Make more `From` impls `const` (libcore)
Adding `const` to `From` implementations in the core. `rustc_const_unstable` attribute is not added to unstable implementations.
Tracking issue: #88674
<details>
<summary>Done</summary><div>
- `T` from `T`
- `T` from `!`
- `Option<T>` from `T`
- `Option<&T>` from `&Option<T>`
- `Option<&mut T>` from `&mut Option<T>`
- `Cell<T>` from `T`
- `RefCell<T>` from `T`
- `UnsafeCell<T>` from `T`
- `OnceCell<T>` from `T`
- `Poll<T>` from `T`
- `u32` from `char`
- `u64` from `char`
- `u128` from `char`
- `char` from `u8`
- `AtomicBool` from `bool`
- `AtomicPtr<T>` from `*mut T`
- `AtomicI(bits)` from `i(bits)`
- `AtomicU(bits)` from `u(bits)`
- `i(bits)` from `NonZeroI(bits)`
- `u(bits)` from `NonZeroU(bits)`
- `NonNull<T>` from `Unique<T>`
- `NonNull<T>` from `&T`
- `NonNull<T>` from `&mut T`
- `Unique<T>` from `&mut T`
- `Infallible` from `!`
- `TryIntError` from `!`
- `TryIntError` from `Infallible`
- `TryFromSliceError` from `Infallible`
- `FromResidual for Option<T>`
</div></details>
<details>
<summary>Remaining</summary><dev>
- `NonZero` from `NonZero`
These can't be made const at this time because these use Into::into.
https://github.com/rust-lang/rust/blob/master/library/core/src/convert/num.rs#L393
- `std`, `alloc`
There may still be many implementations that can be made `const`.
</div></details>
remove unnecessary bound on Zip specialization impl
I originally added this bound in an attempt to make the specialization
sound for owning iterators but it was never correct here and the correct
and [already implemented](497ee321af/library/alloc/src/vec/into_iter.rs (L220-L232)) solution is is to place it on the IntoIter
implementation.
Alloc features cleanup
This sorts and categorizes the `#![features]` in `alloc` and removes unused ones.
This is part of #87766
The following feature attributes were unnecessary and are removed:
```diff
// Library features:
-#![feature(cow_is_borrowed)]
-#![feature(maybe_uninit_uninit_array)]
-#![feature(slice_partition_dedup)]
// Language features:
-#![feature(arbitrary_self_types)]
-#![feature(auto_traits)]
-#![feature(box_patterns)]
-#![feature(decl_macro)]
-#![feature(nll)]
```
Automatic exponential formatting in Debug
Context: See [this comment from the libs team](https://github.com/rust-lang/rfcs/pull/2729#issuecomment-853454204)
---
Makes `"{:?}"` switch to exponential for floats based on magnitude. The libs team suggested exploring this idea in the discussion thread for RFC rust-lang/rfcs#2729. (**note:** this is **not** an implementation of the RFC; it is an implementation of one of the alternatives)
Thresholds chosen were 1e-4 and 1e16. Justification described [here](https://github.com/rust-lang/rfcs/pull/2729#issuecomment-864482954).
**This will require a crater run.**
---
As mentioned in the commit message of 8731d4dfb4, this behavior will not apply when a precision is supplied, because I wanted to preserve the following existing and useful behavior of `{:.PREC?}` (which recursively applies `{:.PREC}` to floats in a struct):
```rust
assert_eq!(
format!("{:.2?}", [100.0, 0.000004]),
"[100.00, 0.00]",
)
```
I looked around and am not sure where there are any tests that actually use this in the test suite, though?
All things considered, I'm surprised that this change did not seem to break even a single existing test in `x.py test --stage 2`. (even when I tried a smaller threshold of 1e6)
Rollup of 8 pull requests
Successful merges:
- #89766 (RustWrapper: adapt for an LLVM API change)
- #89867 (Fix macro_rules! duplication when reexported in the same module)
- #89941 (removing TLS support in x86_64-unknown-none-hermitkernel)
- #89956 (Suggest a case insensitive match name regardless of levenshtein distance)
- #89988 (Do not promote values with const drop that need to be dropped)
- #89997 (Add test for issue #84957 - `str.as_bytes()` in a `const` expression)
- #90002 (⬆️ rust-analyzer)
- #90034 (Tiny tweak to Iterator::unzip() doc comment example.)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
Tiny tweak to Iterator::unzip() doc comment example.
