This commit introduses 2 methods under "str_split_as_str" gate with common
signature of `&Split<'a, _> -> &'a str'`. Both of them work like
`Chars::as_str` - return unyield part of the inner string.

…r` methods

This commit entroduce 4 methods smililar to `Split::as_str` all under the same
gate "str_split_as_str".

This commit entroduces `core::str::SplitInclusive::as_str` method similar to
`core::str::Split::as_str`, but under different gate -
"str_split_inclusive_as_str" (this is done so because `SplitInclusive` is
itself unstable).

This function was renamed.

For sub-items on a page don't show cfg that has already been rendered on
a parent item. At its simplest this means not showing anything that is
shown in the portability message at the top of the page, but also for
things like fields of an enum variant if that variant itself is
cfg-gated then don't repeat those cfg on each field of the variant.

This does not touch trait implementation rendering, as that is more
complex and there are existing issues around how it deals with doc-cfg
that need to be fixed first.

…ack message when RUST_BACKTRACE=0

…ack message when RUST_BACKTRACE=0

The comment said it's UB to call lock() while it is locked. That'd be
quite a useless Mutex. :) It was supposed to say 'locked by the same
thread', not just 'locked'.

StaticMutex is only ever used with as a static (as the name already
suggests). So it doesn't have to be generic over a lifetime, but can
simply assume 'static.

This 'static lifetime guarantees the object is never moved, so this is
no longer a manually checked requirement for unsafe calls to lock().

This commit adjust `#[rustc_symbol_name]` so that it can be applied to
non-monomorphic functions without producing an ICE.

Signed-off-by: David Wood <david@davidtw.co>

This commit modifies v0 symbol mangling to include all generic
parameters from impl blocks (not just those used in the self type).

Signed-off-by: David Wood <david@davidtw.co>

ensure arguments are included in count mismatch span

The current diagnostic isn't very helpful if the function header spans multiple lines. Lines comprising the function signature may be elided to keep the diagnostic short, but these lines are essential to fixing the error. This is made worse when the function has a body, because the last two lines of the span are then dedicated to showing the end of the body, which is irrelevant.

This PR changes the span to be a multispan made up of the header and the the arguments, ensuring they won't be elided. It also discards the function body from the span.

[Old](https://play.rust-lang.org/?version=stable&mode=debug&edition=2018&gist=f92d9f81a8c9416f0f04e4e09923b6d4):

```
error[E0061]: this function takes 6 arguments but 1 argument was supplied
  --> src/main.rs:18:5
   |
1  | / fn bar(
2  | |     a: i32,
3  | |     b: i32,
4  | |     c: i32,
...  |
14 | |     println!("{}", f);
15 | | }
   | |_- defined here
...
18 |       bar(1);
   |       ^^^ - supplied 1 argument
   |       |
   |       expected 6 arguments
```

New:

```
error[E0061]: this function takes 6 arguments but 1 argument was supplied
  --> $DIR/not-enough-arguments.rs:28:3
   |
LL |   bar(1);
   |   ^^^ - supplied 1 argument
   |   |
   |   expected 6 arguments
   |
note: function defined here
  --> $DIR/not-enough-arguments.rs:9:1
   |
LL | / fn bar(
LL | |     a: i32,
   | |     ^^^^^^^
LL | |     b: i32,
   | |     ^^^^^^^
LL | |     c: i32,
   | |     ^^^^^^^
LL | |     d: i32,
   | |     ^^^^^^^
LL | |     e: i32,
   | |     ^^^^^^^
LL | |     f: i32,
   | |     ^^^^^^^
LL | | ) {
   | |_^
```

…olnay

Add `str::{Split,RSplit,SplitN,RSplitN,SplitTerminator,RSplitTerminator,SplitInclusive}::as_str` methods

tl;dr this allows viewing unyelded part of str-split-iterators, like so:
```rust
let mut split = "Mary had a little lamb".split(' ');
assert_eq!(split.as_str(), "Mary had a little lamb");
split.next();
assert_eq!(split.as_str(), "had a little lamb");
split.by_ref().for_each(drop);
assert_eq!(split.as_str(), "");
```

--------------

This PR adds semi-identical `as_str` methods to most str-split-iterators with signatures like `&'_ Split<'a, P: Pattern<'a>> -> &'a str` (Note: output `&str` lifetime is bound to the `'a`, not the `'_`). The methods are similar to [`Chars::as_str`]

`SplitInclusive::as_str` is under `"str_split_inclusive_as_str"` feature gate, all other methods are under `"str_split_as_str"` feature gate.

Before this PR you had to sum `len`s of all yielded parts or collect into `String` to emulate `as_str`.

