RFC rust-lang#2195 specifies that a repr(int) enum such as:

    #[repr(u8)]
    enum MyEnum {
        B { x: u8, y: i16, z: u8 },
    }

has a layout that is equivalent to:

    #[repr(C)]
    enum MyEnumVariantB { tag: u8, x: u8, y: i16, z: u8 },

However this isn't actually implemented, with the actual layout being
roughly equivalent to:

    union MyEnumPayload {
        B { x: u8, y: i16, z: u8 },
    }

    #[repr(packed)]
    struct MyEnum {
        tag: u8,
        payload: MyEnumPayload,
    }

Thus the variant payload is *not* subject to repr(C) ordering rules, and
gets re-ordered as `{ x: u8, z: u8, z: i16 }`

The existing tests added in pull-req rust-lang#45688 fail to catch this as the
repr(C) ordering just happens to match the current Rust ordering in this
case; adding a third field reveals the problem.

This commit updates from LLVM 7.0.0 to git revisions of clang/llvm/lld
to build LLVM on our dist builders for Linux. The goal of this is to
fix rust-lang#56849 by picking up a fix [1] in LLD.

Closes rust-lang#56849

[1]: llvm-mirror/lld@3be4e82

Layout size overflow and typeck eval errors are reported. Trigger a bug
only when the eval error is strictly labeled as TooGeneric.

…the values

This is done by adding a new `IsJoint` field to `TokenStream::Tree`,
which simplifies a lot of `match` statements. And likewise for
`CursorKind`.

The commit also adds a new method `TokenTree:stream()` which can replace
a choice between `.into()` and `.joint()`.

Closes rust-lang#41758

Add DoubleEndedIterator::nth_back

As suggested by rust-lang#54054. This doesn't fix that issue, as this doesn't add enough implementations to optimise that specific use case, but it adds the method and a few (relatively) trivial overrides to work as an initial implementation.

It's probably going to be a lot of work adding `nth_back` implementations everywhere, and I don't have the time to include it all in this commit. But, it's a start. :)

…chton

Add unstable VecDeque::rotate_{left|right}

Like the ones on slices, but more efficient because vecdeque is a circular buffer.

Issue that proposed this: rust-lang#56686

~~:bomb: Please someone look very carefully at the `unsafe` in this!  The `wrap_copy` seems to be exactly what this method needs, and the `len` passed to it is never more than half the length of the deque, but I haven't managed to prove to myself that it's correct :bomb:~~ I think I proved that this code meets the requirement of the unsafe code it's calling; please double-check, of course.

…, r=QuietMisdreavus

Reduce search-index.js size

Coming from:

```
1735683 Dec 16 01:35 build/x86_64-apple-darwin/doc/search-index.js
```

to:

```
727755 Dec 16 01:51 build/x86_64-apple-darwin/doc/search-index.js
```

r? @QuietMisdreavus

Disable field reordering for repr(int).

This fixes the problem that the test in rust-lang#56619 uncovers.

Closes rust-lang#56619.

…rister

rustc: Update Clang used to build LLVM on Linux

This commit updates from LLVM 7.0.0 to git revisions of clang/llvm/lld
to build LLVM on our dist builders for Linux. The goal of this is to
fix rust-lang#56849 by picking up a fix [1] in LLD.

Closes rust-lang#56849

[1]: llvm-mirror/lld@3be4e82

static eval: Do not ICE on layout size overflow

Layout size overflow and typeck eval errors are reported. Trigger a bug
only when the eval error is strictly labeled as TooGeneric.

Fixes: rust-lang#56762

Ignore ui/target-feature-gate on sparc, sparc64, powerpc, powerpc64 and powerpc64le

The test ui/target-feature-gate is not applicable on sparc, sparc64, powerpc, powerpc64 and powerpc64le and consequently fails there. So just ignore it on these targets.

Simplify MIR generation for logical operations

Reduces one block and one branch from MIR generated for a logical operator.

…fJung

Remove a wrong multiplier on relocation offset computation

r? @RalfJung

fixes rust-lang#56800

…lacrum

Add --progress to git submodule commands in x.py

This is a relatively new flag, but it means that git will indicate the progress of the update as it would with regular clones. This is especially helpful as some of the submodules are really big and it's difficult to tell if it's hanging or still updating.

…res, r=QuietMisdreavus

deny intra-doc link resolution failures in libstd

Fixes rust-lang#56693.

Until we land a fix for the underlying issue (rust-lang#56922), we can at least fix the failures in libstd so they don't propagate to downstream crates.

…petrochenkov

Remove `TokenStream::JointTree`.

This is done by adding a new `IsJoint` field to `TokenStream::Tree`,
which simplifies a lot of `match` statements. And likewise for
`CursorKind`.

The commit also adds a new method `TokenTree:stream()` which can replace
a choice between `.into()` and `.joint()`.

…r=Manishearth

Mem uninit doc ptr drop

Extend the mem::uninitialized documentation to account for partially initialized arrays and how to correctly handle these. These are used in some datastructures (trees for example) or in FFI.

r? @Manishearth

make basic CTFE tracing available on release builds

Debugging things going wrong in miri is currently pretty much impossible with a nightly Rust.

r? @oli-obk

…nd-support, r=alexcrichton

Adding unwinding support for x86_64_fortanix_unknown_sgx target.

Unwinding support is provided by our port of LLVM's libunwind which is available from https://github.com/fortanix/libunwind/tree/release_50.

libunwind requires support for rwlock and printing to stderr, which is only provided by `std` for this target. This poses two problems: 1) how to expose the `std` functionality to C and 2) dependency inversion.

### Exposing `std`

For exposing the functionality we chose to expose the following symbols:

* __rust_rwlock_rdlock
* __rust_rwlock_wrlock
* __rust_rwlock_unlock
* __rust_print_err
* __rust_abort

Also, the following are needed from `alloc`:

* __rust_alloc
* __rust_dealloc

#### Rust RWLock in C

In `libunwind`, RWLock is initialized as a templated static variable:

```c
pthread_rwlock_t DwarfFDECache<A>::_lock = PTHREAD_RWLOCK_INITIALIZER;
```

I don't know of a good way to use the Rust sys::rwlock::RWLock type and initializer there. We could have a static global variable in Rust, but that doesn't work with the templating. The variable needs to be initialized statically, since this target doesn't support the .init section. Currently, I just used a byte array and standard C array initialization. The mapping between this C type and the Rust type needs to be manually maintained. There is a compile-time check and a unit test to make sure the Rust versions of these C definitions match the actual Rust type. If any reviewer knows of a better solution, please do tell.

### Dependency inversion issue

`std` depends on `panic_unwind` which depends on `libunwind`, and `libunwind` depends on `std`. This is not normally supported by Rust's linking system. Therefore we use raw C exports from `std` *and* `libunwind.a` is linked last in the target `post_link_objects` instead of being built as part of the Rust `libunwind`. Currently, all C exports are defined in `src/libstd/sys/sgx/rwlock.rs` to overcome LTO issues. Only the `__rust_rwlock_*` definitions *need* to live there for privacy reasons. Once again, if any reviewer knows of a better solution, please do tell.

r? @alexcrichton

…li-obk

miri: allocation is infallible

…i-obk

A few tweaks to dropck_outlives

- remove an unnecessary call to `cloned()`
- simplify common patterns

…ations, r=Mark-Simulacrum

Fix compiletest `trim` deprecation warnings

None

…li-obk

suggest similar lint names for unknown lints

Fixes rust-lang#54737.

…kruppe

Stabilize Vec(Deque)::resize_with

Closes rust-lang#41758