add module-level documentation for vec's in-place iteration
As requested in the last libs team meeting and during previous reviews.
Feel free to point out any gaps you encounter, after all non-obvious things may with hindsight seem obvious to me.
r? `@yaahc`
CC `@steffahn`
Rollup of 5 pull requests
Successful merges:
- #94249 (Better errors when a Copy impl on a Struct is not self-consistent)
- #95069 (Fix auto traits in rustdoc)
- #95221 (interpret/memory: simplify check_and_deref_ptr)
- #95225 (remove `[async output]` from `impl Future` pretty-printing)
- #95238 (Stop emitting E0026 for struct enums with underscores)
Failed merges:
r? `@ghost`
`@rustbot` modify labels: rollup
interpret/memory: simplify check_and_deref_ptr
*Finally* I saw a way to make this code simpler. The odd preprocessing in `let ptr_or_addr =` has bothered me since forever, but it actually became unnecessary in the last provenance refactoring. :)
This also leads to slightly more explicit error messages as a nice side-effect. 🎉
r? `@oli-obk`
Better errors when a Copy impl on a Struct is not self-consistent
As discovered in a Zulip thread with `@nnethercote` and `@Mark-Simulacrum,` it's not immediately obvious why a field on an ADT doesn't implement `Copy`. This PR attempts to give slightly more detailed information by spinning up a fulfillment context to try to dig down and discover transitive fulfillment errors that cause `is_copy_modulo_regions` to fail on a ADT field.
The error message still kinda sucks, but should only show up in the case that an existing error message was totally missing... so I think it's a good compromise for now?
diagnostics: do not suggest `fn foo({ <body> }`
Instead of suggesting that the body always replace the last character on the line, presuming it must be a semicolon, the parser should instead check what the last character is, and append the body if it is anything else.
Fixes#83104
Rename `~const Drop` to `~const Destruct`
r? `@oli-obk`
Completely switching to `~const Destructible` would be rather complicated, so it seems best to add it for now and wait for it to be backported to beta in the next release.
The rationale is to prevent complications such as #92149 and #94803 by introducing an entirely new trait. And `~const Destructible` reads a bit better than `~const Drop`. Name Bikesheddable.
Move std::sys::{mutex, condvar, rwlock} to std::sys::locks.
This cleans up the the std::sys modules a bit by putting the locks in a single module called `locks` rather than spread over the three modules `mutex`, `condvar`, and `rwlock`. This makes it easier to organise lock implementations, which helps with https://github.com/rust-lang/rust/issues/93740.
interpret/validity: improve clarity
I was confused by my own (ancient) comment in `validity.rs` so I figured I'd clarify. (And I don't think ZST-ness is relevant at all inside that branch, no idea where that comment comes from.)
Also `extend` seems more clear than `clone_from`.
Modernize `alloc-no-oom-handling` test
- The edition should be 2021 to avoid warnings.
- The `external_crate` feature was removed in commit 45bf1ed1a1 ("rustc: Allow changing the default allocator").
Note that commit d620ae1070 ("Auto merge of #84266") removed the old test, but the new one introduced passed the `--cfg` like in the old one.
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>
---
This is intended to align this test to the new `no_rc` and `no_sync` ones being added in https://github.com/rust-lang/rust/pull/89891, but it makes sense on its own too.
Add u16::is_utf16_surrogate
Right now, there are methods in the standard library for encoding and decoding UTF-16, but at least for the moment, there aren't any methods specifically for `u16` to help work with UTF-16 data. Since the full logic already exists, this wouldn't really add any code, just expose what's already there.
This method in particular is useful for working with the data returned by Windows `OsStrExt::encode_wide`. Initially, I was planning to also offer a `TryFrom<u16> for char`, but decided against it for now. There is plenty of code in rustc that could be rewritten to use this method, but I only checked within the standard library to replace them.
I think that offering more UTF-16-related methods to u16 would be useful, but I think this one is a good start. For example, one useful method might be `u16::is_pattern_whitespace`, which would check if something is the Unicode `Pattern_Whitespace` category. We can get away with this because all of the `Pattern_Whitespace` characters are in the basic multilingual plane, and hence we don't need to check for surrogates.
add perf side effect docs to `Iterator::cloned()`
Now that #90209 has been closed, as the current state of affairs is neither here nor there, this at least adds a paragraph + example on what to expect performance-wise and how to deal with it to the .cloned() docs.
cc `@the8472`
Fold aarch64 feature +fp into +neon
Arm's FEAT_FP and Feat_AdvSIMD describe the same thing on AArch64:
The Neon unit, which handles both floating point and SIMD instructions.
Moreover, a configuration for AArch64 must include both or neither.
Arm says "entirely proprietary" toolchains may omit floating point:
https://developer.arm.com/documentation/102374/0101/Data-processing---floating-point
In the Programmer's Guide for Armv8-A, Arm says AArch64 can have
both FP and Neon or neither in custom implementations:
https://developer.arm.com/documentation/den0024/a/AArch64-Floating-point-and-NEON
In "Bare metal boot code for Armv8-A", enabling Neon and FP
is just disabling the same trap flag:
https://developer.arm.com/documentation/dai0527/a
In an unlikely future where "Neon and FP" become unrelated,
we can add "[+-]fp" as its own feature flag.
Until then, we can simplify programming with Rust on AArch64 by
folding both into "[+-]neon", which is valid as it supersets both.
"[+-]neon" is retained for niche uses such as firmware, kernels,
"I just hate floats", and so on.
I am... pretty sure no one is relying on this.
An argument could be made that, as we are not an "entirely proprietary" toolchain, we should not support AArch64 without floats at all. I think that's a bit excessive. However, I want to recognize the intent: programming for AArch64 should be simplified where possible. For x86-64, programmers regularly set up illegal feature configurations because it's hard to understand them, see https://github.com/rust-lang/rust/issues/89586. And per the above notes, plus the discussion in https://github.com/rust-lang/rust/issues/86941, there should be no real use cases for leaving these features split: the two should in fact always go together.
- Fixesrust-lang/rust#95002.
- Fixesrust-lang/rust#95064.
- Fixesrust-lang/rust#95122.
Instead of suggesting that the body always replace the last character on the
line, presuming it must be a semicolon, the parser should instead check what
the last character is, and append the body if it is anything else.
Fixes#83104
