Introduce RefCell::try_borrow_unguarded
*Come sit next to the fireplace with me, this is going to be a long story.*
So, you may already be aware that Servo has weird design constraints that forces us developers working on it to do weird things. The thing that interests us today is that we do layout on a separate thread with its own thread pool to do some things in parallel, whereas the data it uses comes from the script thread, which implements the entire DOM and related pieces, with `!Sync` data types such as `RefCell<T>`.
The invariant we maintain is that script does not do anything ever with the DOM data as long as layout is doing its job. That's all nice and all, but one thing we don't ensure is that we don't actually know if script was currently mutably borrowing some `RefCell<T>` prior to starting layout, which may lead to aliasing mutable memory and obviously undefined behaviour.
This PR reinstates `RefCell::borrow_state` so that [this method](https://github.com/servo/servo/blob/master/components/script/dom/bindings/cell.rs#L23-L30) can make use of it and return `None` if the cell was mutably borrowed.
Cc @SimonSapin
rustdoc: don't process `Crate::external_traits` when collecting intra-doc links
Part of https://github.com/rust-lang/rust/issues/58745, closes https://github.com/rust-lang/rust/pull/58917
The `collect-intra-doc-links` pass keeps track of the modules it recurses through as it processes items. This is used to know what module to give the resolver when looking up links. When looking through the regular items of the crate, this works fine, but the `DocFolder` trait as written doesn't just process the main crate hierarchy - it also processes the trait items in the `external_traits` map. This is useful for other passes (so they can strip out `#[doc(hidden)]` items, for example), but here it creates a situation where we're processing items "outside" the regular module hierarchy. Since everything in `external_traits` is defined outside the current crate, we can't fall back to finding its module scope like we do with local items.
Skipping this collection saves us from emitting some spurious warnings. We don't even lose anything by skipping it, either - the docs loaded from here are only ever rendered through `html::render::document_short` which strips any links out, so the fact that the links haven't been loaded doesn't matter. Hopefully this removes most of the remaining spurious resolution warnings from intra-doc links.
r? @GuillaumeGomez
When encountering one of a few keywords when a semicolon was
expected, suggest the semicolon and recover:
```
error: expected one of `.`, `;`, `?`, or an operator, found `let`
--> $DIR/recover-missing-semi.rs:4:5
|
LL | let _: usize = ()
| - help: missing semicolon here
LL |
LL | let _ = 3;
| ^^^
error[E0308]: mismatched types
--> $DIR/recover-missing-semi.rs:2:20
|
LL | let _: usize = ()
| ^^ expected usize, found ()
|
= note: expected type `usize`
found type `()`
```
This commit implements the `{read,write}_vectored` methods on more types
in the standard library, namely:
* `std::fs::File`
* `std::process::ChildStd{in,out,err}`
* `std::io::Std{in,out,err}`
* `std::io::Std{in,out,err}Lock`
* `std::io::Std{in,out,err}Raw`
Where supported the OS implementations hook up to native support,
otherwise it falls back to the already-defaulted implementation.
