See rust-lang/rust#34761.

Discussion can be found on rust-lang/rust#41620.

See rust-lang/rust#53857.

that is, I suspect it should be retired because it is testing behavior
(namely a `#[repr(C)] struct Empty;`) that, if I understand correctly,
is undefined.

See also rust-lang/rust#53859.

See also rust-lang/rust#53858.

(I may have accidentally added it to some auxilliary crates as well;
my emacs-macro-based methodology was pretty crude.)

fix `is_non_exhaustive` confusion between structs and enums

Structs and enums can both be non-exhaustive, with a very different
meaning. This PR splits `is_non_exhaustive` to 2 separate functions - 1
for structs, and another for enums, and fixes the places that got the
usage confused.

Fixes #53549.

r? @EddyB

rustbuild: Tweak LLVM distribution layout

This commit tweaks the layout of a few components that we distribute to
hopefully fix across all platforms the recent issues with LLD being unable to
find the LLVM shared object. In #53245 we switched to building LLVM as a dynamic
library, which means that LLVM tools by default link to LLVM dynamically rather
than statically. This in turn means that the tools, at runtime, need to find the
LLVM shared library.

LLVM's shared library is currently distributed as part of the rustc component.
This library is located, however, at `$sysroot/lib`. The LLVM tools we ship are
in two locations:

* LLD is shipped at `$sysroot/lib/rustlib/$host/bin/rust-lld`
* Other LLVM tools are shipped at `$sysroot/bin`

Each LLVM tool has an embedded rpath directive indicating where it will search
for dynamic libraries. This currently points to `../lib` and is presumably
inserted by LLVM's build system. Unfortunately, though, this directive is only
correct for the LLVM tools at `$sysroot/bin`, not LLD!

This commit is targeted at fixing this situation by making two changes:

* LLVM tools other than LLD are moved in the distribution to
  `$sysroot/lib/rustlib/$host/bin`. This moves them next to LLD and should
  position them for...
* The LLVM shared object is moved to `$sysroot/lib/rustlib/$host/lib`

Together this means that all tools should natively be able to find the shared
object and the shared object should be installed all the time for the various
tools. Overall this should...

Closes #53813

Add trim_start, trim_end etc.; deprecate trim_left, trim_right, etc. in future

Adds the methods: `trim_start`, `trim_end`, `trim_start_matches` and `trim_end_matches`.
Deprecates `trim_left`, `trim_right`, `trim_left_matches` and `trim_right_matches` starting from Rust 1.33.0, three versions from when they'll initially be marked as being deprecated, using the future deprecation from https://github.com/rust-lang/rust/issues/30785 and https://github.com/rust-lang/rust/pull/51681.

Fixes https://github.com/rust-lang/rust/issues/30459.

ThinLTO: Don't keep files open after mmaping them.

Fixes #53947.

r? @alexcrichton

Restore lldb build

commit 6c101422 ("Update LLVM submodule") disabled the lldb build.
This patch updates the lldb and clang submodules to once again build
against the LLVM that is included in the Rust tree, and reverts the
.travis.yml changes from that patch.

This commit tweaks the layout of a few components that we distribute to
hopefully fix across all platforms the recent issues with LLD being unable to
find the LLVM shared object. In #53245 we switched to building LLVM as a dynamic
library, which means that LLVM tools by default link to LLVM dynamically rather
than statically. This in turn means that the tools, at runtime, need to find the
LLVM shared library.

LLVM's shared library is currently distributed as part of the rustc component.
This library is located, however, at `$sysroot/lib`. The LLVM tools we ship are
in two locations:

* LLD is shipped at `$sysroot/lib/rustlib/$host/bin/rust-lld`
* Other LLVM tools are shipped at `$sysroot/bin`

Each LLVM tool has an embedded rpath directive indicating where it will search
for dynamic libraries. This currently points to `../lib` and is presumably
inserted by LLVM's build system. Unfortunately, though, this directive is only
correct for the LLVM tools at `$sysroot/bin`, not LLD!

This commit is targeted at fixing this situation by making two changes:

* LLVM tools other than LLD are moved in the distribution to
  `$sysroot/lib/rustlib/$host/bin`. This moves them next to LLD and should
  position them for...
* The LLVM shared object is moved to `$sysroot/lib/rustlib/$host/lib`

Together this means that all tools should natively be able to find the shared
object and the shared object should be installed all the time for the various
tools. Overall this should...

