rust-lang / rust

…-obk

Disable the SimplifyArmIdentity mir-opt

The optimization still has some bugs that need to be worked out
such as #77359.

We can try re-enabling this again after the known issues are resolved.

r? `@oli-obk`

Add accessors to Command.

This adds some accessor methods to `Command` to provide a way to access the values set when building the `Command`. An example where this can be useful is to display the command to be executed. This is roughly based on the [`ProcessBuilder`](https://github.com/rust-lang/cargo/blob/13b73cdaf76b2d9182515c9cf26a8f68342d08ef/src/cargo/util/process_builder.rs#L105-L134) in Cargo.

Possible concerns about the API:
- Values with NULs on Unix will be returned as `"<string-with-nul>"`. I don't think it is practical to avoid this, since otherwise a whole separate copy of all the values would need to be kept in `Command`.
- Does not handle `arg0` on Unix. This can be awkward to support in `get_args` and is rarely used. I figure if someone really wants it, it can be added to `CommandExt` as a separate method.
- Does not offer a way to detect `env_clear`. I'm uncertain if it would be useful for anyone.
- Does not offer a way to get an environment variable by name (`get_env`). I figure this can be added later if anyone really wants it. I think the motivation for this is weak, though. Also, the API could be a little awkward (return a `Option<Option<&OsStr>>`?).
- `get_envs` could skip "cleared" entries and just return `&OsStr` values instead of `Option<&OsStr>`. I'm on the fence here. My use case is to display a shell command, and I only intend it to be roughly equivalent to the actual execution, and I probably won't display `None` entries. I erred on the side of providing extra information, but I suspect many situations will just filter out the `None`s.
- Could implement more iterator stuff (like `DoubleEndedIterator`).

I have not implemented new std items before, so I'm uncertain if the existing issue should be reused, or if a new tracking issue is needed.

cc #44434

Rollup of 11 pull requests

Successful merges:

 - #76851 (Fix 'FIXME' about using NonZeroU32 instead of u32.)
 - #76979 (Improve std::sys::windows::compat)
 - #77111 (Stabilize slice_ptr_range.)
 - #77147 (Split sys_common::Mutex in StaticMutex and MovableMutex.)
 - #77312 (Remove outdated line from `publish_toolstate` hook)
 - #77362 (Fix is_absolute on WASI)
 - #77375 (rustc_metadata: Do not forget to encode inherent impls for foreign types)
 - #77385 (Improve the example for ptr::copy)
 - #77389 (Fix some clippy lints)
 - #77399 (BTreeMap: use Unique::from to avoid a cast where type information exists)
 - #77429 (Link `new` method in `DefautHasher`s doc)

Failed merges:

r? `@ghost`

The optimization still has some bugs that need to be worked out
such as #77359.

We can try re-enabling this again after the known issues are resolved.

…jyn514

Link `new` method in `DefautHasher`s doc

FIXME referenced #56922 which was resolved

r? @jyn514

BTreeMap: use Unique::from to avoid a cast where type information exists

r? @Mark-Simulacrum

Fix some clippy lints

Found while working on #77351;
these are just the ones that could be fixed automatically.

Improve the example for ptr::copy

Fixes #77220

rustc_metadata: Do not forget to encode inherent impls for foreign types

So I tried to move FFI interface for LLVM from `rustc_codegen_llvm` to `rustc_llvm` and immediately encountered this fascinating issue.

Fixes #46665.

Fix is_absolute on WASI

WASI does not match `cfg(unix)`, but its paths are Unix-like (`/some/path`) and don't have Windows-like prefixes.

Without this change, `is_absolute` for any paths, including `/some/path`, was returning `false`on a WASI target, which is obviously not true and undesirable.

…crum

Remove outdated line from `publish_toolstate` hook

We no longer add `I-nominated` to toolstate failure issues since T-compiler changed its meeting preparation workflow.

…lnay

Split sys_common::Mutex in StaticMutex and MovableMutex.

The (unsafe) `Mutex` from `sys_common` had a rather complicated interface. You were supposed to call `init()` manually, unless you could guarantee it was neither moved nor used reentrantly.

Calling `destroy()` was also optional, although it was unclear if 1) resources might be leaked or not, and 2) if `destroy()` should only be called when `init()` was called.

This allowed for a number of interesting (confusing?) different ways to use this `Mutex`, all captured in a single type.

In practice, this type was only ever used in two ways:

1. As a static variable. In this case, neither `init()` nor `destroy()` are called. The variable is never moved, and it is never used reentrantly. It is only ever locked using the `LockGuard`, never with `raw_lock`.

2. As a `Box`ed variable. In this case, both `init()` and `destroy()` are called, it will be moved and possibly used reentrantly.

No other combinations are used anywhere in `std`.

