Stabilize slice_partition_at_index
This stabilizes slice_partition_at_index, including renaming `partition_at_index*` -> `select_nth_unstable*`.
Closes#55300
r? `@Amanieu`
Implement `AsRawFd` for `StdinLock` etc. on WASI.
WASI implements `AsRawFd` for `Stdin`, `Stdout`, and `Stderr`, so
implement it for `StdinLock`, `StdoutLock`, and `StderrLock` as well.
r? @alexcrichton
The stabilisation issue, #73413, has an open item for documentation.
I looked at the docs and it is all there, but I felt it could do with
some minor wording improvement.
I looked at the `str::strip_prefix` docs for a template. (That
resulted in me slightly changing that doc too.)
I de-linkified `None` and `Some`, as I felt that rather noisy.. I
searched stdlib, and these don't seem to be usually linkified.
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
"Some is returned with <some value>" is an awkward construction.
The use of the passive voice is a bit odd, and doesn't seem like the
house style.
So say instead "returns X, wrapped in `Some`", for which there is some
other precedent in stdlib.
Instead of repeating "with the prefix removed", say "after the
prefix". This is a bit clearer that the original is not modified.
Signed-off-by: Ian Jackson <ijackson@chiark.greenend.org.uk>
This stabilizes the functionality in slice_partition_at_index,
but under the names `select_nth_unstable*`. The functions
`partition_at_index*` are left as deprecated, to be removed in
a later release.
Closes#55300
Avoid SeqCst or static mut in mach_timebase_info and QueryPerformanceFrequency caches
This patch went through a couple iterations but the end result is replacing a pattern where an `AtomicUsize` (updated with many SeqCst ops) guards a `static mut` with a single `AtomicU64` that is known to use 0 as a value indicating that it is not initialized.
The code in both places exists to cache values used in the conversion of Instants to Durations on macOS, iOS, and Windows.
I have no numbers to prove that this improves performance (It seems a little futile to benchmark something like this), but it's much simpler, safer, and in practice we'd expect it to be faster everywhere where Relaxed operations on AtomicU64 are cheaper than SeqCst operations on AtomicUsize, which is a lot of places.
Anyway, it also removes a bunch of unsafe code and greatly simplifies the logic, so IMO that alone would be worth it unless it was a regression.
If you want to take a look at the assembly output though, see https://godbolt.org/z/rbr6vn for x86_64, https://godbolt.org/z/cqcbqv for aarch64 (Note that this just the output of the mac side, but i'd expect the windows part to be the same and don't feel like doing another godbolt for it). There are several versions of this function in the godbolt:
- `info_new`: version in the current patch
- `info_less_new`: version in initial PR
- `info_original`: version currently in the tree
- `info_orig_but_better_orderings`: a version that just tries to change the original code's orderings from SeqCst to the (probably) minimal orderings required for soundness/correctness.
The biggest concern I have here is if we can use AtomicU64, or if there are targets that dont have it that this code supports. AFAICT: no. (If that changes in the future, it's easy enough to do something different for them)
r? `@Amanieu` because he caught a couple issues last time I tried to do a patch reducing orderings 😅
---
<details>
<summary>I rewrote this whole message so the original is inside here</summary>
I happened to notice the code we use for caching the result of mach_timebase_info uses SeqCst exclusively.
However, thinking a little more, it's actually pretty easy to avoid the static mut by packing the timebase info into an AtomicU64.
This entirely avoids needing to do the compare_exchange. The AtomicU64 can be read/written using Relaxed ops, which on current macos/ios platforms (x86_64/aarch64) have no overhead compared to direct loads/stores. This simplifies the code and makes it a lot safer too.
I have no numbers to prove that this improves performance (It seems a little futile to benchmark something like this), although it should do that on both targets it applies to.
That said, it also removes a bunch of unsafe code and simplifies the logic (arguably at least — there are only two states now, initialized or not), so I think it's a net win even without concrete numbers.
If you want to take a look at the assembly output though, see below. It has the new version, the original, and a version of the original with lower Orderings (which is still worse than the version in this PR)
- godbolt.org/z/obfqf9 x86_64-apple-darwin
- godbolt.org/z/Wz5cWc aarch64-unknown-linux-gnu (godbolt can't do aarch64-apple-ios but that doesn't matter here)
A different (and more efficient) option than this would be to just use the AtomicU64 and use the knowledge that after initialization the denominator should be nonzero... That felt like it's relying on too many things I'm not confident in, so I didn't want to do that.
</details>
rust-lang/rust#77147 simplifies things by splitting this Mutex type
into two types matching the two use cases: StaticMutex and MovableMutex.
To support the behavior of StaticMutex, we move part of the mutex
implementation into libstd.
Allow generic parameters in intra-doc links
Fixes#62834.
---
The contents of the generics will be mostly ignored (except for warning
if fully-qualified syntax is used, which is currently unsupported in
intra-doc links - see issue #74563).
* Allow links like `Vec<T>`, `Result<T, E>`, and `Option<Box<T>>`
* Allow links like `Vec::<T>::new()`
* Warn on
* Unbalanced angle brackets (e.g. `Vec<T` or `Vec<T>>`)
* Missing type to apply generics to (`<T>` or `<Box<T>>`)
* Use of fully-qualified syntax (`<Vec as IntoIterator>::into_iter`)
* Invalid path separator (`Vec:<T>:new`)
* Too many angle brackets (`Vec<<T>>`)
* Empty angle brackets (`Vec<>`)
Note that this implementation *does* allow some constructs that aren't
valid in the actual Rust syntax, for example `Box::<T>new()`. That may
not be supported in rustdoc in the future; it is an implementation
detail.
doc: disambiguate stat in MetadataExt::as_raw_stat
A few architectures in `os::linux::raw` import `libc::stat`, rather than
defining that type directly. However, that also imports the _function_
called `stat`, which makes this doc link ambiguous:
error: `crate::os::linux::raw::stat` is both a struct and a function
--> library/std/src/os/linux/fs.rs:21:19
|
21 | /// [`stat`]: crate::os::linux::raw::stat
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ ambiguous link
|
= note: `-D broken-intra-doc-links` implied by `-D warnings`
help: to link to the struct, prefix with the item type
|
21 | /// [`stat`]: struct@crate::os::linux::raw::stat
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
help: to link to the function, add parentheses
|
21 | /// [`stat`]: crate::os::linux::raw::stat()
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
We want the `struct`, so it's now prefixed accordingly.
fix __rust_alloc_error_handler comment
`__rust_alloc_error_handler` was added in the same `extern` block as the allocator functions, but the comment there was not actually correct for `__rust_alloc_error_handler`. So move it down to the rest of the default allocator handling with a fixed comment. At least the comment reflects my understanding of what happens, please check carefully. :)
r? @Amanieu Cc @haraldh
