Add vectored positioned I/O on Unix
Add methods for vectored I/O with an offset on `File` for `unix` under `#![feature(unix_file_vectored_at)]`.
The new methods are wrappers around `preadv` and `pwritev`.
Tracking issue: #89517
Match unmatched backticks in library/
Found with GNU grep:
```
grep -rEn '^(([^`]*`){2})*[^`]*`[^`]*$' library/ | rg -v '\s*[//]?.{1,2}```'
```
split out from #108685 as per advice.
Add `Atomic*::from_ptr`
This PR adds functions in the following form to all atomic types:
```rust
impl AtomicT {
pub const unsafe fn from_ptr<'a>(ptr: *mut T) -> &'a AtomicT;
}
```
r? `@m-ou-se` (we've talked about it before)
I'm not sure about docs & safety requirements, I'd appreciate some feedback on them.
Add support for QNX Neutrino to standard library
This change:
- adds standard library support for QNX Neutrino (7.1).
- upgrades `libc` to version `0.2.139` which supports QNX Neutrino
`@gh-tr`
⚠️ Backtraces on QNX require https://github.com/rust-lang/backtrace-rs/pull/507 which is not yet merged! (But everything else works without these changes) ⚠️
Tested mainly with a x86_64 virtual machine (see qnx-nto.md) and partially with an aarch64 hardware (some tests fail due to constrained resources).
Merge two different equality specialization traits in `core`
Arrays and slices each had their own version of this, without a matching set of `impl`s.
Merge them into one (still-`pub(crate)`) `cmp::BytewiseEq` trait, so we can stop doing all these things twice.
And that means that the `[T]::eq` → `memcmp` specialization picks up a bunch of types where that previously only worked for arrays, so examples like <https://rust.godbolt.org/z/KjsG8MGGT> will use it now instead of emitting loops.
r? the8472
Add `Option::as_`(`mut_`)`slice`
This adds the following functions:
* `Option<T>::as_slice(&self) -> &[T]`
* `Option<T>::as_mut_slice(&mut self) -> &[T]`
The `as_slice` and `as_mut_slice_mut` functions benefit from an optimization that makes them completely branch-free. ~~Unfortunately, this optimization is not available on by-value Options, therefore the `into_slice` implementations use the plain `match` + `slice::from_ref` approach.~~
Note that the optimization's soundness hinges on the fact that either the niche optimization makes the offset of the `Some(_)` contents zero or the mempory layout of `Option<T>` is equal to that of `Option<MaybeUninit<T>>`.
The idea has been discussed on [Zulip](https://rust-lang.zulipchat.com/#narrow/stream/219381-t-libs/topic/Option.3A.3Aas_slice). Notably the idea for the `as_slice_mut` and `into_slice´ methods came from `@cuviper` and `@Sp00ph` hardened the optimization against niche-optimized Options.
The [rust playground](https://play.rust-lang.org/?version=nightly&mode=release&edition=2021&gist=74f8e4239a19f454c183aaf7b4a969e0) shows that the generated assembly of the optimized method is basically only a copy while the naive method generates code containing a `test dx, dx` on x86_64.
---
EDIT from reviewer: ACP is https://github.com/rust-lang/libs-team/issues/150
Remove or document uses of #[rustc_box] in library
r? `@thomcc`
Only one of these uses is tested for in the rustc-perf benchmark suite. The impact there on compile time is somewhat dramatic, but I am inclined to make this change as a simplification to the library and wait for people to complain if it explodes their compilation time. I think in the absence of data or reports from users about what code paths really matter, if we are optimizing for compilation time, it's hard to argue against using `#[rustc_box]` everywhere we currently call `Box::new`.
add missing feature in core/tests
https://github.com/rust-lang/rust/pull/104265 introduced the `ip_in_core` feature. For some reason core tests seem to still build without that feature -- no idea how that is possible. Might be related to https://github.com/rust-lang/rust/issues/15702? I was under the impression that `pub use` with different stability doesn't actually work. That's why `intrinsics::transmute` is stable, for example.
Either way, core tests fail to build in miri-test-libstd, and adding the feature fixes that.
r? ```@thomcc```
This adds the following functions:
* `Option<T>::as_slice(&self) -> &[T]`
* `Option<T>::as_slice_mut(&mut self) -> &[T]`
The `as_slice` and `as_slice_mut` functions benefit from an
optimization that makes them completely branch-free.
