atomics: allow atomic and non-atomic reads to race
We currently define our atomics in terms of C++ `atomic_ref`. That has the unfortunate side-effect of making it UB for an atomic and a non-atomic read to race (concretely, [this code](https://play.rust-lang.org/?version=stable&mode=debug&edition=2021&gist=d1a743774e60923db33def7fe314d754) has UB). There's really no good reason for this, all the academic models of the C++ memory model I am aware of allow this -- C++ just disallows this because of their insistence on an "object model" with typed memory, where `atomic_ref` temporarily creates an "atomic object" that may not be accesses via regular non-atomic operations.
So instead of tying our operations to `atomic_ref`, let us tie them directly to the underlying C++ memory model. I am not sure what is the best way to phrase this, so here's a first attempt.
We also carve out an exception from the "no mixed-size atomic accesses" rule to permit mixed-size atomic reads -- given that we permit mixed-size non-atomic reads, it seems odd that this would be disallowed for atomic reads. However, when an atomic write races with any other atomic operation, they must use the same size.
With this change, it is finally the case that every non-atomic access can be replaced by an atomic access without introducing UB.
Cc `@rust-lang/opsem` `@chorman0773` `@m-ou-se` `@WaffleLapkin` `@Amanieu`
Fixes https://github.com/rust-lang/unsafe-code-guidelines/issues/483
Rename a few tests to make tidy happier
A somewhat random smattering of tests that I have recently looked at, and thus had cause to research and write down the reason for their existence.
Revert space-saving operations
The "all of our artifacts" `mv` seems like it may save enough space to matter sometimes, since it can range up to a gigabyte of difference, if memory serves. For the rest, I think we're good.
try-job: dist-aarch64-apple
rustdoc: update `ProcMacro` docs section on helper attributes
I believe the mention of attribute macros in the section on proc macro helper attributes is erroneous. As far as I can tell, attribute macros cannot define helper attributes.
The following attribute macro is not valid (fails to build), no matter how I try to define (or skip defining) the helpers:
```rust
#[proc_macro_attribute(attributes(helper))]
pub fn attribute_helpers(_attr: TokenStream, item: TokenStream) -> TokenStream {
item
}
```
The [language reference](https://doc.rust-lang.org/reference/procedural-macros.html#attribute-macros) also doesn't seem to mention attribute macro helpers. The helpers subsection is inside the section on derive macros.
etc: Add sample rust-analyzer configs for eglot & helix
LSP configuration in editors like Emacs (eglot) and helix does not
use the same JSON format as vscode and vim do. It is not obvious
how to set up LSP for rustc in those editors and the dev guide currently
does not cover them. Adding sample configuration files for those editors
alongside the currently existing JSON one would be helpful.
I figured having those included in the repo like the JSON one might save
someone some time and frustration otherwise spent on trying to get the
more niche editors' LSP to work properly. I'll add a section in the dev
guide too.
This partially reverts commit fe7c97c2e7.
I kept a mv, not a cp, for the one that shuffles major artifacts around,
because the size of those artifacts are big enough to matter, sometimes.
I don't think the diagnostic info will be that heavy, by comparison.
I believe the mention of attribute macros in the section on proc macro helper attributes is erroneous. As far as I can tell, attribute macros cannot define helper attributes.
The following attribute macro is not valid (fails to build), no matter how I try to define (or skip defining) the helpers:
```rust
#[proc_macro_attribute(attributes(helper))]
pub fn attribute_helpers(_attr: TokenStream, item: TokenStream) -> TokenStream {
item
}
```
The [language reference](https://doc.rust-lang.org/reference/procedural-macros.html#attribute-macros) also doesn't seem to mention attribute macro helpers. The helpers subsection is inside the section on derive macros.
LSP configuration in editors like Emacs (eglot) and helix does not
use the same JSON format as vscode and vim do. It is not obvious
how to set up LSP for rustc in those editors and the dev guide currently
does not cover them. Adding sample configuration files for those editors
alongside the currently existing JSON one would be helpful.
rustdoc perf: clone `clean::Item` less
In https://github.com/rust-lang/rust/pull/130798, I caused a small perf regression for rustdoc (see https://github.com/rust-lang/rust/pull/130807#issuecomment-2373116917), so here is a small improvement to make up for it 😺.
This change is actually unrelated to the minor perf regression in `Item::stability` and instead fixes a more relevant perf problem that I found while investigating: For certain crates with many impls on type aliases, we unnecessarily cloned large `clean::Item`s multiple times -- now we just borrow them.
On implicit `Sized` bound on fn argument, point at type instead of pattern
Instead of
```
error[E0277]: the size for values of type `(dyn ThriftService<(), AssocType = _> + 'static)` cannot be known at compilation time
--> $DIR/issue-59324.rs:23:20
|
LL | fn with_factory<H>(factory: dyn ThriftService<()>) {}
| ^^^^^^^ doesn't have a size known at compile-time
```
output
```
error[E0277]: the size for values of type `(dyn ThriftService<(), AssocType = _> + 'static)` cannot be known at compilation time
--> $DIR/issue-59324.rs:23:29
|
LL | fn with_factory<H>(factory: dyn ThriftService<()>) {}
| ^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
```
[rustdoc] Remove unneeded jinja comments
This is a follow-up of https://github.com/rust-lang/rust/pull/130585.
Since we now check for the jinja comments we missed, we can now check for the jinja comments which are unneeded. It will make the parsing and therefore the compilation a tiny bit faster (well, if anyone sees a difference haha). The real goal is mostly to have easier to read template files. 😉
r? ``@notriddle``
Instead of
```
error[E0277]: the size for values of type `(dyn ThriftService<(), AssocType = _> + 'static)` cannot be known at compilation time
--> $DIR/issue-59324.rs:23:20
|
LL | fn with_factory<H>(factory: dyn ThriftService<()>) {}
| ^^^^^^^ doesn't have a size known at compile-time
```
output
```
error[E0277]: the size for values of type `(dyn ThriftService<(), AssocType = _> + 'static)` cannot be known at compilation time
--> $DIR/issue-59324.rs:23:29
|
LL | fn with_factory<H>(factory: dyn ThriftService<()>) {}
| ^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
```
Rollup of 11 pull requests
Successful merges:
- #130279 (Document subtleties of `ManuallyDrop`)
- #130517 (Add the library workspace to the suggested rust-analyzer config)
- #130820 (Fix diagnostics for coroutines with () as input.)
- #130833 (Fix the misleading diagnostic for `let_underscore_drop` on type without `Drop` implementation)
- #130845 (Utf8Chunks: add link to Utf8Chunk)
- #130850 (Pass Module Analysis Manager to Standard Instrumentations)
- #130861 (Use `mem::offset_of!` for `sockaddr_un.sun_path`)
- #130862 (rustdoc: do not animate :target when user prefers reduced motion)
- #130868 (Update FIXME comment in s390x_unknown_linux_*.rs)
- #130879 (Pass correct HirId to late_bound_vars in diagnostic code)
- #130880 (add missing FIXME(const-hack))
r? `@ghost`
`@rustbot` modify labels: rollup
rustdoc: do not animate :target when user prefers reduced motion
This accessibility improvement gates #129284 behind an inverted [prefers-reduced-motion](https://developer.mozilla.org/en-US/docs/Web/CSS/`@media/prefers-reduced-motion)` media query.
