libcore/net: `IpAddr::as_octets()`
[ACP](https://github.com/rust-lang/libs-team/issues/535)
[Tracking issue](https://github.com/rust-lang/rust/issues/137259)
Adds `const` `core::net::IpAddr{,v4,v6}::as_octets()` methods to provide reference access to IP address contents.
The concrete usecase for me is allowing the `IpAddr` to provide an extended lifetime in contexts that want a `&[u8]`:
```rust
trait AddrSlice {
fn addr_slice(&self) -> &[u8];
}
impl AddrSlice for IpAddrV4 {
fn addr_slice(&self) -> &[u8] {
// self.octets() doesn't help us here, because we can't return a reference to the owned array.
// Instead we want the IpAddrV4 to continue owning the memory:
self.as_octets()
}
}
```
(Notably, in this case we can't parameterize `AddrSlice` by a `const N: usize` (such that `fn addr_slice(&self) -> [u8; N]`) and maintain object-safety.)
Optionally add type names to `TypeId`s.
This feature is intended to provide expensive but thorough help for developers who have an unexpected `TypeId` value and need to determine what type it actually is. It causes `impl Debug for TypeId` to print the type name in addition to the opaque ID hash, and in order to do so, adds a name field to `TypeId`. The cost of this is the increased size of `TypeId` and the need to store type names in the binary; therefore, it is an optional feature. It does not expose any new public API, only change the `Debug` implementation.
It may be enabled via `cargo -Zbuild-std -Zbuild-std-features=debug_typeid`. (Note that `-Zbuild-std-features` disables default features which you may wish to reenable in addition; see
<https://doc.rust-lang.org/cargo/reference/unstable.html#build-std-features>.)
Example usage and output:
```
fn main() {
use std::any::{Any, TypeId};
dbg!(TypeId::of::<usize>(), drop::<usize>.type_id());
}
```
```
TypeId::of::<usize>() = TypeId(0x763d199bccd319899208909ed1a860c6 = usize)
drop::<usize>.type_id() = TypeId(0xe6a34bd13f8c92dd47806da07b8cca9a = core::mem::drop<usize>)
```
Also added feature declarations for the existing `debug_refcell` feature so it is usable from the `rust.std-features` option of `config.toml`.
Related issues:
* #68379
* #61533
Stabilize `num_midpoint_signed` feature
This PR proposes that we stabilize the signed variants of [`iN::midpoint`](https://github.com/rust-lang/rust/issues/110840#issue-1684506201), the operation is equivalent to doing `(a + b) / 2` in a sufficiently large number.
The stabilized API surface would be:
```rust
/// Calculates the middle point of `self` and `rhs`.
///
/// `midpoint(a, b)` is `(a + b) / 2` as if it were performed in a
/// sufficiently-large signed integer type. This implies that the result is
/// always rounded towards zero and that no overflow will ever occur.
impl i{8,16,32,64,128,size} {
pub const fn midpoint(self, rhs: Self) -> Self;
}
```
T-libs-api previously stabilized the unsigned (and float) variants in #131784, the signed variants were left out because of the rounding that should be used in case of negative midpoint.
This stabilization proposal proposes that we round towards zero because:
- it makes the obvious `(a + b) / 2` in a sufficiently-large number always true
- using another rounding for the positive result would be inconsistent with the unsigned variants
- it makes `midpoint(-a, -b)` == `-midpoint(a, b)` always true
- it is consistent with `midpoint(a as f64, b as f64) as i64`
- it makes it possible to always suggest `midpoint` as a replacement for `(a + b) / 2` expressions *(which we may want to do as a future work given the 21.2k hits on [GitHub Search](https://github.com/search?q=lang%3Arust+%2F%5C%28%5Ba-zA-Z_%5D*+%5C%2B+%5Ba-zA-Z_%5D*%5C%29+%5C%2F+2%2F&type=code&p=1))*
`@scottmcm` mentioned a drawback in https://github.com/rust-lang/rust/pull/132191#issuecomment-2439891200:
> I'm torn, because rounding towards zero makes it "wider" than other values, which `>> 1` avoids -- `(a + b) >> 1` has the nice behaviour that `midpoint(a, b) + 2 == midpoint(a + 2, b + 2)`.
