Clarify error returns from Mutex::try_lock, RwLock::try_read,
RwLock::try_write to make it more obvious that both poisoning
and the lock being already locked are possible errors.

…thin

Use "the `WouldBlock` error" instead of "the error `WouldBlock`", etc.

…module to the methods themselves

Avoid CJK legacy fonts in Windows

As metioned in rust-lang#84035, the default serif CJK font in Windows is meh-looking.
To avoid this, we should use sans-serif font or provide CJK glyph supported font in `rustdoc.css`.

doc: clarify Mutex::try_lock, etc. errors

Clarify error returns from Mutex::try_lock, RwLock::try_read,
RwLock::try_write to make it more obvious that both poisoning
and the lock being already locked are possible errors.

…=Mark-Simulacrum

Fix bootstrap using host exe suffix for cargo

When attempting to cross compile rustc (for example, from Linux to Windows) and tell it to build cargo/tools, the following error occurs:

```
thread 'main' panicked at 'src.symlink_metadata() failed with No such file or directory (os error 2)', src/bootstrap/lib.rs:1196:24
```

Relevant part of stack trace:
<details>

```
   2: bootstrap::Build::copy
             at ./src/bootstrap/lib.rs:1196:24
   3: <bootstrap::tool::ToolBuild as bootstrap::builder::Step>::run
             at ./src/bootstrap/tool.rs:220:13
```
</details>

If I add `-vvv` (which seemed to be the recommended course for debugging a similar issue according to [zulip logs](https://zulip-archive.rust-lang.org/182449tcompilerhelp/19655failedtobootstrap.html)), it shows:

```
Copy ".../rust/build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-pc-windows-gnu/release/cargo" to ".../rust/build/x86_64-unknown-linux-gnu/stage2-tools-bin/cargo"
```
and when taking a look at the contents of `build/x86_64-unknown-linux-gnu/stage2-tools/x86_64-pc-windows-gnu/release` it contains `cargo.exe`, but no `cargo`.

I tried to study the surrounding code to make sure this was the intended behavior and while I can't be 100% certain, it does seem that using the exe suffix for the `compiler.host` target instead of the `target` target won't have the desired behavior when cross-compiling to/from Windows.

…e, r=oli-obk

Fix pointer provenance in <[T]>::copy_within

Previously the `self.as_mut_ptr()` invalidated the pointer created by the first `self.as_ptr()`. This also triggered miri when run with `-Zmiri-track-raw-pointers`

…k-Simulacrum

Remove stray .stderr files

The revisions for the test were [changed in rust-lang#85555](https://github.com/rust-lang/rust/pull/85555/files#diff-f353939cf3762b63a04bae4d9c1c919039b64351bc4d8722ad894509f6015b0f) but the files weren't deleted.

Demote `ControlFlow::{from|into}_try` to `pub(crate)`

They have mediocre names and non-obvious semantics, so personally I don't think they're worth trying to stabilize, and thus might as well just be internal (they're used for convenience in iterator adapters), not something shown in the rustdocs.

I don't think anyone actually wanted to use them outside `core` -- they just got made public-but-unstable along with the whole type in rust-lang#76204 that promoted `LoopState` from an internal type to the exposed `ControlFlow` type.

cc rust-lang#75744, the tracking issue they mention.
cc rust-lang#85608, the PR where I'm proposing stabilizing the type.

…nd, r=jyn514

Revert "Move llvm submodule updates to rustbuild"

Reverts rust-lang#81601

This updates LLVM a bit too eagerly -- and particularly on Windows, this can be slow. See discussion on [Zulip].

[Zulip]: https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/x.2Epy.20always.20updates.20LLVM.20submodule

… r=dtolnay

Document shared_from_cow functions

…Simulacrum

Fix tasklist example in rustdoc book.

