We were recording stability attributes applied to fields in the
compiler, and even annotating it in the libs, but the compiler didn't
actually do the checks to give errors/warnings in user crates.

Details in the commit messages.

Implements `Debug`  for `RwLock` and `arc::Weak` in the same way it is implemented for `rc::Weak` (basically copy & paste).

The lack of this implementation prevents the automatic implementation of `Debug` for structs containing members of these types.

r? @alexcrichton
 
cc @nikomatsakis @pnkfelix 

Instead of allocating the same ports for ipv4 and ipv6 tests, instead draw all
ports from the same pool. Some tests connect to just "localhost" on a particular
port which may accidentally be interacting with other tests as the ipv-what-ness
isn't specified with the string "localhost"

Relevant logs:

* [Deadlock of the `net::tcp::tests::listen_localhost` test][mac]
* [Failure of the `fast_rebind` test][win1]
* [Failure of `multiple_connect_interleaved_lazy_schedule_ip4`][win2]

[mac]: https://gist.github.com/alexcrichton/349c7ce7c620c1adb2f2
[win1]: https://gist.github.com/alexcrichton/7e3611faae2e1edaee6f
[win2]: https://gist.github.com/alexcrichton/4f5f87749af3ad0f9851

Instead of allocating the same ports for ipv4 and ipv6 tests, instead draw all
ports from the same pool. Some tests connect to just "localhost" on a particular
port which may accidentally be interacting with other tests as the ipv-what-ness
isn't specified with the string "localhost"

Relevant logs:

* [Deadlock of the `net::tcp::tests::listen_localhost` test][mac]
* [Failure of the `fast_rebind` test][win1]
* [Failure of `multiple_connect_interleaved_lazy_schedule_ip4`][win2]

[mac]: https://gist.github.com/alexcrichton/349c7ce7c620c1adb2f2
[win1]: https://gist.github.com/alexcrichton/7e3611faae2e1edaee6f
[win2]: https://gist.github.com/alexcrichton/4f5f87749af3ad0f9851

rustdoc impl item did not include default methods for local crates, but did include them for external crates. This resulted in duplicate methods. Fix so that impl item does not include default methods for external crates.

Fix #22595.

unbreak openbsd/bitrig build after 2d200c9c (the complete build/check on openbsd is in progress)

@dhuseby maybe this one is in your list ?

In the process, also replaces two raw mutable pointers with `Unique` to
spell out the ownership semantics.

cc #22709

This needs to make it into the snapshot before #21824 can land.

r? @alexcrichton 

In the process, also replaces a raw mutable pointers with Unique to
spell out the ownership semantics.

cc #22709

The Path/PathBuf pair already implements the required `Borrow`/`ToOwned` traits and can be used in a `Cow` pointer, so why not?

r? @alexcrichton 

So it is symmetric to its `Iter` implementation. Also kills an FIXME.

The stability check checks the `PublicItems` map when giving errors if
there is a #[stable] item with a public contents that doesn't not have
its own stability. Without recording this, struct fields and enum
variants will not get errors for e.g. stable modules with unmarked
functions internally.

This is just improving the compiler's precision to give the standard
library developers more information earlier.

E.g.

    #![staged_api]
    #![feature(staged_api)]
    #![crate_type = "lib"]

    #[stable(feature = "rust1", since = "1.0.0")]
    pub struct Foo {
        pub x: i32
    }

    #[stable(feature = "rust1", since = "1.0.0")]
    pub mod bar {
        pub fn baz() {}
    }

Without the patch it gives:

    test.rs:12:5: 12:20 error: This node does not have a stability attribute
    test.rs:12     pub fn baz() {}
                   ^~~~~~~~~~~~~~~
    error: aborting due to previous error

With the patch it gives:

    test.rs:7:9: 7:15 error: This node does not have a stability attribute
    test.rs:7     pub x: i32
                      ^~~~~~
    test.rs:12:5: 12:20 error: This node does not have a stability attribute
    test.rs:12     pub fn baz() {}
                   ^~~~~~~~~~~~~~~
    error: aborting due to 2 previous errors

We were recording stability attributes applied to fields in the
compiler, and even annotating it in the libs, but the compiler didn't
actually do the checks to give errors/warnings in user crates.

Avoid `cat_expr Erred` notes when already in error state.

Also, to ensure we do not let the dropck get skipped, ICE if `cat_expr` errors when *not* in error state.

This is not known to be a breaking change (i.e. I do not know of a current case that causes the new ICE to be exercised).

Fix #22265

 Turn `unsafe_no_drop_flag` back into a gated-feature.

Fix #22173

 Currently we have a `set_mode` mutator, so this just adds the pairing of a
`mode` accessor to read the value.

Closes #22738

 If the filename for a path is `None` then we know that the creation of the
parent directory created the whole path so there's no need to retry the call to
`create_dir`.

Closes #22737

 Specifically, the following actions were takend:

* The `copy_memory` and `copy_nonoverlapping_memory` functions
  to drop the `_memory` suffix (as it's implied by the functionality). Both
  functions are now marked as `#[stable]`.
* The `set_memory` function was renamed to `write_bytes` and is now stable.
* The `zero_memory` function is now deprecated in favor of `write_bytes`
  directly.
* The `Unique` pointer type is now behind its own feature gate called `unique`
  to facilitate future stabilization.

[breaking-change]

 This commit moves `std::env` away from the `std::old_io` error type as well as
the `std::old_path` module. Methods returning an error now return `io::Error`
and methods consuming or returning paths use `std::path` instead of
`std::old_path`. This commit does not yet mark these APIs as `#[stable]`.

This commit also migrates `std::old_io::TempDir` to `std::fs::TempDir` with
essentially the exact same API. This type was added to interoperate with the new
path API and has its own `tempdir` feature.

Finally, this commit reverts the deprecation of `std::os` APIs returning the old
path API types. This deprecation can come back once the entire `std::old_path`
module is deprecated.

[breaking-change]

 This commit removes many unnecessary `unsafe impl` blocks as well as pushing the
needed implementations to the lowest level possible. I noticed that the bounds
for `RwLock` are a little off when reviewing #22574 and wanted to ensure that we
had our story straight on these implementations.

 r? @Gankro

 The recent commit on liblibc for nacl break the compilation for OpenBSD (and Bitrig too, I think).

The problem is `ino_t` come from another block too now. This patch remove the extra declaration.

```
.../src/liblibc/lib.rs:98:9: 98:37 error: a type named `ino_t` has already been imported in this module [E0251]
.../src/liblibc/lib.rs:98 pub use types::os::arch::posix01::*;
                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
error: aborting due to previous error
```

@dhuseby do you have this problem too ? and if yes, does this patch correct it ?

 Two changes:

1. Make traits with assoc types invariant w/r/t their inputs.
2. Fully normalize parameter environments, including any region variables (which were being overlooked).

The former supports the latter, but also just seems like a reasonably good idea.

Fixes #21750

cc @edwardw
r? @pnkfelix

 According to #22650 and bb0bbf63 the
link changed.
I think this should fix the link on http://doc.rust-lang.org/#faqs