Provide optional `Read`/`Write` methods for stdio
Override more of the default methods for `io::Read` and `io::Write` for stdio types, when efficient to do so, and deduplicate unsupported types.
Tracked in https://github.com/rust-lang/rust/issues/136756.
try-job: x86_64-msvc-1
core: optimize `RepeatN`
...by adding an optimized implementation of `try_fold` and `fold` as well as replacing some unnecessary `mem::replace` calls with `MaybeUninit` helper methods.
Mark some std tests as requiring `panic = "unwind"`
This allows these test modules to pass on builds/targets without unwinding support, where `panic = "abort"` - the ignored tests are for functionality that's not supported on those targets.
...by adding an optimized implementation of `try_fold` and `fold` as well as replacing some unnecessary `mem::replace` calls with `MaybeUninit` helper methods.
As per #117276, this moves the implementations of `Process` and friends out of the `pal` module and into the `sys` module, removing quite a lot of error-prone `#[path]` imports in the process (hah, get it ;-)). I've also made the `zircon` module a dedicated submodule of `pal::unix`, hopefully we can move some other definitions there as well (they are currently quite a lot of duplications in `sys`). Also, the `ensure_no_nuls` function on Windows now lives in `sys::pal::windows` – it's not specific to processes and shared by the argument implementation.
Add stack overflow handler for cygwin
The cygwin runtime handles stack overflow exception and converts it to `SIGSEGV`, but the passed `si_addr` is obtained from `ExceptionInformation[1]` which is actually an undocumented value when stack overflows. Thus I choose to use Windows API directly to register handler, just like how std does on native Windows. The code is basically copied from the Windows one.
Ref:
* 5ec497dc80/winsup/cygwin/exceptions.cc (L822-L823)
* https://learn.microsoft.com/zh-cn/windows/win32/api/winnt/ns-winnt-exception_record
Reduce FormattingOptions to 64 bits
This is part of https://github.com/rust-lang/rust/issues/99012
This reduces FormattingOptions from 6-7 machine words (384 bits on 64-bit platforms, 224 bits on 32-bit platforms) to just 64 bits (a single register on 64-bit platforms).
Before:
```rust
pub struct FormattingOptions {
flags: u32, // only 6 bits used
fill: char,
align: Option<Alignment>,
width: Option<usize>,
precision: Option<usize>,
}
```
After:
```rust
pub struct FormattingOptions {
/// Bits:
/// - 0-20: fill character (21 bits, a full `char`)
/// - 21: `+` flag
/// - 22: `-` flag
/// - 23: `#` flag
/// - 24: `0` flag
/// - 25: `x?` flag
/// - 26: `X?` flag
/// - 27: Width flag (if set, the width field below is used)
/// - 28: Precision flag (if set, the precision field below is used)
/// - 29-30: Alignment (0: Left, 1: Right, 2: Center, 3: Unknown)
/// - 31: Always set to 1
flags: u32,
/// Width if width flag above is set. Otherwise, always 0.
width: u16,
/// Precision if precision flag above is set. Otherwise, always 0.
precision: u16,
}
```
Match what `std::io::Empty` does, since it is very similar. However,
still evaluate the `fmt::Arguments` in `write_fmt` to be consistent with
other platforms.
Add an attribute that makes the spans from a macro edition 2021, and fix pin on edition 2024 with it
Fixes a regression, see issue below. This is a temporary fix, super let is the real solution.
Closes#138596
This commit adds the 5f00::/16 range defined by RFC9602 to those ranges which Ipv6Addr::is_global recognises as a non-global IP. This range is used for Segment Routing (SRv6) SIDs.
Optimize `io::Write::write_fmt` for constant strings
When the formatting args to `fmt::Write::write_fmt` are a statically known string, it simplifies to only calling `write_str` without a runtime branch. Do the same in `io::Write::write_fmt` with `write_all`.
Also, match the convention of `fmt::Write` for the name of `args`.
Document results of non-positive logarithms
The integer versions of logarithm functions panic on non-positive numbers. The floating point versions have different, undocumented behaviour (-inf on 0, NaN on <0). This PR documents that.
try-job: aarch64-gnu
The default stack size for the main thread is 1 MB as specified by linker options.
However, the default stack size for threads was only 64 kB.
This is surprisingly small and thus we increase it to 1 MB to match the
main thread.
Implement default methods for `io::Empty` and `io::Sink`
Implements default methods of `io::Read`, `io::BufRead`, and `io::Write` for `io::Empty` and `io::Sink`. These implementations are equivalent to the defaults, except in doing less unnecessary work.
`Read::read_to_string` and `BufRead::read_line` both have a redundant call to `str::from_utf8` which can't be inlined from `core` and `Write::write_all_vectored` has slicing logic which can't be simplified (See on [Compiler Explorer](https://rust.godbolt.org/z/KK6xcrWr4)). The rest are optimized to the minimal with `-C opt-level=3`, but this PR gives that benefit to unoptimized builds.
This includes an implementation of `Write::write_fmt` which just ignores the `fmt::Arguments<'_>`. This could be problematic whenever a user formatting impl is impure, but the docs do not guarantee that the args will be expanded.
Tracked in https://github.com/rust-lang/rust/issues/136756.
r? `@m-ou-se`
`MaybeUninit` inherent slice methods part 2
These were moved out of #129259 since they require additional libs-api approval. Tracking issue: #117428.
New API surface:
```rust
impl<T> [MaybeUninit<T>] {
// replacing fill; renamed to avoid conflict
pub fn write_filled(&mut self, value: T) -> &mut [T] where T: Clone;
// replacing fill_with; renamed to avoid conflict
pub fn write_with<F>(&mut self, value: F) -> &mut [T] where F: FnMut() -> T;
// renamed to remove "fill" terminology, since this is closer to the write_*_of_slice methods
pub fn write_iter<I>(&mut self, iter: I) -> (&mut [T], &mut Self) where I: Iterator<Item = T>;
}
```
Relevant motivation for these methods; see #129259 for earlier methods' motiviations.
* I chose `write_filled` since `filled` is being used as an object here, whereas it's being used as an action in `fill`.
* I chose `write_with` instead of `write_filled_with` since it's shorter and still matches well.
* I chose `write_iter` because it feels completely different from the fill methods, and still has the intent clear.
In all of the methods, it felt appropriate to ensure that they contained `write` to clarify that they are effectively just special ways of doing `MaybeUninit::write` for each element of a slice.
Tracking issue: https://github.com/rust-lang/rust/issues/117428
r? libs-api
Revert: Add *_value methods to proc_macro lib
This reverts https://github.com/rust-lang/rust/pull/136355. That PR caused unexpected breakage:
- the rustc-dev component can no longer be loaded by cargo, which impacts Miri and clippy and likely others
- rustc_lexer can no longer be published to crates.io, which impacts RA
See https://github.com/rust-lang/rust/issues/138647 for context.
Cc `@GuillaumeGomez` `@Amanieu`