[`Chars::as_str`]: https://doc.rust-lang.org/core/str/struct.Chars.html#method.as_str

…ms, r=eddyb

mangling: mangle impl params w/ v0 scheme

This PR modifies v0 symbol mangling to include all generic parameters from impl blocks (not just those used in the self type) - an alternative fix to rust-lang#75326.

```
original:
   _RNCNvXCs4fqI2P2rA04_19impl_param_manglingINtB4_3FooppENtNtNtNtCsfnEnqCNU58Z_4core4iter6traits8iterator8Iterator4next0B4_
//        |------------ B4_ ----------------|
// _R (N C (N v (X (C ((s 4fqI2p2rA04_) 19impl_param_mangling)) (I (N t B4_ 3Foo) pp E) (N t (N t (N t (N t (C ((s fnEnqCNU58Z_) 4core)) 4iter) 6traits) 8iterator) 8Iterator)) 4next) 0) B4_

modified:
   _RNvXINICs4fqI2P2rA04_11issue_753260pppEINtB5_3FooppENtNtNtNtCsfnEnqCNU58Z_4core4iter6traits8iterator8Iterator4nextB5_
// _R (N v (X (I (N I (C ((s 4fqI2P2rA04_) 11issue_75326)) 0) ppp E) (I (N t B5_ 3Foo) pp E) (N t (N t (N t (N t (C ((s fnEnqCNU58Z_) 4core)) 4iter) 6traits) 8iterator) 8Iterator)) 4next) B5_
//            |     ^                                              |
//            |     |                                              |
//            |     new impl namespace                             |
```

~~Submitted as a draft as after some discussion w/ @eddyb, I'm going to do some investigation into (yet more alternative) changes to polymorphization that might remove the necessity for this.~~

r? @eddyb

Refactor io/buffered.rs into submodules

This pull request splits `BufWriter`, `BufReader`, `LineWriter`, and `LineWriterShim` (along with their associated tests) into separate submodules. It contains no functional changes. This change is being made in anticipation of adding another type of buffered writer which can be switched between line- and block-buffering mode.

Part of a series of pull requests resolving rust-lang#60673.

…n, r=nikomatsakis

Stabilize move_ref_pattern

# Implementation
- Initially the rule was added in the run-up to 1.0. The AST-based borrow checker was having difficulty correctly enforcing match expressions that combined ref and move bindings, and so it was decided to simplify forbid the combination out right.
- The move to MIR-based borrow checking made it possible to enforce the rules in a finer-grained level, but we kept the rule in place in an effort to be conservative in our changes.
- In rust-lang#68376, @Centril lifted the restriction but required a feature-gate.
- This PR removes the feature-gate.

Tracking issue: rust-lang#68354.

# Description
This PR is to stabilize the feature `move_ref_pattern`, which allows patterns
containing both `by-ref` and `by-move` bindings at the same time.

For example: `Foo(ref x, y)`, where `x` is `by-ref`,
and `y` is `by-move`.

The rules of moving a variable also apply here when moving *part* of a variable,
such as it can't be referenced or moved before.

If this pattern is used, it would result in *partial move*, which means that
part of the variable is moved. The variable that was partially moved from
cannot be used as a whole in this case, only the parts that are still
not moved can be used.

## Documentation
- The reference (rust-lang/reference#881)
- Rust by example (rust-lang/rust-by-example#1377)

## Tests
There are many tests, but I think one of the comperhensive ones:
- [borrowck-move-ref-pattern-pass.rs](https://github.com/Centril/rust/blob/85fbf49ce0e2274d0acf798f6e703747674feec3/src/test/ui/pattern/move-ref-patterns/borrowck-move-ref-pattern-pass.rs)
- [borrowck-move-ref-pattern.rs](https://github.com/Centril/rust/blob/85fbf49ce0e2274d0acf798f6e703747674feec3/src/test/ui/pattern/move-ref-patterns/borrowck-move-ref-pattern.rs)

# Examples

```rust
#[derive(PartialEq, Eq)]
struct Finished {}

#[derive(PartialEq, Eq)]
struct Processing {
    status: ProcessStatus,
}

#[derive(PartialEq, Eq)]
enum ProcessStatus {
    One,
    Two,
    Three,
}

#[derive(PartialEq, Eq)]
enum Status {
    Finished(Finished),
    Processing(Processing),
}

fn check_result(_url: &str) -> Status {
    // fetch status from some server
    Status::Processing(Processing {
        status: ProcessStatus::One,
    })
}

fn wait_for_result(url: &str) -> Finished {
    let mut previous_status = None;
    loop {
        match check_result(url) {
            Status::Finished(f) => return f,
            Status::Processing(p) => {
                match (&mut previous_status, p.status) {
                    (None, status) => previous_status = Some(status), // first status
                    (Some(previous), status) if *previous == status => {} // no change, ignore
                    (Some(previous), status) => { // Now it can be used
                        // new status
                        *previous = status;
                    }
                }
            }
        }
    }
}
```