This change simplifies things by splitting this `Mutex` type into two types matching the two use cases: `StaticMutex` and `MovableMutex`.

The interface of both new types is now both safer and simpler. The first one does not call nor expose `init`/`destroy`, and the second one calls those automatically in its `new()` and `Drop` functions. Also, the locking functions of `MovableMutex` are no longer unsafe.

---

This will also make it easier to conditionally box mutexes later, by moving that decision into sys/sys_common. Some of the mutex implementations (at least those of Wasm and 'sys/unsupported') are safe to move, so wouldn't need a box. ~~(But that's blocked on  #76932 for now.)~~ (See #77380.)

…-range, r=dtolnay

Stabilize slice_ptr_range.

This has been unstable for almost a year now. Time to stabilize?

Closes #65807.

@rustbot modify labels: +T-libs +A-raw-pointers +A-slice +needs-fcp

…eck, r=dtolnay

Improve std::sys::windows::compat

Improves the compat_fn macro in sys::windows, which is used for conditionally loading APIs that might not be available.

- The module (dll) name can now be any string, not just an ident. (Not all Windows api modules are valid Rust identifiers. E.g. `WaitOnAddress` comes from `API-MS-Win-Core-Synch-l1-2-0.dll`.)
- Adds `FuncName::is_available()` for checking if a function is really available without having to do a duplicate lookup.
- Add comment explaining the lack of locking.
- Use `$_:block` to simplify the macro_rules.
- Apply `allow(unused_variables)` only to the fallback instead of everything.

---

The second point (`is_available()`) simplifies code that needs to pick an implementation depening on what is available, like `sys/windows/mutex.rs`. Before this change, it'd do its own lookup and keep its own `AtomicUsize` to track the result. Now it can just use `c::AcquireSRWLockExclusive::is_available()` directly.

This will also be useful when park/unpark/CondVar/etc. get improved implementations (e.g. from parking_lot or something else), as the best APIs for those are not available before Windows 8.

…trochenkov

Fix 'FIXME' about using NonZeroU32 instead of u32.

It was blocked by #58732 (const fn NonZeroU32::new), which is fixed now.

Update rls

Includes rust-lang/rls#1700, just fixing compilation and test failures.

Fixes #77311.

Refactor memchr to allow optimization

Closes #75659

The implementation already uses naive search if the slice if short enough, but the case is complicated enough to not be optimized away. This PR refactors memchr so that it exists early when the slice is short enough.

Codegen-wise, as shown in #75659, memchr was not inlined previously so the only way I could find to test this is to check if there is no memchr call. Let me know if there is a more robust solution here.

* rust-lang/rls#1700

Make RawFd implement the RawFd traits

This PR makes `RawFd` implement `AsRawFd`, `IntoRawFd` and `FromRawFd`, so it can be passed to interfaces that use one of those traits as a bound.

Co-authored-by: David Tolnay <[email protected]>

- Module name can now be any string, not just an ident.
  (Not all Windows api modules are valid Rust identifiers.)
- Adds c::FuncName::is_available() for checking if a function is really
  available without having to do a duplicate lookup.
- Add comment explaining the lack of locking.
- Use `$_:block` to simplify the macro_rules.
- Apply allow(unused_variables) only to the fallback instead of
  everything.

Use futex-based thread::park/unpark on Linux.

This moves the parking/unparking logic out of `thread/mod.rs` into a module named `thread_parker` in `sys_common`. The current implementation is moved to `sys_common/thread_parker/generic.rs` and the new implementation using futexes is added in `sys_common/thread_parker/futex.rs`.

Implement multiple return terminator optimization

Closes #72022

…li-obk

Overhaul const-checking diagnostics

The primary purpose of this PR was to remove `NonConstOp::STOPS_CONST_CHECKING`, which causes any additional errors found by the const-checker to be silenced. I used this flag to preserve diagnostic parity with `qualify_min_const_fn.rs`, which has since been removed.

However, simply removing the flag caused a deluge of errors in some cases, since an error would be emitted any time a local or temporary had a wrong type. To remedy this, I added an alternative system (`DiagnosticImportance`) to silence additional error messages that were likely to distract the user from the underlying issue. When an error of the highest importance occurs, all less important errors are silenced. When no error of the highest importance occurs, all less important errors are emitted after checking is complete. Following the suggestions from the important error is usually enough to fix the less important errors, so this should lead to better UX most of the time.

There's also some unrelated diagnostics improvements in this PR isolated in their own commits. Splitting them out would be possible, but a bit of a pain. This isn't as tidy as some of my other PRs, but it should *only* affect diagnostics, never whether or not something passes const-checking. Note that there are a few trivial exceptions to this, like banning `Yield` in all const-contexts, not just `const fn`.

As always, meant to be reviewed commit-by-commit.

r? `@oli-obk`