In https://reviews.llvm.org/D102093 lots of things stopped taking the
DebugLogging boolean parameter. Mercifully we appear to always set
DebugPassManager to false, so I don't think we're losing anything by not
passing this parameter.

The makes the code for handling "auto-hide" settings more consistent.

…m/aarch64

…forms can specialize it

…nieu

Update list of allowed aarch64 features

I recently added these features to std_detect for aarch64 linux, pending [review](rust-lang/stdarch#1146).

I have commented any features not supported by LLVM 9, the current minimum version for Rust. Some (PAuth at least) were renamed between 9 & 12 and I've left them disabled. TME, however, is not in LLVM 9 but I've left it enabled.

See rust-lang/stdarch#993

Introduce `sys_common::rt::rtprintpanic!` to replace `sys_common::util` functionality

This PR introduces a new macro `rtprintpanic!`, similar to `sys_common::util::dumb_print` and uses that macro to replace all `sys_common::util` functionality.

impl FromStr for proc_macro::Literal

Note that unlike `impl FromStr for proc_macro::TokenStream`, this impl does not permit whitespace or comments. The input string must consist of nothing but your literal.

- `"1".parse::<Literal>()` ⟶ ok

- `"1.0".parse::<Literal>()` ⟶ ok

- `"'a'".parse::<Literal>()` ⟶ ok

- `"\"\n\"".parse::<Literal>()` ⟶ ok

- `"0 1".parse::<Literal>()` ⟶ LexError

- `" 0".parse::<Literal>()` ⟶ LexError

- `"0 ".parse::<Literal>()` ⟶ LexError

- `"/* comment */0".parse::<Literal>()` ⟶ LexError

- `"0/* comment */".parse::<Literal>()` ⟶ LexError

- `"0// comment".parse::<Literal>()` ⟶ LexError

---

## Use case

```rust
let hex_int: Literal = format!("0x{:x}", int).parse().unwrap();
```

The only way this is expressible in the current API is significantly worse.

```rust
let hex_int = match format!("0x{:x}", int)
    .parse::<TokenStream>()
    .unwrap()
    .into_iter()
    .next()
    .unwrap()
{
    TokenTree::Literal(literal) => literal,
    _ => unreachable!(),
};
```

Windows implementation of feature `path_try_exists`

Draft of a Windows implementation of `try_exists` (rust-lang#83186).

The first commit reorganizes the code so I would be interested to get some feedback on if this is a good idea or not. It moves the `Path::try_exists` function to `fs::exists`. leaving the former as a wrapper for the latter. This makes it easier to provide platform specific implementations and matches the `fs::metadata` function.

The other commit implements a Windows specific variant of `exists`. I'm still figuring out my approach so this is very much a first draft. Eventually this will need some more eyes from knowledgable Windows people.

Move `std::memchr` to `sys_common`

`std::memchr` is a thin abstraction over the different `memchr` implementations in `sys`, along with documentation and tests. The module is only used internally by `std`, nothing is exported externally. Code like this is exactly what the `sys_common` module is for, so this PR moves it there.

…ou-se

Expose `Concurrent` (private type in public i'face)

rust-lang#53410 introduced experimental support for custom test frameworks.

Such frameworks may wish to build upon `library/test` by calling into its publicly exposed API (which I entirely understand is wholly unstable).  However, any that wish to call `test::run_test` cannot currently do so because `test::options::Concurrent` (the type of its `concurrent` parameter) is not publicly exposed.

…=jonas-schievink

⬆️ rust-analyzer

…gisa

PassWrapper: update for LLVM change D102093

In https://reviews.llvm.org/D102093 lots of things stopped taking the
DebugLogging boolean parameter. Mercifully we appear to always set
DebugPassManager to false, so I don't think we're losing anything by not
passing this parameter.

…_type, r=davidtwco

Add diagnostic item to `CStr`

Required for clippy issue: rust-lang/rust-clippy#7145

…=dtolnay

Fix UB in documented example for `ptr::swap`

Compare [this (short) discussion on zulip](https://rust-lang.zulipchat.com/#narrow/stream/122651-general/topic/Pointers.20to.20overlapping.20arrays) (or [in the archive](https://zulip-archive.rust-lang.org/122651general/92017Pointerstooverlappingarrays.html), if you don’t have an account).

`@rustbot` label T-doc T-libs

Fix invalid CSS rules for a:hover

When hovering some links:

![Screenshot from 2021-05-19 15-00-31](https://user-images.githubusercontent.com/3050060/118823585-5f2a4b80-b8b9-11eb-8043-bb7759a178c7.png)
![Screenshot from 2021-05-19 15-00-29](https://user-images.githubusercontent.com/3050060/118823566-5b96c480-b8b9-11eb-8c4e-08e490752fbf.png)

It is a side-effect from rust-lang#84462.

r? ``@jsha``

CTFE Machine: do not expose Allocation

`Memory` is careful now to not expose direct access to `Allocation`, but this one slipped through.
r? `@oli-obk`