It's easier to figure out what it's doing and which output elements map to which input ones if the matrix we are dealing with is rectangular 2x3 rather than square 2x2.
removing TLS support in x86_64-unknown-none-hermitkernel
HermitCore's kernel itself doesn't support TLS. Consequently, the entries in x86_64-unknown-none-hermitkernel should be removed. This commit should help to finalize #89062.
Revert "Auto merge of #89709 - clemenswasser:apply_clippy_suggestions…
…_2, r=petrochenkov"
The PR had some unforseen perf regressions that are not as easy to find.
Revert the PR for now.
This reverts commit 6ae8912a3e, reversing
changes made to 86d6d2b738.
It's easier to figure out what it's doing and which output
elements map to which input ones if the matrix we are dealing
with is rectangular 2x3 rather than square 2x2.
Remove a mention to `copy_from_slice` from `clone_from_slice` doc
Fixes#84736
I think removing it would be the best but I'm happy to clarify it instead if someone would like.
linux/aarch64 Now() should be actually_monotonic()
While issues have been seen on arm64 platforms the Arm architecture requires
that the counter monotonically increases and that it must provide a uniform
view of system time (e.g. it must not be possible for a core to receive a
message from another core with a time stamp and observe time going backwards
(ARM DDI 0487G.b D11.1.2). While there have been a few 64bit SoCs that have
bugs (#49281, #56940) which cause time to not monotonically increase, these have
been fixed in the Linux kernel and we shouldn't penalize all Arm SoCs for those
who refuse to update their kernels:
SUN50I_ERRATUM_UNKNOWN1 - Allwinner A64 / Pine A64 - fixed in 5.1
FSL_ERRATUM_A008585 - Freescale LS2080A/LS1043A - fixed in 4.10
HISILICON_ERRATUM_161010101 - Hisilicon 1610 - fixed in 4.11
ARM64_ERRATUM_858921 - Cortex A73 - fixed in 4.12
255a3f3e18 std: Force `Instant::now()` to be monotonic added a Mutex to work around
this problem and a small test program using glommio shows the majority of time spent
acquiring and releasing this Mutex. 3914a7b0da tries to improve this, but actually
makes it worse on big systems as for 128b atomics a ldxp/stxp pair (and successful loop)
for v8.4 systems that don't support FEAT_LSE2 is required which is expensive as a lock
and because of how the load/store-exclusives scale on large Arm systems is both unfair
to threads and tends to go backwards in performance.
A small sample program using glommio improves by 70x on a 32 core Graviton2
system with this change.
Add `#[repr(i8)]` to `Ordering`
Followup to #89491 to allow `Ordering` to auto-derive `AsRepr` once the proposal to add `AsRepr` (#81642) lands.
cc ``@joshtriplett``
updating docs to mention usage of AtomicBool
Mouse mentioned we should point out that atomic bool is used by the std lib these days. ( https://github.com/m-ou-se/getrandom/pull/1 )
[fuchsia] Update process info struct
The fuchsia platform is in the process of softly transitioning over to
using a new value for ZX_INFO_PROCESS with a new corresponding struct.
This change migrates libstd.
See [fxrev.dev/510478](https://fxrev.dev/510478) and [fxbug.dev/30751](https://fxbug.dev/30751) for more detail.
Stabilize `unreachable_unchecked` as `const fn`
Closes#53188
This PR stabilizes `core::hint::unreachable_unchecked` as `const fn`. MIRI is able to detect when this method is called. Stabilization was delayed until `const_panic` was stabilized so as to avoid users calling this method in its place (thus resulting in runtime UB). With #89508, that is no longer an issue.
````@rustbot```` label +A-const-eval +A-const-fn +T-lang +S-blocked
(not sure why it's T-lang, but that's what the tracking issue is)
Add abstract namespace support for Unix domain sockets
Hello! The other day I wanted to mess around with UDS in Rust and found that abstract namespaces ([unix(7)](https://man7.org/linux/man-pages/man7/unix.7.html)) on Linux still needed development. I took the approach of adding `_addr` specific public functions to reduce conflicts.
