…or std/thread

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.

Make the following methods unstable const under the `const_pin` feature:
- `new`
- `new_unchecked`
- `into_inner`
- `into_inner_unchecked`
- `get_ref`
- `into_ref`

Also adds tests for these methods in a const context.

Tracking issue: rust-lang#76654

Only insert StorageDeads if we actually removed one.
Fixes an issue where we added StorageDead to a place with no StorageLive

This is heavily dependent on MIR inlining running to actually see the drop statement

Co-authored-by: Andreas Jonson <andjo403@users.noreply.github.com>

`const_mut_refs` doesn't actually work in a `const` or `static`

Otherwise, we may not have a standard library built for the native "host" target
of the rustc being run.

This isn't an issue for most folks who use x.py dist, which will directly depend
on this. But for x.py build, if we don't properly set target here rustdoc will
not be built.

Currently, there is not a default-on step for generating a rustc for a given
target either, so we will fail to build a rustc as well.

Make the following methods unstable const under the `const_pin` feature:
- `into_ref`
- `get_mut`
- `get_unchecked_mut`

Latter is simpler

Update the tracking issue number

Updated the documentation for `UnsafeCell`

Address review comments

Address more review comments + minor changes

- Allow including defaults in `src/bootstrap/defaults` using `profile = "..."`
- Add default config files
- Combine config files using the merge dependency.
- Add comments to default config files
- Add a README asking to open an issue if the defaults are bad
- Give a loud error if trying to merge `.target`, since it's not
  currently supported
- Use an exhaustive match
- Use `<none>` in config.toml.example to avoid confusion
- Fix bugs in `Merge` derives

Previously, it would completely ignore the profile defaults if there
were any settings in `config.toml`. I sent an email to the `merge` maintainer
asking them to make the behavior in this commit the default.

This introduces a new dependency on `merge` that hasn't yet been vetted.

I want to improve the output when `include = "x"` isn't found:

```
thread 'main' panicked at 'fs::read_to_string(&file) failed with No such file or directory (os error 2) ("configuration file did not exist")', src/bootstrap/config.rs:522:28
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
failed to run: /home/joshua/rustc/build/bootstrap/debug/bootstrap test tidy
Build completed unsuccessfully in 0:00:00
```

However that seems like it could be fixed in a follow-up.

…n-unsafe-fn, r=joshtriplett

Std/thread: deny unsafe op in unsafe fn

Partial fix of rust-lang#73904.

This encloses `unsafe` operations in `unsafe fn` in `libstd/thread`.
@rustbot modify labels: F-unsafe-block-in-unsafe-fn

…Kalbertodt

Avoid useless sift_down when std::collections::binary_heap::PeekMut is never mutably dereferenced

If `deref_mut` is never called then it's not possible for the element to be mutated without internal mutability, meaning there's no need to call `sift_down`.

This could be a little improvement in cases where you want to mutate the biggest element of the heap only if it satisfies a certain predicate that needs only read access to the element.

…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

do not ICE on bound variables, return `TooGeneric` instead

fixes rust-lang#73260, fixes rust-lang#74634, fixes rust-lang#76595

r? @nikomatsakis

…-Simulacrum

Add sample defaults for config.toml

- Allow including defaults in `src/bootstrap/defaults` using `profile = "..."`.
- Add default config files, with a README noting they're experimental and asking you to open an issue if you run into trouble. The config files have comments explaining why the defaults are set.
- Combine config files using the `merge` dependency.

This introduces a new dependency on `merge` that hasn't yet been vetted.

I want to improve the output when `include = "x"` isn't found:

```
thread 'main' panicked at 'fs::read_to_string(&file) failed with No such file or directory (os error 2) ("configuration file did not exist")', src/bootstrap/config.rs:522:28
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
failed to run: /home/joshua/rustc/build/bootstrap/debug/bootstrap test tidy
Build completed unsuccessfully in 0:00:00
```

However that seems like it could be fixed in a follow-up.

Closes rust-lang#76619

Make some methods of `Pin` unstable const

Make the following methods unstable const under the `const_pin` feature:
- `new`
- `new_unchecked`
- `into_inner`
- `into_inner_unchecked`
- `get_ref`
- `into_ref`
- `get_mut`
- `get_unchecked_mut`

Of these, `into_inner` and `into_inner_unchecked` require the unstable `const_precise_live_drops`.

Also adds tests for these methods in a const context.

Tracking issue: rust-lang#76654

r? @ecstatic-morse

SimplifyComparisonIntegral: fix miscompilation

Fixes rust-lang#76432
Only insert StorageDeads if we actually removed one.
Fixes an issue where we added StorageDead to a place with no StorageLive

r? @oli-obk

…r=oli-obk

MIR pass to remove unneeded drops on types not needing drop

This is heavily dependent on MIR inlining running to actually see the drop statement.

Do we want to special case replacing a call to std::mem::drop with a goto aswell?

Only get ImplKind::Impl once

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

…ist, r=alexcrichton

Fix cross compiling dist/build invocations

I am uncertain why the first commit is not affecting CI. I suspect it's because we pass --disable-docs on most of our cross-compilation builders. The second commit doesn't affect CI because CI runs x.py dist, not x.py build.

Both commits are standalone; together they should resolve rust-lang#76733. The first commit doesn't really fix that issue but rather just fixes cross-compiled x.py dist, resolving a bug introduced in rust-lang#76549.

…d-api, r=oli-obk

Use const-checking to forbid use of unstable features in const-stable functions

First step towards rust-lang#76618.

Currently this code isn't ever hit because `qualify_min_const_fn` runs first and catches pretty much everything. One exception is `const_precise_live_drops`, which does not use the newly added code since it runs as part of a separate pass.

Also contains some unrelated refactoring, which is split into separate commits.

r? @oli-obk

Avoiding unnecesary allocations at rustc_errors

Simplify the code avoiding allocations with easy alternative

…=jyn514

Use intra-doc links in core/src/iter when possible

Helps with rust-lang#75080.

I also updated lots of links to use `fn()` instead of `fn` when possible.

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

r? @jyn514

…jyn514

Finish moving to intra doc links for std::sync

Helps with rust-lang#75080.

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

r? @jyn514

…mut, r=RalfJung

Add non-`unsafe` `.get_mut()` for `Unsafecell`

  - Tracking issue: rust-lang#76943

As discussed in: https://internals.rust-lang.org/t/add-non-unsafe-get-mut-for-unsafecell/12407

  - ### [Rendered documentation](https://modest-dubinsky-1f9f47.netlify.app/core/cell/struct.unsafecell)

This PR tries to move the sound `&mut UnsafeCell<T> -> &mut T` projection that all the "downstream" constructions were already relying on, up to the root abstraction, where it rightfully belongs, and officially blessing it.

  - this **helps reduce the amount of `unsafe` snippets out there** (_c.f._, the second commit of this PR: rust-lang@09503fd)

The fact that this getter is now expose for `UnsafeCell<T>` itself, will also help convey the idea that **`UnsafeCell` is not magical _w.r.t._ `&mut` accesses**, contrary to what some people incorrectly think.

  - Even the standard library itself at some point had such a confusion, _c.f._ this comment where there is a mention of multi-threaded (and thus _shared_) access despite dealing with exclusive references over unique ownership: https://github.com/rust-lang/rust/blob/59fb88d061544a035f3043b47594b34789204cee/library/core/src/cell.rs#L498-L499

r? @RalfJung

Replace manual as_nanos and as_secs_f64 reimplementations

Replace write_fmt with write!

Latter is simpler