Closes #53813

rustc: Prepare the `atomics` feature for wasm

This commit adds a few changes for atomic instructions on the
`wasm32-unknown-unknown` target. Atomic instructions are not yet stable in
WebAssembly itself but there are multiple implementations and LLVM has support
for the proposed instruction set, so let's work on exposing it!

Here there are a few inclusions:

* The `atomics` feature was whitelisted for LLVM, allowing code in Rust to
  enable/disable/gate on this.

* The `singlethread` option is turned off for wasm when the `atomics` feature is
  enabled. This means that by default wasm won't be lowering with atomics, but
  when atomics are enabled globally we'll turn off single-threaded mode to
  actually codegen atomics. This probably isn't what we'll want in the long term
  but for now it should work.

* Finally the maximum atomic width is increased to 64 to reflect the current
  wasm spec.

Make json test output formatter represent "test_count" as num

fixes #53866

Introduce Custom Test Frameworks

Introduces `#[test_case]` and `#[test_runner]` and re-implements `#[test]` and `#[bench]` in terms of them.

Details found here: https://blog.jrenner.net/rust/testing/2018/08/06/custom-test-framework-prop.html

Update Cargo.lock

This also includes major version bumps for the rand crate used by core, std, and alloc tests, among other crates (regex, etc.) used elsewhere. Since these are all internal there should be no user-visible changes.

r? @alexcrichton

Allow to check if sync::Once is already initialized

Hi!

I propose to expose a way to check if a `Once` instance is initialized.

I need it in `once_cell`. `OnceCell` is effetively a pair of `(Once, UnsafeCell<Option<T>>)`, which can set the `T` only once. Because I can't check if `Once` is initialized, I am forced to add an indirection and check the value of ptr instead:

https://github.com/matklad/once_cell/blob/8127a81976c3f2f4c0860562c3f14647ebc025c0/src/lib.rs#L423-L429

https://github.com/matklad/once_cell/blob/8127a81976c3f2f4c0860562c3f14647ebc025c0/src/lib.rs#L457-L461

The `parking_lot`'s version of `Once` exposes the state as an enum: https://docs.rs/parking_lot/0.6.3/parking_lot/struct.Once.html#method.state.

I suggest, for now, just to add a simple `bool` function: this fits my use-case perfectly, exposes less implementation details, and is forward-compatible with more fine-grained state checking.

commit 6c101422 ("Update LLVM submodule") disabled the lldb build.
This patch updates the lldb and clang submodules to once again build
against the LLVM that is included in the Rust tree, and reverts the
.travis.yml changes from that patch.

Update RLS and Rustfmt

RLS
* Allow project model to download crates ([#1020](https://github.com/rust-lang-nursery/rls/pull/1020))
* Support simple external builds ([#988](https://github.com/rust-lang-nursery/rls/pull/988))
* Support using external Rustfmt ([#990](https://github.com/rust-lang-nursery/rls/pull/990))

Rustfmt (0.99.4)
* Format chains with comment ([#2899](https://github.com/rust-lang-nursery/rls/pull/2899))
* Do not show wildcard pattern in slice pattern ([#2912](https://github.com/rust-lang-nursery/rls/pull/2912))
* Impl only use ([#2951](https://github.com/rust-lang-nursery/rls/pull/2951))
* ... and [more](https://github.com/rust-lang-nursery/rustfmt/compare/5c9a2b6c13d3b6f8d3f9c02b130bb4b54fd489fb...1c408818c8a752dd584e7858b4afd3ceb011a7da)

Bumped in tandem to pull a single version of `rustc-ap-*` libs.

r? @nrc

This pulls the same version of rustc-ap-* libs as RLS does.

Link to more detailed docs in `slice::from_raw_parts_mut`

A few cleanups and minor improvements to save_analysis

- calculate the capacity of some `Vec`s
- change`to_owned()` to `clone()` for the purposes of `lower_attributes`
- remove a superfluous `clone()`
- prefer `to_owned()` to `to_string()`
- a few other minor improvements

miri engine: make sure we do not copy unsized data

r? @oli-obk