This avoids duplicate errors for things like invalid fragment specifiers, or
parsing errors for ambiguous macros. Fixes #29231.

Remove hir::Ident

Now when name resolution is done on AST, `hir::Ident` is no longer necessary.
See https://github.com/rust-lang/rust/pull/30145 for more details.

r? @nrc

Warnings for issue #32330

This is an extension of the previous PR that issues warnings in more situations than before. It does not handle *all* cases of #32330 but I believe it issues warnings for all cases I've seen in practice.

Before merging I'd like to address:

- open a good issue explaining the problem and how to fix it (I have a [draft writeup][])
- work on the error message, which I think is not as clear as it could/should be (suggestions welcome)

r? @aturon

[draft writeup]: https://gist.github.com/nikomatsakis/631ec8b4af9a18b5d062d9d9b7d3d967

This is a step towards fixing #32330. The full fix would be a breaking
change, so we begin by issuing warnings for scenarios that will break.

We ought not to be affecting inference state when assembling candidates,
so invoke select inside of a probe.

Added a big-picture explanation for thread::park() & co.

As I said in https://www.reddit.com/r/rust/comments/4ihvv1/hey_rust_programmers_got_a_question_ask_here/d372s4i, the current explanation of the `park()` and `unpark()` is a bit unclear. It says that they're used for blocking, but then it goes on explaining the semantics in detail, leaving the bigger picture a bit unclear.

I added a short high-level explanation that explains how the functions are used. I also exposed the full paths (`thread::park()` and `thread::Thread::unpark()`), because `unpark()`, being a method, is not directly visible at the module level.

Fix invalid enum declaration

r? @steveklabnik
cc @Ms2ger

IntelliJ support, ordering, cleanup

Update i686-linux-android features to match android x86 ABI.

Based on [android's official x86 ABI info](http://developer.android.com/ndk/guides/abis.html#x86), the x86 baseline CPU can be safely updated to `pentiumpro`, with the addition of `MMX`, `SSE`, `SSE2`, `SSE3`, `SSSE3` features.

r? @alexcrichton

Replace the obligation forest with a graph

In the presence of caching, arbitrary nodes in the obligation forest can be merged, which makes it a general graph. Handle it as such, using cycle-detection algorithms in the processing.

I should do performance measurements sometime.

This was pretty much written as a proof-of-concept. Please help me write this in a less-ugly way. I should also add comments explaining what is going on.

r? @nikomatsakis

add UI testing framework

This adds a framework for capturing and tracking the precise output of rustc, which allows us to check all manner of minor details with the output. It's pretty strict right now -- the output must match almost exactly -- and hence maybe a bit too strict. But I figure we can add wildcards or whatever later. There is also a script intended to make updating the references easy, though the script could make things a *bit* easier (in particular, it'd be nice if it would find the build directory for you automatically).

One thing I was wondering about is the best way to test colors. Since windows doesn't embed those in the output stream, this test framework can't test colors on windows -- so I figure we can just write tests that are ignored on windows and which pass `--color=always` or whatever to rustc.

cc @jonathandturner
r? @alexcrichton

Do not rename invalid identifiers, they stop being invalid after renaming

Update aarch64-linux-android target to match android abi.

- Changed `target_env` to "gnu" to empty "" for all android targets because it does not matter for android.
- The PR #33048 added "max_atomic_width" for arm-android but missed recently added armv7-android. Add it there too.
- Added features `+neon,+fp-armv8` because they [must exist on `aarch64` android](http://developer.android.com/ndk/guides/cpu-features.html).
- Update libc to include https://github.com/rust-lang/libc/pull/282 so that rust's std lib works on android's aarch64 (the main issue there was incorrect structure alignment on 64-bit arm).

r? @alexcrichton

Fix fast path of float parsing on x87

The fast path of the float parser relies on the rounding to happen
exactly and directly to the correct number of bits. On x87, instead,
double rounding would occour as the FPU stack defaults to 80 bits of
precision.

This can be fixed by setting the precision of the FPU stack before
performing the int to float conversion. This can be achieved by
changing the value of the x87 control word. This is a somewhat common
operation that is in fact performed whenever a float needs to be
truncated to an integer, but it is undesirable to add its overhead for
code that does not rely on x87 for computations (i.e. on non-x86
architectures, or x86 architectures which perform FPU computations on
using SSE).

Fixes `num::dec2flt::fast_path_correct` (on x87).

rename a few occurrences of RecoverSafe in docs

The `volatile` modifier was incorrectly written outside of the `asm!`
blocks.

Remove irrelevant information (and instead provide pointer to
reference documentation), replace ASCII-art table with the
corresponding MarkDown one, and minor fixes.

diagnostics: Fix minor typo in E0038

test: explicitely check the number of spawned threads in tcp-stress

System limits may restrict the number of threads effectively spawned by this test (eg. systemd recently introduced a 512 tasks per unit maximum default).
Now this test explicitly asserts on the expected number of threads, making failures due to system limits easier to spot.
More details at https://bugs.debian.org/822325

Remove ExplicitSelf from HIR

`self` argument is already kept in the argument list and can be retrieved from there if necessary, so there's no need for the duplication.
The same changes can be applied to AST, I'll make them in the next breaking batch.
The first commit also improves parsing of method declarations and fixes https://github.com/rust-lang/rust/issues/33413.

r? @EddyB

Fix a typo in error messages in std::fs tests

Just a small correction to fix a typo in an error message in std::fs tests

Rollup of 27 pull requests

- Successful merges: #33342, #33393, #33415, #33475, #33517, #33533, #33534, #33565, #33580, #33584, #33585, #33588, #33590, #33591, #33593, #33598, #33600, #33602, #33603, #33604, #33605, #33607, #33612, #33620, #33633, #33634, #33635
- Failed merges: #33578

Update link to license

Permanent redirect (301). The link should be updated.

doc: 'tis the lang, not the reptile

doc: improve output

doc: this statement does not have an effect

rustbuild: Ignore user config.toml file.

r? @EddyB

doc: use less awkward and less confusing language

doc: line these comments up

Looks more nice, and same is done with prior examples

doc: to_string not needed since we gots coercion