Note that the optimization's soundness hinges on the fact that either
the niche optimization makes the offset of the `Some(_)` contents zero
or the mempory layout of `Option<T>` is equal to that of
`Option<MaybeUninit<T>>`.
Inline `Poll` methods
With `opt-level="z"`, the `Poll::map*` methods are sometimes not inlined (see <https://godbolt.org/z/ca5ajKTEK>). This PR adds `#[inline]` to these methods. I have a project that can benefit from this change, but do we want to enable this behavior universally?
Fixes#101080.
Stabilize `#![feature(target_feature_11)]`
## Stabilization report
### Summary
Allows for safe functions to be marked with `#[target_feature]` attributes.
Functions marked with `#[target_feature]` are generally considered as unsafe functions: they are unsafe to call, cannot be assigned to safe function pointers, and don't implement the `Fn*` traits.
However, calling them from other `#[target_feature]` functions with a superset of features is safe.
```rust
// Demonstration function
#[target_feature(enable = "avx2")]
fn avx2() {}
fn foo() {
// Calling `avx2` here is unsafe, as we must ensure
// that AVX is available first.
unsafe {
avx2();
}
}
#[target_feature(enable = "avx2")]
fn bar() {
// Calling `avx2` here is safe.
avx2();
}
```
### Test cases
Tests for this feature can be found in [`src/test/ui/rfcs/rfc-2396-target_feature-11/`](b67ba9ba20/src/test/ui/rfcs/rfc-2396-target_feature-11/).
### Edge cases
- https://github.com/rust-lang/rust/issues/73631
Closures defined inside functions marked with `#[target_feature]` inherit the target features of their parent function. They can still be assigned to safe function pointers and implement the appropriate `Fn*` traits.
```rust
#[target_feature(enable = "avx2")]
fn qux() {
let my_closure = || avx2(); // this call to `avx2` is safe
let f: fn() = my_closure;
}
```
This means that in order to call a function with `#[target_feature]`, you must show that the target-feature is available while the function executes *and* for as long as whatever may escape from that function lives.
### Documentation
- Reference: https://github.com/rust-lang/reference/pull/1181
---
cc tracking issue #69098
r? `@ghost`
[stdio][windows] Use MBTWC and WCTMB
`MultiByteToWideChar` and `WideCharToMultiByte` are extremely well optimized, and therefore should probably be used when we know we can (specifically in the Windows stdio stuff).
Fixes#107092
Move IpAddr, SocketAddr and V4+V6 related types to `core`
Implements RFC https://github.com/rust-lang/rfcs/pull/2832. The RFC has completed FCP with disposition merge, but is not yet merged.
Moves IP types to `core` as specified in the RFC.
The full list of moved types is: `IpAddr`, `Ipv4Addr`, `Ipv6Addr`, `SocketAddr`, `SocketAddrV4`, `SocketAddrV6`, `Ipv6MulticastScope` and `AddrParseError`.
Doing this move was one of the main driving arguments behind #78802.
Remove `from` lang item
It was probably a leftover from the old `?` desugaring but anyways, it's unused now except for clippy, which can just use a diagnostics item.
Fix `VecDeque::shrink_to` and add tests.
Fixes#108453.
Also adds both a specific test with the code from #108453 and an exhaustive test that checks all possible head positions, lengths and target capacities for deques with capacity 16.
cc `@trinity-1686a` `@scottmcm`
Require `literal`s for some `(u)int_impl!` parameters
The point of these is to be seen *lexically* in the docs, so they should always be passed as the correct literal, not as an expression.
(Otherwise we could just compute `Min`/`Max` from `BITS`, for example.)
r? Nilstrieb
This adds both a test specific to #108453 as well as an exhaustive test
that goes through all possible combinations of head index, length and target capacity
for a deque with capacity 16.
add support of RustyHermit's BSD socket layer
RustyHermit is a tier 3 platform and publishes a new kernel interface. The new version supports a common BSD socket layer. By supporting this interface, the implementation of `std` can be harmonized to other operating systems. In `sys_common/mod.rs` we remove only a special case for RustyHermit. All changes are done in the RustyHermit specific directories.
To realize this socket layer, the handling of file descriptors is also harmonized to other operating systems.