Feature name: `unix_socket_abstract`
Tracking issue: #85410
Further context: #42048
## Non-platform specific additions
`UnixListener::bind_addr(&SocketAddr) -> Result<UnixListener>`
`UnixStream::connect_addr(&SocketAddr) -> Result<()>`
`UnixDatagram::bind_addr(&SocketAddr) -> Result<UnixDatagram>`
`UnixDatagram::connect_addr(&SocketAddr) -> Result<()>`
`UnixDatagram::send_to_addr(&self, &[u8], &SocketAddr) -> Result<usize>`
## Platform-specific (Linux) additions
`SocketAddr::from_abstract_namespace(&[u8]) -> SocketAddr`
`SockerAddr::as_abstract_namespace() -> Option<&[u8]>`
## Example
```rust
#![feature(unix_socket_abstract)]
use std::os::unix::net::{UnixListener, SocketAddr};
fn main() -> std::io::Result<()> {
let addr = SocketAddr::from_abstract_namespace(b"namespace")?; // Linux only
let listener = match UnixListener::bind_addr(&addr) {
Ok(sock) => sock,
Err(err) => {
println!("Couldn't bind: {:?}", err);
return Err(err);
}
};
Ok(())
}
```
## Further Details
The main inspiration for the implementation came from the [nix-rust](https://github.com/nix-rust/nix/blob/master/src/sys/socket/addr.rs#L558) crate but there are also other [historical](c4db0685b1) [attempts](https://github.com/tormol/uds/blob/master/src/addr.rs#L324) with similar approaches.
A comment I did have was with this change, we now allow a `SocketAddr` to be constructed explicitly rather than just used almost as a handle for the return of `peer_addr` and `local_addr`. We could consider adding other explicit constructors (e.g. `SocketAddr::from_pathname`, `SockerAddr::from_unnamed`).
Cheers!
Use BCryptGenRandom instead of RtlGenRandom on Windows.
This removes usage of RtlGenRandom on Windows, in favour of BCryptGenRandom.
BCryptGenRandom isn't available on XP, but we dropped XP support a while ago.
The fuchsia platform is in the process of softly transitioning over to
using a new value for ZX_INFO_PROCESS with a new corresponding struct.
This change migrates libstd.
See fxrev.dev/510478 and fxbug.dev/30751 for more detail.
Avoid allocations and copying in Vec::leak
The [`Vec::leak`] method (#62195) is currently implemented by calling `Vec::into_boxed_slice` and `Box::leak`. This shrinks the vector before leaking it, which potentially causes a reallocation and copies the vector's contents.
By avoiding the conversion to `Box`, we can instead leak the vector without any expensive operations, just by returning a slice reference and forgetting the `Vec`. Users who *want* to shrink the vector first can still do so by calling `shrink_to_fit` explicitly.
**Note:** This could break code that uses `Box::from_raw` to “un-leak” the slice returned by `Vec::leak`. However, the `Vec::leak` docs explicitly forbid this, so such code is already incorrect.
[`Vec::leak`]: https://doc.rust-lang.org/stable/std/vec/struct.Vec.html#method.leak
Optimize VecDeque::append
Optimize `VecDeque::append` to do unsafe copy rather than iterating through each element.
On my `Intel(R) Xeon(R) CPU E5-2630 v4 @ 2.20GHz`, the benchmark shows 37% improvements:
```
Master:
custom-bench vec_deque_append 583164 ns/iter
custom-bench vec_deque_append 550040 ns/iter
Patched:
custom-bench vec_deque_append 349204 ns/iter
custom-bench vec_deque_append 368164 ns/iter
```
Additional notes on the context: this is the third attempt to implement a non-trivial version of `VecDeque::append`, the last two are reverted due to unsoundness or regression, see:
- https://github.com/rust-lang/rust/pull/52553, reverted in https://github.com/rust-lang/rust/pull/53571
- https://github.com/rust-lang/rust/pull/53564, reverted in https://github.com/rust-lang/rust/pull/54851
Both cases are covered by existing tests.
Signed-off-by: tabokie <xy.tao@outlook.com>
The PR had some unforseen perf regressions that are not as easy to find.
Revert the PR for now.
This reverts commit 6ae8912a3e, reversing
changes made to 86d6d2b738.
Fix ctrl-c causing reads of stdin to return empty on Windows.
Pressing ctrl+c (or ctrl+break) on Windows caused a blocking read of stdin to unblock and return empty, unlike other platforms which continue to block.
On ctrl-c, `ReadConsoleW` will return success, but also set `LastError` to `ERROR_OPERATION_ABORTED`.
This change detects this case, and re-tries the call to `ReadConsoleW`.
Fixes#89177. See issue for further details.
Tested on Windows 7 and Windows 10 with both MSVC and GNU toolchains
Add `const_eval_select` intrinsic
Adds an intrinsic that calls a given function when evaluated at compiler time, but generates a call to another function when called at runtime.
See https://github.com/rust-lang/const-eval/issues/7 for previous discussion.
r? `@oli-obk.`
