The atomic equivalent of Cell::from_mut.

…brary

Fixes 76271

These tests are about the standard library, not the compiler itself, thus should live in `library`, see rust-lang#76268.

Move:
 - `src\test\ui\consts\const-nonzero.rs` to `library\core`
 - `src\test\ui\consts\ascii.rs` to `library\core`
 - `src\test\ui\consts\cow-is-borrowed` to `library\alloc`

Part of rust-lang#76268

If two features are defined as incompatible, using them together would
result in an error

Co-authored-by: Joshua Nelson <joshua@yottadb.com>

I believe the documentation is currently a little misleading.

For example, in the docs for `filter()`:

> If the closure returns `false`, it will try again, and call the closure on
> the next element, seeing if it passes the test.

This kind of implies that if the closure returns true then we *don't* "try
again" and no further elements are considered. In actuality that's not the
case, every element is tried regardless of what happened with the previous
element.

This change tries to clarify that by removing the uses of "try again"
altogether.

cdb chokes on the cast and reports "Unable to find type 'tuple<u64,u64> *' for cast."

…m-mut, r=KodrAus

Add Atomic*::from_mut.

The atomic equivalent of [`Cell::from_mut`](https://doc.rust-lang.org/stable/std/cell/struct.Cell.html#method.from_mut).

Try to improve the documentation of `filter()` and `filter_map()`.

I believe the documentation is currently a little misleading.

For example, in the docs for `filter()`:

> If the closure returns `false`, it will try again, and call the closure on
> the next element, seeing if it passes the test.

This kind of implies that if the closure returns true then we *don't* "try
again" and no further elements are considered. In actuality that's not the
case, every element is tried regardless of what happened with the previous
element.

This change tries to clarify that by removing the uses of "try again"
altogether.

…racking_issue, r=joshtriplett

Update tracking issue for const_caller_location

Update the tracking issue to rust-lang#76156, as suggested in rust-lang#76105.

Add missing link in README

Move some Vec UI tests into alloc unit tests

A bit of work towards rust-lang#76268, makes a number of the Vec UI tests that are simply running code into unit tests. Ensured that they are being run when testing liballoc locally.

Allow try blocks as the argument to return expressions

Fixes rust-lang#76271

I don't think this needs to be edition-aware (phew) since `return try` in 2015 is also the start of an expression, just with a struct literal instead of a block (`return try { x: 4, y: 5 }`).

Remove an unnecessary allowed lint

It is outdated.

…, r=lcnr

Implementation of incompatible features error

Proposal of a new error: Incompatible features

This error should happen if two features which are not compatible are used together.

For now the only incompatible features are `const_generics` and `min_const_generics`

fixes rust-lang#76280

Make `Ipv4Addr` and `Ipv6Addr` const tests unit tests under `library`

These tests are about the standard library, not the compiler itself, thus should live in `library`, see rust-lang#76268.

Address review comments on `Peekable::next_if`

r? @pickfire
See rust-lang#72310 (review) for context.

Link to `#capacity-and-reallocation` when using with_capacity

Follow up to rust-lang#76058 (comment).
r? @pickfire

Move various ui const tests to `library`

Move:
 - `src\test\ui\consts\const-nonzero.rs` to `library\core`
 - `src\test\ui\consts\ascii.rs` to `library\core`
 - `src\test\ui\consts\cow-is-borrowed` to `library\alloc`

Part of rust-lang#76268

r? @matklad

Indent a note to make folding work nicer

Sublime Text folds code based on indentation. It maybe an unnecessary change, but does it look nicer after that ?

time.rs: Make spelling of "Darwin" consistent

On line 89 of this file, the OS name is written as "Darwin", but on line 162 it is written in all-caps. Darwin is usually spelt as a standard proper noun, i.e. "Darwin", rather than in all-caps.

This change makes that form consistent in both places.

…ic-morse

Use ops::ControlFlow in rustc_data_structures::graph::iterate

Since I only know about this because you mentioned it,
r? @ecstatic-morse

If we're not supposed to use new `core` things in compiler for a while then feel free to close, but it felt reasonable to merge the two types since they're the same, and it might be convenient for people to use `?` in their traversal code.

(This doesn't do the type parameter swap; NoraCodes has signed up to do that one.)

…ibrary, r=matklad

Move Vec slice UI tests in library

Moved some of Vec slice UI tests in Library as a part of rust-lang#76268

r? @matklad

add some intra-doc links to `Iterator`

…=petrochenkov

debuginfo:  Ignore HashMap .natvis tests before cdb 10.0.18362.1

CDB <10.0.18362.1 chokes on casts within HashMap's natvis visualizers.  This PR adds support for "min-cdb-version" (per existing "min-gdb-version" and "min-lldb-version" filters) and uses it.  CI uses a more recent version of CDB for testing and thus should still run the tests.

Credit to @petrochenkov per rust-lang#76352 for helping catch this.

### SDK Testing

| Win 10 SDK                                                             |  x64 CDB          | rustc 1.47.0-nightly (bf43421 2020-08-25) built-in .natvis  | Note |
| --------------------------------------------------------------------- | ----------------- | ------------------------------------------------------------- | ---- |
| [10.0.19041.0](https://go.microsoft.com/fwlink/p/?linkid=2120843)     | 10.0.19041.1      | ✔️                                                            | CI
| [10.0.18362.1](https://go.microsoft.com/fwlink/?linkid=2083338)       | 10.0.18362.1      | ✔️                                                            | MaulingMonkey
| [10.0.17763.0](https://go.microsoft.com/fwlink/p/?LinkID=2033908)     | 10.0.17763.132    | ❌ `Unable to find type 'tuple<u64,u64> *' for cast.`
| [10.0.17134.12](https://go.microsoft.com/fwlink/p/?linkid=870807)     | 10.0.17134.12     | ❌ `Unable to find type 'tuple<u64,u64> *' for cast.`
| [10.0.16299.91](https://go.microsoft.com/fwlink/p/?linkid=864422)     | 10.0.16299.91     | ❌ `Unable to find type 'tuple<u64,u64> *' for cast.`
| [10.0.15063.468](https://go.microsoft.com/fwlink/p/?LinkId=845298)    | 10.0.15063.468    | ❌ `Unable to find type 'tuple<u64,u64> *' for cast.`
| [10.0.14393.795](https://go.microsoft.com/fwlink/p/?LinkId=838916)    | 10.0.14321.1024   | ❌ `Unable to find type 'tuple<u64,u64> *' for cast.` | petrochenkov
| [10.0.10586.212](https://go.microsoft.com/fwlink/p/?LinkID=698771)    | 10.0.10586.567    | ❌ `Expected ')' at '+ 1)].__1'`
| [10.0.10240](https://go.microsoft.com/fwlink/p/?LinkId=619296)        | 10.0.10240?       | ❔ Untested

### Rust Testing

```cmd
x.py test --stage 1 src/tools/tidy
x.py test --stage 1 --build x86_64-pc-windows-msvc src\test\debuginfo
```

Also verified test still fails when intentionally broken w/ CDB version >= min-cdb-version.