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
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.
Allow #[repr(align(x))] on enums (#57996)
Tracking issue: #57996
Implements an extension of [RFC 1358](https://github.com/rust-lang/rfcs/blob/master/text/1358-repr-align.md) behind a feature flag (`repr_align_enum`). Originally introduced here for structs: #39999.
It seems like only HIR-level changes are required, since enums are already aware of their alignment (due to alignment of their limbs).
cc @bitshifter
Document that `-C opt-level=0` implies `-C debug-assertions`.
I couldn't find it stated anywhere else (https://doc.rust-lang.org/nightly/rustc/codegen-options/index.html#opt-level).
It was a problem before here: https://github.com/rust-lang/rust/issues/39449, it got lost in the migration to the new documentation I assume.
On a sidenote: I think that `-C opt-level=0` having a sideeffect on another flag should be changed. Having compiler flags affecting others doesn't make much sense to me, they are used to fine tune anyway.
In any case, this plays no role in this PR.
