glibc destroys[1] the passed pthread_attr_t if pthread_getattr_np()
fails.  Destroying it again leads to a segfault.  Fix it by only
destroying it on success for glibc.

[1]: https://sourceware.org/git/?p=glibc.git;a=blob;f=nptl/pthread_getattr_np.c;h=ce437205e41dc05653e435f6188768cccdd91c99;hb=HEAD#l205

…ibcs

The calling convention of pthread_getattr_np() is to initialize the
pthread_attr_t, so _destroy() is only necessary on success (and _init()
isn't necessary beforehand).  On the other hand, FreeBSD wants the
attr_t to be initialized before pthread_attr_get_np(), and therefore it
should always be destroyed afterwards.

A significant amount of intrinsics do not actually need backend-specific
behaviors to be implemented, instead relying on methods already in
rustc_codegen_ssa. So, extract those methods out to rustc_codegen_ssa,
so that each backend doesn't need to reimplement the same code.

Previously, `x.py` would unconditionally run `x.py build` to get the
help message. After rust-lang#76165,
when checking the CI stage was moved into `Config`, that would cause an
assertion failure (but only only in CI!):

```
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `1`,
 right: `2`', src/bootstrap/config.rs:619:49
```

This changes bootstrap to only generate a help message when it needs
to (when someone passes `--help`).

Use `SyncOnceCell` to only compile it once.
I believe this still adds some kind of locking mechanism?

The use of arith_offset was added in 803e9ae
before the stable wrapper of the intrinsic was available.

https://doc.rust-lang.org/stable/std/intrinsics/fn.arith_offset.html

The latter is on the path to stabilization.

… length (clippy::manual_strip)

Co-authored-by: est31 <est31@users.noreply.github.com>

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

…roy, r=Amanieu

Fix segfault if pthread_getattr_np fails

glibc [destroys][1] the passed pthread_attr_t if pthread_getattr_np()
fails.  Destroying it again leads to a segfault.  Fix it by only
destroying it on success for glibc.

[1]: https://sourceware.org/git/?p=glibc.git;a=blob;f=nptl/pthread_getattr_np.c;h=ce437205e41dc05653e435f6188768cccdd91c99;hb=HEAD#l205

…ulacrum

Test and fix Send and Sync traits of BTreeMap artefacts

Fixes rust-lang#76686.

I'm not quite sure what all this implies. E.g. comparing with the definitions for `NodeRef` in node.rs,  maybe an extra bound `T: 'a` is useful for something. The test compiles on stable/beta (apart from `drain_filter`) so I bet `Sync` is equally desirable.

r? @Mark-Simulacrum

Extract some intrinsics out of rustc_codegen_llvm

A significant amount of intrinsics do not actually need backend-specific behaviors to be implemented, instead relying on methods already in rustc_codegen_ssa. So, extract those methods out to rustc_codegen_ssa, so that each backend doesn't need to reimplement the same code.

Almost everything should be a pretty direct translation. A notable not-direct-translation is `add_with_overflow` and friends being changed to `bx.checked_binop`, but it's pretty simple.

I could have been a lot more aggressive here and pulled out way more methods, and add a few new methods in the rustc_codegen_ssa "API". However, because this is my second rustc PR, I thought that moving those to a follow-up PR and doing more incremental changes here would be better (and I guess ask if this work is even desired in the first place). I'm hoping to eventually remove the mess of intrinsic handling in the backend entirely, which would be hecking fantastic ✨

Only get ImplKind::Impl once

With this, the code panics in one place instead of two.

Don't generate bootstrap usage unless it's needed

Previously, `x.py` would unconditionally run `x.py build` to get the
help message. After rust-lang#76165,
when checking the CI stage was moved into `Config`, that would cause an
assertion failure (but only only in CI!):

```
thread 'main' panicked at 'assertion failed: `(left == right)`
  left: `1`,
 right: `2`', src/bootstrap/config.rs:619:49
```

This changes bootstrap to only generate a help message when it needs
to (when someone passes `--help`).

r? @Mark-Simulacrum
This should fix the CI failures in rust-lang#76797 and rust-lang#75991.

simplfy condition in ItemLowerer::with_trait_impl_ref()

Fix wording in mir doc

…me, r=ecstatic-morse

Don't compile regex at every function call.

Use `SyncOnceCell` to only compile it once.
I believe this still adds some kind of locking mechanism?

Related issue: rust-lang#76817

…ures, r=oli-obk,Mark-Simulacrum

Remove redundant nightly features

Removes a bunch of redundant/outdated nightly features. The first commit removes a `core_intrinsics` use for which a stable wrapper has been provided since. The second commit replaces the `const_generics` feature with `min_const_generics` which might get stabilized this year. The third commit is the result of a trial/error run of removing every single feature and then adding it back if compile failed. A bunch of unused features are the result that the third commit removes.

…lett

black_box: silence unused_mut warning when building with cfg(miri)

use `array_windows` instead of `windows` in the compiler

I do think these changes are beautiful, but do have to admit that using type inference for the window length
can easily be confusing. This seems like a general issue with const generics, where inferring constants adds an additional
complexity which users have to learn and keep in mind.

…hievink

fix array_windows docs

r? @Dylan-DPC

…=lcnr

use strip_prefix over starts_with and manual slicing based on pattern length (clippy::manual_strip)

…d-future, r=jyn514

Move to intra doc links in core/src/future

Helps with rust-lang#75080.

@rustbot modify labels: T-doc A-intra-doc-links

r? @jyn514

…c-morse

Let user see the full type of type-length limit error

Seeing the full type of the error is sometimes essential to diagnosing the problem, but the type itself is too long to be displayed in the terminal in a useful fashion. This change solves this dilemma by writing the full offending type name to a file, and displays this filename as a note.

> note: the full type name been written to '$TEST_BUILD_DIR/issues/issue-22638/issue-22638.long-type.txt'

Closes rust-lang#76777