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
doc: use correct body font URLs
The CSS for the docs homepage (docs.rust-lang.org) was using the wrong
URL for the body font, resulting in the fallback serif font being used,
instead of the desired Source Serif Pro fonts.
(It's worth noting that the CSS for rustdoc's API generation got these URLs right.)
Exclude old book redirect stubs from search engines
Adds `<meta name="robots" content="noindex,follow">` to the `<head>` of old stub pages pointing to the second edition of the book.
This is continuation of https://github.com/rust-lang/book/pull/1788
The CSS for the docs homepage (docs.rust-lang.org) was using the wrong
URL for the body font, resulting in the fallback serif font being used,
instead of the desired Source Serif Pro fonts.
rustdoc: add option to calculate "documentation coverage"
This PR adds a new flag to rustdoc, `--show-coverage`. When passed, this flag will make rustdoc count the number of items in a crate with documentation instead of generating docs. This count will be output as a table of each file in the crate, like this (when run on my crate `egg-mode`):
```
+-------------------------------------+------------+------------+------------+
| File | Documented | Total | Percentage |
+-------------------------------------+------------+------------+------------+
| src/auth.rs | 16 | 16 | 100.0% |
| src/common/mod.rs | 1 | 1 | 100.0% |
| src/common/response.rs | 9 | 9 | 100.0% |
| src/cursor.rs | 24 | 24 | 100.0% |
| src/direct/fun.rs | 6 | 6 | 100.0% |
| src/direct/mod.rs | 41 | 41 | 100.0% |
| src/entities.rs | 50 | 50 | 100.0% |
| src/error.rs | 27 | 27 | 100.0% |
| src/lib.rs | 1 | 1 | 100.0% |
| src/list/fun.rs | 19 | 19 | 100.0% |
| src/list/mod.rs | 22 | 22 | 100.0% |
| src/media/mod.rs | 27 | 27 | 100.0% |
| src/place/fun.rs | 8 | 8 | 100.0% |
| src/place/mod.rs | 35 | 35 | 100.0% |
| src/search.rs | 26 | 26 | 100.0% |
| src/service.rs | 74 | 74 | 100.0% |
| src/stream/mod.rs | 49 | 49 | 100.0% |
| src/tweet/fun.rs | 15 | 15 | 100.0% |
| src/tweet/mod.rs | 73 | 73 | 100.0% |
| src/user/fun.rs | 24 | 24 | 100.0% |
| src/user/mod.rs | 87 | 87 | 100.0% |
+-------------------------------------+------------+------------+------------+
| Total | 634 | 634 | 100.0% |
+-------------------------------------+------------+------------+------------+
```
Trait implementations are not counted because by default they "inherit" the docs from the trait, even though an impl can override those docs. Similarly, inherent impl blocks are not counted at all, because for the majority of cases such docs are not useful. (The usual pattern for inherent impl blocks is to throw all the methods on a type into a single impl block. Any docs you would put on that block would be better served on the type itself.)
In addition, `--show-coverage` can be combined with `--document-private-items` to get the coverage counts for everything in the crate, not just public items.
The coverage calculation is implemented as a late pass and two new sets of passes which strip out most of the work that rustdoc otherwise does when generating docs. The is because after the new pass is executed, rustdoc immediately closes instead of going on to generate documentation.
Many examples of coverage calculations have been included as `rustdoc-ui` tests.
r? @rust-lang/rustdoc
Deny the `overflowing_literals` lint for all editions
The `overflowing_literals` was made deny by default for the 2018 edition by #54507, however I'm not aware of any reason it can't be made deny by default for the 2015 edition as well.
Fix doc for rustc "-g" flag
The rustc `-g` CLI flag was miss documented to be a synonym of `-C debug-level=2` and not `-C debuglevel=2`. Also add links to the codegen docs for each synonym.
I am unsure of this will conflict with work on #52938
Modify doctest's auto-`fn main()` to allow `Result`s
This lets the default `fn main()` ~~return `impl Termination`~~ unwrap Results, which allows the use of `?` in most tests without adding it manually. This fixes#56260
~~Blocked on `std::process::Termination` stabilization.~~
Using `Termination` would have been cleaner, but this should work OK.
