed to `NegOverflow` after discussion in rust-lang#76455
- Changed some of the parsing code to return `InvalidDigit` rather than `Empty` for strings "+" and "-". https://users.rust-lang.org/t/misleading-error-in-str-parse-for-int-types/49178
- Carry the problem `char` with the `InvalidDigit` variant.
- Necessary changes were made to the compiler as it depends on `int_error_matching`.
- Redid tests to match on specific errors.

r? `@KodrAus`

…olnay

Define `fs::hard_link` to not follow symlinks.

POSIX leaves it [implementation-defined] whether `link` follows symlinks.
In practice, for example, on Linux it does not and on FreeBSD it does.
So, switch to `linkat`, so that we can pick a behavior rather than
depending on OS defaults.

Pick the option to not follow symlinks. This is somewhat arbitrary, but
seems the less surprising choice because hard linking is a very
low-level feature which requires the source and destination to be on
the same mounted filesystem, and following a symbolic link could end
up in a different mounted filesystem.

[implementation-defined]: https://pubs.opengroup.org/onlinepubs/9699919799/functions/link.html

make concurrency helper more pleasant to read

Recognize `private_intra_doc_links` as a lint

Previously, trying to allow this would give another error!

```
warning: unknown lint: `private_intra_doc_links`
 --> private.rs:1:10
  |
1 | #![allow(private_intra_doc_links)]
  |          ^^^^^^^^^^^^^^^^^^^^^^^ help: did you mean: `broken_intra_doc_links`
  |
  = note: `#[warn(unknown_lints)]` on by default

warning: public documentation for `DocMe` links to private item `DontDocMe`
 --> private.rs:2:11
  |
2 | /// docs [DontDocMe]
  |           ^^^^^^^^^ this item is private
  |
  = note: `#[warn(private_intra_doc_links)]` on by default
  = note: this link will resolve properly if you pass `--document-private-items`
```

Fixes the issue found in rust-lang#77249 (comment).

r? ``````@Manishearth``````

Does anyone know why this additional step is necessary? It seems weird this has to be declared in 3 different places.

…crum

Promote aarch64-unknown-linux-gnu to Tier 1

This PR promotes the `aarch64-unknown-linux-gnu` target to Tier 1, as proposed by [RFC 2959]:

* The `aarch64-gnu` CI job is moved from `auto-fallible` to `auto`.
* The platform support documentation is updated, uplifting the target to Tiert 1 with a note about missing stack probes support.
* Building the documentation is enabled for the target, as we produce the `rust-docs` component for all Tier 1 platforms.

[RFC 2959]: rust-lang/rfcs#2959

Fix handling of item names for HIR

- Handle variants, fields, macros in `Node::ident()`
- Handle the crate root in `opt_item_name`
- Rewrite `item_name` in terms of `opt_item_name`

I need this for both rust-lang#77820 and rust-lang#78082, so splitting it out into a separate PR so it can land early.

… r=Mark-Simulacrum

BTreeMap: stop mistaking node for an orderly place

A second mistake in rust-lang#77612 was to ignore the node module's rightful comment "this module doesn't care whether the entries are sorted". And there's a much simpler way to visit the keys in order, if you check this separately from a single pass checking everything.

r? ``````@Mark-Simulacrum``````

…crum

fix some incorrect aliasing in the BTree

This line is wrong:
```
ptr::copy(slice.as_ptr().add(idx), slice.as_mut_ptr().add(idx + 1), slice.len() - idx);
```
When `slice.as_mut_ptr()` is called, that creates a mutable reference to the entire slice, which invalidates the raw pointer previously returned by `slice.as_ptr()`. (Miri currently misses this because raw pointers are not tracked properly.)

Cc ``````@ssomers``````

…-size, r=jyn514

Remove FIXME comment in print_type_sizes ui test suite

## Overview
Helps with rust-lang#62277

> The type sizes are likely only printed when the actual layout is computed. For generic types, this only happens during codegen.

ref: https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/Codegen.20process.20question/near/215836807

Some tests like `multiple_types.rs` are passed even if using `check-pass`. But tests should be agnostic to when the actual layout is computed. The `build-pass` is intentionally used for them. I remove FIXME comments.

Add a tool to run `x.py` from any subdirectory

This adds a binary called `x` in `src/tools/x`. All it does is check the current directory and its ancestors for a file called `x.py`, and if it finds one, runs it.

By installing x, you can easily run `x.py` from any subdirectory, and only need to type `x`.

It can be installed with `cargo install --path src/tools/x`

This is a copy of a [binary I've been using myself when working on rust](https://github.com/casey/bootstrap), currently published to crates.io as `bootstrap`.

It could be changed to avoid indirecting through `x.py`, and instead call the bootstrap module directly. However, this seemed like the simplest thing possible, and won't break if the details of how the bootstrap module is invoked change.

…=Mark-Simulacrum

Fix run-make tests running when LLVM is disabled

The `--cc`, `--cxx`, `--cflags` and `--ar` flags were only passed to compiletest when `builder.config.llvm_enabled()` returned true. This is preventing me from running the tests on cg_clif.

…lacrum

Vendor libtest's dependencies in the rust-src component

This is the Rust side of rust-lang/wg-cargo-std-aware#23

Note that this won't produce a useful result for `cargo -Zbuild-std` if there are multiple versions of a crate vendored, but will otherwise produce a valid vendor dir.

See rust-lang/cargo#8834 for the other half of this change.

use single char patterns for split() (clippy::single_char_pattern)