Before, we would have used:
```rust
                match (&previous_status, p.status) {
                    (Some(previous), status) if *previous == status => {} // no change, ignore
                    (_, status) => {
                        // new status
                        previous_status = Some(status);
                    }
                }
```

Demonstrating *partial move*
```rust
fn main() {
    #[derive(Debug)]
    struct Person {
        name: String,
        age: u8,
    }

    let person = Person {
        name: String::from("Alice"),
        age: 20,
    };

    // `name` is moved out of person, but `age` is referenced
    let Person { name, ref age } = person;

    println!("The person's age is {}", age);

    println!("The person's name is {}", name);

    // Error! borrow of partially moved value: `person` partial move occurs
    //println!("The person struct is {:?}", person);

    // `person` cannot be used but `person.age` can be used as it is not moved
    println!("The person's age from person struct is {}", person.age);
}
```

…_the_top_of_the_query_stack, r=oli-obk

ICEs should always print the top of the query stack

see rust-lang#76920

…r, r=dtolnay

Use futex-based thread-parker for Wasm32.

This uses the existing `sys_common/thread_parker/futex.rs` futex-based thread parker (that was already used for Linux) for wasm32 as well (if the wasm32 atomics target feature is enabled, which is not the case by default).

Wasm32 provides the basic futex operations as instructions: https://webassembly.github.io/threads/syntax/instructions.html

These are now exposed from `sys::futex::{futex_wait, futex_wake}`, just like on Linux. So, `thread_parker/futex.rs` stays completely unmodified.

…-mutex, r=dtolnay

For backtrace, use StaticMutex instead of a raw sys Mutex.

The code used the very unsafe `sys::mutex::Mutex` directly, and built its own unlock-on-drop wrapper around it. The StaticMutex wrapper already provides that and is easier to use safely.

@rustbot modify labels: +T-libs +C-cleanup

…ex, r=dtolnay

Static mutex is static

StaticMutex is only ever used with as a static (as the name already suggests). So it doesn't have to be generic over a lifetime, but can simply assume 'static.

This 'static lifetime guarantees the object is never moved, so this is no longer a manually checked requirement for unsafe calls to lock().

@rustbot modify labels: +T-libs +A-concurrency +C-cleanup

…oudabi-sync, r=dtolnay

Cleanup cloudabi mutexes and condvars

This gets rid of lots of unnecessary unsafety.

All the AtomicU32s were wrapped in UnsafeCell or UnsafeCell<MaybeUninit>, and raw pointers were used to get to the AtomicU32 inside. This change cleans that up by using AtomicU32 directly.

Also replaces a UnsafeCell<u32> by a safer Cell<u32>.

@rustbot modify labels: +C-cleanup

Simplify doc-cfg rendering based on the current context

For sub-items on a page don't show cfg that has already been rendered on
a parent item. At its simplest this means not showing anything that is
shown in the portability message at the top of the page, but also for
things like fields of an enum variant if that variant itself is
cfg-gated then don't repeat those cfg on each field of the variant.

This does not touch trait implementation rendering, as that is more
complex and there are existing issues around how it deals with doc-cfg
that need to be fixed first.

### Screenshots, left is current, right is new:

![image](https://user-images.githubusercontent.com/81079/95387261-c2e6a200-08f0-11eb-90d4-0a9734acd922.png)

![image](https://user-images.githubusercontent.com/81079/95387458-06411080-08f1-11eb-81f7-5dd7f37695dd.png)

![image](https://user-images.githubusercontent.com/81079/95387702-6637b700-08f1-11eb-82f4-46b6cd9b24f2.png)

![image](https://user-images.githubusercontent.com/81079/95387905-b9aa0500-08f1-11eb-8d95-8b618d31d419.png)

![image](https://user-images.githubusercontent.com/81079/95388300-5bc9ed00-08f2-11eb-9ac9-b92cbdb60b89.png)

cc rust-lang#43781

…, r=oli-obk

rustc_parse: fix spans on cast and range exprs with attrs

Currently the span for cast and range expressions does not include the span of attributes associated to the lhs which is causing some issues for us in rustfmt.

```rust
fn foo() -> i64 {
    #[attr]
    1u64 as i64
}

fn bar() -> Range<i32> {
    #[attr]
    1..2
}
```

This corrects the span for cast and range expressions to fully include the span of child nodes

…ulacrum

BTreeMap: make PartialCmp/PartialEq explicit and tested

Follow-up on a topic raised in rust-lang#77612

r? @Mark-Simulacrum

Fix intra doc link for needs_drop

It currently links to itself. Oops.

r? @jyn514