Clarify `async` block behaviour
Adds some documentation for control flow behaviour pertaining to `return` and `?` within `async` blocks. Fixes (or at least improves) #101444.
r? rust-lang/docs
Document that "extern blocks must be unsafe" in Rust 2024
The [documentation on `extern`](https://doc.rust-lang.org/std/keyword.extern.html) contains the following code sample:
```rust
#[link(name = "my_c_library")]
extern "C" {
fn my_c_function(x: i32) -> bool;
}
```
Due to #123743, attempting to compile such code with the 2024 edition of Rust fails:
```
error: extern blocks must be unsafe
```
This PR extends the `extern` documentation with a brief explanation of the new requirement. It also adds the missing `unsafe` keyword to the code sample, which should be compatible with rustc since v1.82.
**Related docs:**
- https://doc.rust-lang.org/reference/items/external-blocks.html
- https://doc.rust-lang.org/edition-guide/rust-2024/unsafe-extern.html
`CheckAttrVisitor::check_doc_keyword` checks `#[doc(keyword = "..")]`
attributes to ensure they are on an empty module, and that the value is
a non-empty identifier.
The `rustc::existing_doc_keyword` lint checks these attributes to ensure
that the value is the name of a keyword.
It's silly to have two different checking mechanisms for these
attributes. This commit does the following.
- Changes `check_doc_keyword` to check that the value is the name of a
keyword (avoiding the need for the identifier check, which removes a
dependency on `rustc_lexer`).
- Removes the lint.
- Updates tests accordingly.
There is one hack: the `SelfTy` FIXME case used to used to be handled by
disabling the lint, but now is handled with a special case in
`is_doc_keyword`. That hack will go away if/when the FIXME is fixed.
Co-Authored-By: Guillaume Gomez <guillaume1.gomez@gmail.com>
> `const` items looks remarkably similar to `static` items, [...]
Either this should be written as
> A `const` items looks remarkably similar to a `static` item,
or "looks" should be changed to "look".
I have selected the smaller diff.
`break` doesn't require a loop, so note this in the docs.
This is covered in the linked sections of the rust reference,
but this page implied that `break` is only for loops.
This PR will fix some typos detected by [typos].
I only picked the ones I was sure were spelling errors to fix, mostly in
the comments.
[typos]: https://github.com/crate-ci/typos
This updates the standard library's documentation to use the new syntax. The
documentation is worthwhile to update as it should be more idiomatic
(particularly for features like this, which are nice for users to get acquainted
with). The general codebase is likely more hassle than benefit to update: it'll
hurt git blame, and generally updates can be done by folks updating the code if
(and when) that makes things more readable with the new format.
A few places in the compiler and library code are updated (mostly just due to
already having been done when this commit was first authored).
Some improvements to the async docs
The goal here is to make the docs overall a little bit more comprehensive and add more links between the things.
One thing that's not working yet is the links to the keywords. Somehow I couldn't get them to work.
r? ````@GuillaumeGomez```` do you know how I could get the keyword links to work?