There were a few issues with the tasklist example in the rustdoc book:

* Misspelled "incomplete"
* Checkmarks were backwards
* Didn't show the text for each item
* Used HTML which renders differently from how markdown renders it (which uses "disabled" marks)
* Didn't use blockquotes to offset the example like the other extensions do
* Missing a colon

Before:
<img width="160" alt="image" src="https://user-images.githubusercontent.com/43198/119503519-e7787880-bd1f-11eb-9f13-1c67754ce001.png">

After:
<img width="220" alt="image" src="https://user-images.githubusercontent.com/43198/119503449-d6c80280-bd1f-11eb-9ab5-fe4a6df82124.png">

Move stability attribute for items under the `ip` feature

The `#[unstable]` attribute for items under the `ip` feature is currently located on the `std::net::ip` module itself. This is unusual, and less readable. This has sidetracked discussion about these items numerous times (rust-lang#60145 (comment), rust-lang#76098 (comment), rust-lang#76098 (comment), rust-lang#75019 (comment), rust-lang#75019 (comment)) and lead to incorrect assumptions about which items are actually stable (rust-lang#60145 (comment), rust-lang#76098 (comment)).

This PR moves the attribute from the module to the items themselves.

Update books

## reference

4 commits in 5aa457bf1b54bd2cd5d4cf49797f29299bdf89a7..9c68af3ce6ccca2395e1868addef26a0542e9ddd
2021-05-05 08:39:22 -0700 to 2021-05-24 09:53:32 -0700
- missing parameter name in Trait Implementations (rust-lang/reference#1030)
- Add more content to impl-trait.md (rust-lang/reference#1017)
- Document extended key-value attributes (rust-lang/reference#1029)
- Document raw pointer <-> usize casts. (rust-lang/reference#970)

## rust-by-example

1 commits in 5f8c6da200ada77760a2fe1096938ef58151c9a6..805e016c5792ad2adabb66e348233067d5ea9f10
2021-04-29 08:08:01 -0300 to 2021-05-20 17:08:34 -0300
- Update structs.md (rust-lang/rust-by-example#1440)

## rustc-dev-guide

4 commits in 1e6c7fbda4c45e85adf63ff3f82fa9c870b1447f..50de7f0682adc5d95ce858fe6318d19b4b951553
2021-05-10 13:38:24 +0900 to 2021-05-20 15:02:20 +0200
- update rustfmt references to reflect change from submod to subtree (rust-lang/rustc-dev-guide#1129)
- Remove `--stage 1` argument from `doc` invocations (rust-lang/rustc-dev-guide#1125)
- Update coverage docs (rust-lang/rustc-dev-guide#1122)
- Document -Zunpretty=thir-tree (rust-lang/rustc-dev-guide#1128)

## edition-guide

1 commits in 1da3c411f17adb1ba5de1683bb6acee83362b54a..302a115e8f71876dfc884aebb0ca5ccb02b8a962
2021-02-16 16:46:40 -0800 to 2021-05-21 10:46:11 -0400
- Minimize the edition guide (rust-lang/edition-guide#232)

## embedded-book

1 commits in 569c3391f5c0cc43433bc77831d17f8ff4d76602..7349d173fa28a0bb834cf0264a05286620ef0923
2021-04-07 08:32:11 +0000 to 2021-05-25 13:59:05 +0000
- Remove $ from cargo-binutils  (rust-embedded/book#292)

Update cargo

7 commits in 070e459c2d8b79c5b2ac5218064e7603329c92ae..e931e4796b61de593aa1097649445e535c9c7ee0
2021-05-11 18:12:23 +0000 to 2021-05-24 16:17:27 +0000
- Add `cargo:rustc-link-arg-bin` flag. (rust-lang/cargo#9486)
- Add a cargo-doc.browser config option (rust-lang/cargo#9473)
- Fix bug when with resolver = "1" non-virtual package was allowing unknown features (rust-lang/cargo#9437)
- Add GitHub link to contributor guide. (rust-lang/cargo#9493)
- Add temporary fix for rustup on windows in CI. (rust-lang/cargo#9498)
- 3 typos and some capitalization (rust-lang/cargo#9495)
- fix 6 typos (rust-lang/cargo#9484)