The current code will not results bug, but it difficult to understand. These code result to call &f32::partial_cmp(), and the performance will be lower than the changed code. I'm not sure why the current code don't use (*self) (*other), if you have some idea, please let me know.
update docs for `std::future::IntoFuture`
Ref https://github.com/rust-lang/rust/issues/67644.
This updates the docs for `IntoFuture` providing a bit more guidance on how to use it. Thanks!
Add the Provider api to core::any
This is an implementation of [RFC 3192](https://github.com/rust-lang/rfcs/pull/3192) ~~(which is yet to be merged, thus why this is a draft PR)~~. It adds an API for type-driven requests and provision of data from trait objects. A primary use case is for the `Error` trait, though that is not implemented in this PR. The only major difference to the RFC is that the functionality is added to the `any` module, rather than being in a sibling `provide_any` module (as discussed in the RFC thread).
~~Still todo: improve documentation on items, including adding examples.~~
cc `@yaahc`
This commit adds a new unstable attribute, `#[doc(tuple_varadic)]`, that
shows a 1-tuple as `(T, ...)` instead of just `(T,)`, and links to a section
in the tuple primitive docs that talks about these.
Suggest using `iter()` or `into_iter()` for `Vec`
We cannot do that for `&Vec` because `#[rustc_on_unimplemented]` is limited (it does not clean generic instantiation for references, only for ADTs).
`@rustbot` label +A-diagnostics
Use repr(C) when depending on struct layout in ptr tests
The test depends on the layout of this struct `Pair`, so it should use `repr(C)` instead of the default `repr(Rust)`.
Improve the safety docs for `CStr`
Namely, the two functions `from_ptr` and `from_bytes_with_nul_unchecked`.
Before, these functions didn't state the requirements clearly enough,
and I was not immediately able to find them like for other functions.
This doesn't change the content of the docs, but simply rewords them for
clarity.
note: I'm not entirely sure about the '`ptr` must be valid for reads of `u8`.', there might be room for improvement for this (and maybe for the other docs as well 😄)
Namely, the two functions `from_ptr` and `from_bytes_with_nul_unchecked`.
Before, this functions didn't state the requirements clearly enough,
and I was not immediately able to find them like for other functions.
This doesn't change the content of the docs, but simply rewords them for
clarity.
use strict provenance APIs
The stdlib was adjusted to avoid bare int2ptr casts, but recently some casts of that sort have sneaked back in. Let's fix that. :)
implement ptr.addr() via transmute
As per the discussion in https://github.com/rust-lang/unsafe-code-guidelines/issues/286, the semantics for ptr-to-int transmutes that we are going with for now is to make them strip provenance without exposing it. That's exactly what `ptr.addr()` does! So we can implement `ptr.addr()` via `transmute`. This also means that once https://github.com/rust-lang/rust/pull/97684 lands, Miri can distinguish `ptr.addr()` from `ptr.expose_addr()`, and the following code will correctly be called out as having UB (if permissive provenance mode is enabled, which will become the default once the [implementation is complete](https://github.com/rust-lang/miri/issues/2133)):
```rust
fn main() {
let x: i32 = 3;
let x_ptr = &x as *const i32;
let x_usize: usize = x_ptr.addr();
// Cast back an address that did *not* get exposed.
let ptr = std::ptr::from_exposed_addr::<i32>(x_usize);
assert_eq!(unsafe { *ptr }, 3); //~ ERROR Undefined Behavior: dereferencing pointer failed
}
```
This completes the Miri implementation of the new distinctions introduced by strict provenance. :)
Cc `@Gankra` -- for now I left in your `FIXME(strict_provenance_magic)` saying these should be intrinsics, but I do not necessarily agree that they should be. Or if we have an intrinsic, I think it should behave exactly like the `transmute` does, which makes one wonder why the intrinsic should be needed.
Stabilize `{slice,array}::from_ref`
This PR stabilizes the following APIs as `const` functions in Rust `1.63`:
```rust
// core::array
pub const fn from_ref<T>(s: &T) -> &[T; 1];
// core::slice
pub const fn from_ref<T>(s: &T) -> &[T];
```
Note that the `mut` versions are not stabilized as unique references (`&mut _`) are [unstable in const context].
FCP: https://github.com/rust-lang/rust/issues/90206#issuecomment-1134586665
r? rust-lang/libs-api `@rustbot` label +T-libs-api -T-libs
[unstable in const context]: https://github.com/rust-lang/rust/issues/57349
Additional `*mut [T]` methods
Split out from #94247
This adds the following methods to raw slices that already exist on regular slices
* `*mut [T]::is_empty`
* `*mut [T]::split_at_mut`
* `*mut [T]::split_at_mut_unchecked`
These methods reduce the amount of unsafe code needed to migrate `ChunksMut` and related iterators
to raw slices (#94247)
r? `@m-ou-se`
Corrected EBNF grammar for from_str
Hello! This is my first time contributing to an open-source project. I'm excited to have the chance to contribute to the rust community 🥳
I noticed an issue with the documentation for `from_str` in `f32` and `f64`. It states that "All strings that adhere to the following [EBNF](https://www.w3.org/TR/REC-xml/#sec-notation) grammar when lowercased will result in an `Ok` being returned. I believe this is incorrect for the string `"."`, which is valid for the given EBNF grammar, but does not result in an `Ok` being returned ([playground](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=09f891aa87963a56d3b0d715d8cbc2b4)). I have simplified the grammar in a way which fixes that, but is otherwise identical.
Previously, the `Number` part of the EBNF grammar had an option for `'.' Digit*`, which would include the string `"."`. This is not valid, and does not return an Ok as stated. The corrected version removes this, and still allows for the `'.' Digit+` case with the already existing `Digit* '.' Digit+` case.
Add unicode fast path to `is_printable`
Before, it would enter the full expensive check even for normal ascii characters. Now, it skips the check for the ascii characters in `32..127`. This range was checked manually from the current behavior.
I ran the `tracing` test suite in miri, and it was really slow. I looked at a profile, and miri spent most of the time in `core::char::methods::escape_debug_ext`, where half of that was dominated by `core::unicode::printable::is_printable`. So I optimized it here.
The tracing profile:
Before, it would enter the full expensive check even for normal ascii
characters. Now, it skips the check for the ascii characters in
`32..127`. This range was checked manually from the current behavior.
