This test has recently been failing on the bots, and I'm not entirely sure why.
I haven't been able to reproduce locally or on the bots, so I'm adding some
messages to help diagnose the problem hopefully.

This reverts commit 40b9f5de.

This reverts commit df2f1fa7.

This reverts commit 95cfc356.

This reverts commit 6e0611a4.

Removes an unnecessary allocation when passing the command line arguments to the librustc driver.

Fixes #17662.

This was originally part of #17215.

Closes #15506.
Closes #15630.
Closes #17263.

This also partially implements #15838.

cc #17627 

cc @aturon 

r? anyone?

Previously it output `partially moved` to eagerly. This updates it to be more
accurate and output `collaterally moved` for use of values that were invalidated
by moves out of different fields in the same struct.

Closes #15630.

Additionally, support zero-sized types.

Now there isn't a safe interface of `PartialVec` anymore, it's just a bare data structure with destructor that assumes you handled everything correctly before.

[breaking-change]

If you are using slicing syntax you will need to add #![feature(slicing_syntax)] to your crate.

Deprecates slicing methods from ImmutableSlice/MutableSlice in favour of slicing syntax or the methods in Slice/SliceMut.

Closes #17273.

Closes #17263.

Closes #15506.

This PR begins the process of [runtime removal](https://github.com/rust-lang/rfcs/pull/230) by dismantling the `librustuv` crate and associated event loop.

The result is that, while `libgreen` can still be used for task scheduling purposes, it will no longer be feasible to use green-threaded I/O.

Removing the libuv-based event loop eases the transition away from the runtime system, which will be done incrementally.

In terms of visible API changes, this PR:

* Removes `std::io::signal`, which was never implemented on the native threading model.

* Removes the `iotest!` macro, which was previously used to run I/O tests on both green and native threading models.

* Removes the `green_start!` macro for starting an application with a `librustuv` event loop.

* Removes the `librustuv` crate itself.

It also removes the `libuv` and `gyp` submodules and adjusts the build system and copyright notices accordingly.

If you wish to continue using `librustuv` and green-threaded I/O, consider using [green-rs](https://github.com/alexcrichton/green-rs/), which provides its own I/O stack.

The `std::io::signal` API was only implemented under `librustuv`, which
is now being removed. Rather than keep around an unimplemented API, this
commit removes it altogether.

See the [runtime removal
RFC](https://github.com/rust-lang/rfcs/pull/230) for more context.

See [green-rs](https://github.com/alexcrichton/green-rs/) for a possible
migration path for signal handling code, although in the long run we
plan to add native signal handling to `std::io`.

[breaking-change]

This commit removes the libuv and gyp submodules, as well as all build
infrastructure related to them.

For more context, see the [runtime removal
RFC](https://github.com/rust-lang/rfcs/pull/230)

[breaking-change]

This is a patch for #17628, thanks to @kmcallister for your helpful hints!

This commit removes the `librustuv` crate.

See the [runtime removal
RFC](https://github.com/rust-lang/rfcs/pull/230) for more context.

See [green-rs](https://github.com/alexcrichton/green-rs/) for a possible
migration path if you wish to continue using green-threaded I/O. The
library provides its own I/O API surface.

[breaking-change]

This commit removes the `iotest!` macro from `std::io`. The macro was
primarily used to ensure that all io-related tests were run on both
libnative and libgreen/librustuv. However, now that the librustuv stack
is being removed, the macro is no longer needed.

See the [runtime removal
RFC](https://github.com/rust-lang/rfcs/pull/230) for more context.

[breaking-change]

Closes #17627

In some build environments (such as chrooted Nix builds), `env` can only
be found in the explicitly-provided PATH, not in default places such as
/bin or /usr/bin. So we need to pass-through PATH when spawning the
`env` sub-process.

Fixes #17617

There is more that could be done, but this was the low hanging fruit.

Fixes that unit-like structs cannot be used if they are re-exported and used in another crate. (ICE)
The relevant changes are in `rustc::metadata::{decoder, encoder}` and `rustc::middle::ty`.

A test case is included.

The problem is that the expressoin `UnitStruct` is an `ExprPath` to an `DefFn`, which is of expr kind `RvalueDatumExpr`, but for unit-struct ctors the expr kind should be `RvalueDpsExpr`. I fixed this (in a I guess clean way) by introducing `CtorFn` in the metadata and including a `is_ctor` flag in `DefFn`.

Closes #17490

prefer `Deref` over `DerefMut` in all other circumstances.

Because the compiler now prefers `Deref`, this can break code that
looked like:

    let mut foo = bar.borrow_mut();
    (*foo).call_something_that_requires_mutable_self();

Replace this code with:

    let mut foo = bar.baz();
    (&mut *foo).call_something_that_requires_mutable_self();

Closes #12825.

[breaking-change]

r? @nikomatsakis

This bound is already implicit through the AnyPrivate trait,
but since it is not explicit, you still have to write Box<Any + 'static>,
even though Any can only be 'static.

Introducing the 'static bound here makes this bound explicit, making
Box<Any> legal.

This breaks code that looks like:

    match foo {
        1..3 => { ... }
    }

Instead, write:

    match foo {
        1...3 => { ... }
    }

Closes #17295.

r? @nick29581 

This bound is already implicit through the AnyPrivate trait,
but since it is not explicit, you still have to write Box<Any + 'static>,
even though Any can only be 'static.

Introducing the 'static bound here makes this bound explicit, making
Box<Any> legal.

In some build environments (such as chrooted Nix builds), `env` can only
be found in the explicitly-provided PATH, not in default places such as
/bin or /usr/bin. So we need to pass-through PATH when spawning the
`env` sub-process.

Fixes #17617