>
> But I guess overall sticking with `(a + b) / 2` makes sense as well, and I do like the negation property 🤷
Which I think is outweigh by the advantages cited above.
Closes#110840
cc `@rust-lang/libs-api`
cc `@scottmcm`
r? `@dtolnay`
Organize `OsString`/`OsStr` shims
Synchronize the `bytes.rs` and `wtf8.rs` shims for `OsString`/`OsStr` so they're easier to diff between each other. This is mostly ordering items the same between the two. I tried to minimize moves and went for the average locations between the files.
With them in the same order, it is clear that `FromInner<_>` is not implemented for `bytes::Buf` and `Clone::clone_from` is not implemented for `wtf8::Buf`, but they are for the other. Fix that.
I added #[inline] to all inherent methods of the `OsString`/`OsStr` shims, because it seemed that was already the rough pattern. `bytes.rs` has more inlining than `wtf8.rs`, so I added the corresponding ones to `wtf8.rs`. Then, the common missing ones have no discernible pattern to me. They're not divided by non-allocating/allocating. Perhaps the pattern is that UTF-8 validation isn't inlined? Since these types are merely the inner values in `OsStr`/`OsString`, I put inline on all methods and let those public types dictate inlining. I have not inspected codegen or run benchmarks.
Also, touch up some (private) documentation comments.
r? ``````@ChrisDenton``````
Lint `#[must_use]` attributes applied to methods in trait impls
The `#[must_use]` attribute has no effect when applied to methods in trait implementations. This PR adds it to the unused `#[must_use]` lint, and cleans the extra attributes in portable-simd and Clippy.
Use more explicit and reliable ptr select in sort impls
Using `if ...` with the intent to avoid branches can be surprising to readers and carries the risk of turning into jumps/branches generated by some future compiler version, breaking crucial optimizations.
This commit replaces their usage with the explicit and IR annotated `bool::select_unpredictable`.
Impl TryFrom<Vec<u8>> for String
I think this is useful enough to have :)
As a general question, is there any policy around adding "missing" trait implementations? (like adding `AsRef<T> for T` for std types), I mostly stumble upon them when using a lot of "impl Trait in argument position" like (`foo: impl Into<String>`)
Add `MAX_LEN_UTF8` and `MAX_LEN_UTF16` Constants
This pull request adds the `MAX_LEN_UTF8` and `MAX_LEN_UTF16` constants as per #45795, gated behind the `char_max_len` feature.
The constants are currently applied in the `alloc`, `core` and `std` libraries.
Add a bullet point to `std::fs::copy`
I needed to copy a file but I got the following error:
```
Os { code: 2, kind: NotFound, message: "No such file or directory" }
```
After read the documentation, I though the error was generated by the `from` parameter, forgetting the `to` part. Anyway, I got the error because the parent folder of `to` didn't exist.
Even if the documentation explicitly saying `but is not limited to just these cases`, I would like to add this case because I spent 3 hours around it.
This PR just wants to put a mention about it.
Adds `const` `Ip*Addr::as_octets` methods providing reference access to
`Ip*Addr` octets contents.
See https://github.com/rust-lang/libs-team/issues/535 for accepted ACP
with a more detailed justification.
fix docs for inherent str constructors
related to #131114
when implementing inherent str constructors in #136517, i forgot to change the docs, so the code examples still imported the `std::str` module and used the constructor from there, instead of using "itself" (the inherent constructor).
Locking documentation updates
- Reword file lock documentation to clarify advisory vs mandatory. Remove the
word "advisory", and make it more explicit that the lock may be advisory or
mandatory depending on platform.
- Document that locking a file fails on Windows if the file is opened only for append
Remove `std::os::wasi::fs::FileExt::tell`
Following #137165 (Use `tell` for `<File as Seek>::stream_position`), `tell` is now directly exposed via `stream_position`, making `<File as FileExt>::tell` redundant. Remove it.
`std::os::wasi::fs::FileExt::tell` is currently unstable and tracked in https://github.com/rust-lang/rust/issues/71213.
