Give compile_error macro examples

I cannot get Rust to build at all with it complaining about GCC not being a valid C compiler or something, so letting TravisCI be my tester...

Fixes #46171

Improve search style

Fixes #46494.

r? @QuietMisdreavus

Update old link

The CONTRIBUTING.md page currently links to an old wiki page in rust-lang/rust-wiki-backup. There is a more up-to-date page in-tree so I changed the link to point there so new contributors can find it more easily.

Document behavior of `ptr::swap` with overlapping regions of memory.

Fixes https://github.com/rust-lang/rust/issues/44479.

Mention the name of ? in Result's docs

Fixes #42725

or at least, this is the best we can really do. #35946 is tracking
better errors already, so that should cover the other part of it.

Fix use of rand in liballoc benches

Clarify what `-D warnings` or `-F warnings` does

They set all lints currently on the warning level to `deny` or `forbid`,
respectively.

coherence: fix is_knowable logic

A trait-ref that passes the orphan-check rules can still be implemented in a crate downstream from our crate (for example, `LocalType for LocalTrait<_>` might be matched by a `LocalType for LocalTrait<TypeFromDownstreamCrate>`), and this should be known by the `is_knowable`  logic.

Trait selection had a hackfix for this, but it's an hacky fix that does not handle all cases. This patch removes it.

fixes #43355.

r? @nikomatsakis

Needs a crater run

rustc_trans: don't write discriminants for uninhabited variants

Fixes #46519.

Patch as suggested by eddyb: https://github.com/rust-lang/rust/issues/46519#issuecomment-349443519

Update rls and rustfmt and set them testing

r? @alexcrichton

Change "Types/modules" title of search tab to be more accurate

From issue #45787. Used "In name" as per suggestion from @Seeker14491.

Fixes #46519.

Patch as suggested by eddyb:
https://github.com/rust-lang/rust/issues/46519#issuecomment-349443519

Tabs are "In Names", "In Parameters", and "In Return Types".

template month/year, version into man pages while building dist tarball

![the_man](https://user-images.githubusercontent.com/1076988/33596149-963956f4-d94f-11e7-926f-e683217765e5.png)

This is meant to resolve #25689.

r? @alexcrichton

Add armv5te-unknown-linux-gnueabi to cross builder

This is the only linux target missing in the dist builders.

Fixes #42725

or at least, this is the best we can really do. #35946 is tracking
better errors already, so that should cover the other part of it.

rustc_mir: don't move temporaries that are still used later.

This should unbreak using the MIR borrow-checker on `libcore` (assuming #46268 is merged).

Remove librustdoc dependency on log

This change should have been included in PR #46386.

Since librustdoc doesn't explicitly depend on internal crates
(such as librustc_driver) through its Cargo.toml, it ends up using the
sysroot to resolve them. By removing the dependency on 'log',
we ensure that the syroot is used to resolve `log` as well. This ensures
that only one version of log is in use, so that `env_logger::init()`
enables all uses of `log!` macros.

This is meant to resolve #25689.

Rename cross(2) builder to dist-various-{1,2}

Follows the convention of the other builders.

Fixes https://github.com/rust-lang/rust/issues/44479.

Report a targeted note for generic parameters that are missing a trait bound

Move rustc_back modules where they belong.

This change should have been included in PR #46386.

Since librustdoc doesn't explicitly depend on internal crates
(such as librustc_driver) through its Cargo.toml, it ends up using the
sysroot to resolve them. By removing the dependency on 'log',
we ensure that the syroot is used to resolve `log` as well. This ensures
that only one version of log is in use, so that `env_logger::init()`
enables all uses of `log!` macros.

incr.comp.: Incorporate the stable commandline arg hash and SVHs of upstream crates into the SVH.

So far the SVH detected changes in the HIR, which is already very sensitive, but in order for `eval_always` queries to also be sensitive to changes in upstream crates, the SVH also needs to capture changes there.

This PR fixes [rust-icci/crossbeam](https://travis-ci.org/rust-icci/crossbeam/builds/308936448), but I have not yet been able to come up with a minimal regression test.

r? @nikomatsakis

NLL: improve inference with flow results, represent regions with bitsets, and more

This PR begins with a number of edits to the NLL code and then includes a large number of smaller refactorings (these refactorings ought not to change behavior). There are a lot of commits here, but each is individually simple. The goal is to land everything up to but not including the changes to how we handle closures, which are conceptually more complex.

The NLL specific changes are as follows (in order of appearance):

**Modify the region inferencer's approach to free regions.** Previously, for each free region (lifetime parameter) `'a`, it would compute the set of other free regions that `'a` outlives (e.g., if we have `where 'a: 'b`, then this set would be `{'a, 'b}`). Then it would mark those free regions as "constants" and report an error if inference tried to extend `'a` to include any other region (e.g., `'c`) that is not in that outlives set. In this way, the value of `'a` would never grow beyond the maximum that could type check. The new approach is to allow `'a` to grow larger. Then, after the fact, we check over the value of `'a` and see what other free regions it is required to outlive, and we check that those outlives relationships are justified by the where clauses in scope etc.

**Modify constraint generation to consider maybe-init.** When we have a "drop-live" variable `x` (i.e., a variable that will be dropped but will not be otherwise used), we now consider whether `x` is "maybe initialized" at that point. If not, then we know the drop is a no-op, and we can allow its regions to be dead. Due to limitations in the fragment code, this currently only works at the level of entire variables.

**Change representation of regions to use a `BitMatrix`.** We used to use a `BTreeSet`, which was rather silly. We now use a MxN matrix of bits, where `M` is the number of variables and `N` is the number of possible elements in each set (size of the CFG + number of free regions).

The remaining commits (starting from
extract the `implied_bounds` code into a helper function ") are all "no-op" refactorings, I believe.

~~One concern I have is with the commit "with -Zverbose, print all details of closure substs"; this commit seems to include some "internal" stuff in the mir-dump files, such as internal interner numbers, that I fear may vary by platform. Annoying. I guess we will see.~~ (I removed this commit.)

As for reviewer, @arielb1 has been reviewing the PRs, and they are certainly welcome to review this one too. But I figured it'd maybe be good to have more people taking a look and being familiar with this code, so I'll "nominate" @pnkfelix .

r? @pnkfelix