``@rustbot`` ping wasi
tests: Also gate `f16::erfc()` doctest with `reliable_f16_math` cfg
In #136324 the doctest for `f16::erf()` was gated with `reliable_f16_math`. Add the same gate on `f16::erfc()` to avoid:
rust_out.71e2e529d20ea47d-cgu.0:\
(.text._ZN8rust_out4main43_doctest_main_library_std_src_f16_rs_1321_017h485f3ffe6bf2a981E+0x38): \
undefined reference to `__gnu_h2f_ieee'
on MIPS (and maybe other architectures).
r? tgross35
Make ub_check message clear that it's not an assert
I've seen a user assume that their unsound code was *safe*, because ub_check prevented the program from performing the unsafe operation.
This PR makes the panic message clearer that ub_check is a bug detector, not run-time safety protection.
Following #137165 (Use `tell` for `<File as Seek>::stream_position`),
`tell` is now directly exposed via `stream_position`, making
`<File as FileExt>::tell` redundant. Remove it.
Use `tell` for `<File as Seek>::stream_position`
Some platforms have a more efficient way to get the current offset of the file than by seeking. For example, Wasi has `fd_tell` and SOLID has `SOLID_FS_Ftell`. Implement `<File as Seek>::stream_position()` in terms of those.
I do not use any APIs that were not already used in `std`. Although, the `libc` crate has [`ftell`](https://docs.rs/libc/latest/libc/fn.ftell.html), [`ftello`](https://docs.rs/libc/latest/libc/fn.ftello.html), and [`ftello64`](https://docs.rs/libc/latest/libc/fn.ftello64.html), I do not know platform coverage. It appears that Windows has no `tell`-like API.
I have checked that it builds on each relevant platform.
Rollup of 7 pull requests
Successful merges:
- #137095 (Replace some u64 hashes with Hash64)
- #137100 (HIR analysis: Remove unnecessary abstraction over list of clauses)
- #137105 (Restrict DerefPure for Cow<T> impl to T = impl Clone, [impl Clone], str.)
- #137120 (Enable `relative-path-include-bytes-132203` rustdoc-ui test on Windows)
- #137125 (Re-add missing empty lines in the releases notes)
- #137145 (use add-core-stubs / minicore for a few more tests)
- #137149 (Remove SSE ABI from i586-pc-windows-msvc)
r? `@ghost`
`@rustbot` modify labels: rollup
In 136324 the doctest for `f16::erf()` was gated with
`reliable_f16_math`. Add the same gate on `f16::erfc()` to
avoid:
rust_out.71e2e529d20ea47d-cgu.0:\
(.text._ZN8rust_out4main43_doctest_main_library_std_src_f16_rs_1321_017h485f3ffe6bf2a981E+0x38): \
undefined reference to `__gnu_h2f_ieee'
on MIPS (and maybe other architectures).
Restrict DerefPure for Cow<T> impl to T = impl Clone, [impl Clone], str.
Fixes#136046
`feature(deref_patterns)` tracking issue: https://github.com/rust-lang/rust/issues/87121
`Cow<'_, T>` should only implement `DerefPure` if its `Deref` impl is pure, which requires `<T::Owned as Borrow<T>>::borrow` to be pure. This PR restricts `impl DerefPure for Cow<'_, T>` to `T: Sized + Clone`, `T = [U: Clone]`, and `T = str` (for all of whom `<T::Owned as Borrow<T>>::borrow` is implemented in the stdlib and is pure).
cc ``@Nadrieril``
------
An alternate approach would be to introduce a new `unsafe trait BorrowPure<T>` analogous to `DerefPure` that could be implemented for `T: Sized`, `&T`, `&mut T`, `String`, `Vec`, `Box`, `PathBuf`, `OsString`, etc. https://github.com/rust-lang/rust/compare/master...zachs18:borrow-pure-trait
Use `const_error!` when possible
Replace usages of `io::Error::new(io::ErrorKind::Variant, "constant string")` with `io::const_error!(io::ErrorKind::Variant, "constant string")` to avoid allocations when possible. Additionally, fix `&&str` error messages in SGX and missing/misplaced trailing commas in `const_error!`.
* Order items as the average of the two adaptors. Enables easier diffs.
* Consistently apply #[inline].
* Implement FromInner<Vec<u8>> for bytes::Buf.
* Implement Clone::clone_from for wtf8::Buf.
