vim: Tweak how comment nesting works

Don't try to match line comments inside of a comment block. That makes
no sense and can highlight differently for people who override their
highlights.

Similarly, don't match a doc-comment inside of a comment block. It
shouldn't be highlighted differently unless it's actually a doc-comment
(and nested comments are obviously not doc comments).

Fixes #12307.
Mark top level module as a crate in rustdoc, closes #12507
std: Add cfg(test) to UnsafeArc assertions

This is a ubiquitous type in concurrent code, and the assertions are causing
significant code bloat for simple operations such as reading the pointer
(injecting a failure point, etc).

I am testing executable sizes with no I/O implementations (everything stubbed
out to return nothing), and this took the size of a libnative executable from
328K to 207K (37% reduction in size), so I think that this is one assertion
that's well worth configuring off for now.
std: Improve some I/O documentation

This lowers the #[allow(missing_doc)] directive into some of the lower modules
which are less mature. Most I/O modules now require comprehensive documentation.
syntax: Refactor diagnostics to focus on Writers

This commit alters the diagnostic emission machinery to be focused around a
Writer for emitting errors. This allows it to not hard-code emission of errors
to stderr (useful for other applications).
auto merge of #12607 : alexcrichton/rust/io++, r=brson

This lowers the #[allow(missing_doc)] directive into some of the lower modules
which are less mature. Most I/O modules now require comprehensive documentation.
std: Remove lots of allocations from log settings

Most of these are unnecessary because we're only looking at static strings. This
also moves to Vec in a few places instead of ~[T].

This didn't end up getting much of a code size win (update_log_settings is the
third largest function in the executables I'm looking at), but this seems like a
generally nice improvement regardless.
std: Avoid using "{:?}" in format strings

This removes all usage of Poly in format strings from libstd. This doesn't
prevent more future strings from coming in, but it at least removes the ones for
now.
std: Flag run_fmt() as #[inline(always)]

This function is a tiny wrapper that LLVM doesn't want to inline, and it ends up
causing more bloat than necessary. The bloat is pretty small, but it's a win of
at least 7k for small executables, and I imagine that the number goes up as
there are more calls to fail!().
auto merge of #12616 : alexcrichton/rust/size, r=huonw

I've been playing around with code size when linking to libstd recently, and these were some findings I found that really helped code size. I started out by eliminating all I/O implementations from libnative and instead just return an unimplemented error.

In doing so, a `fn main() {}` executable was ~378K before this patch, and about 170K after the patch. These size wins are all pretty minor, but they all seemed pretty reasonable to me. With native I/O not stubbed out, this takes the size of an LTO executable from 675K to 400K.
auto merge of #12632 : fhahn/rust/issue-12507-rustdoc-std-module, r=alexcrichton

This PR for #12507 marks the top level `Module` in rustdoc as a crate and does render the header accordingly.
librustc: Pass the node id so we don't fail on destructing struct variants. Fixes #11577.
rustdoc: Capture all output from rustc by default

This helps prevent interleaving of error messages when running rustdoc tests.
This has an interesting bit of shuffling with I/O handles, but other than that
this is just using the APIs laid out in the previous commit.

Closes #12623
librustc: Don't ICE when operator traits are not implemented properly. Fixes #11450
Cleaned up trans_fail functions, per eddyb request.
std: Change assert_eq!() to use {} instead of {:?}

Formatting via reflection has been a little questionable for some time now, and
it's a little unfortunate that one of the standard macros will silently use
reflection when you weren't expecting it. This adds small bits of code bloat to
libraries, as well as not always being necessary. In light of this information,
this commit switches assert_eq!() to using {} in the error message instead of
{:?}.

In updating existing code, there were a few error cases that I encountered:

* It's impossible to define Show for [T, ..N]. I think DST will alleviate this
  because we can define Show for [T].
* A few types here and there just needed a #[deriving(Show)]
* Type parameters needed a Show bound, I often moved this to `assert!(a == b)`
* `Path` doesn't implement `Show`, so assert_eq!() cannot be used on two paths.
  I don't think this is much of a regression though because {:?} on paths looks
  awful (it's a byte array).

Concretely speaking, this shaved 10K off a 656K binary. Not a lot, but sometime
significant for smaller binaries.
auto merge of #12626 : alexcrichton/rust/assert-eq, r=thestinger

Formatting via reflection has been a little questionable for some time now, and
it's a little unfortunate that one of the standard macros will silently use
reflection when you weren't expecting it. This adds small bits of code bloat to
libraries, as well as not always being necessary. In light of this information,
this commit switches assert_eq!() to using {} in the error message instead of
{:?}.

In updating existing code, there were a few error cases that I encountered:

* It's impossible to define Show for [T, ..N]. I think DST will alleviate this
  because we can define Show for [T].
* A few types here and there just needed a #[deriving(Show)]
* Type parameters needed a Show bound, I often moved this to `assert!(a == b)`
* `Path` doesn't implement `Show`, so assert_eq!() cannot be used on two paths.
  I don't think this is much of a regression though because {:?} on paths looks
  awful (it's a byte array).

Concretely speaking, this shaved 10K off a 656K binary. Not a lot, but sometime
significant for smaller binaries.
auto merge of #12627 : alexcrichton/rust/issue-12623, r=brson

This helps prevent the unfortunate interleavings found in #12623.
auto merge of #12638 : luqmana/rust/op-no-ref, r=alexcrichton

From my comment on #11450:

The reason for the ICE is because for operators `rustc` does a little bit of magic. Notice that while you implement the `Mul` trait for some type `&T` (i.e a reference to some T), you can simply do `Vec2 {..} * 2.0f32`. That is, `2.0f32` is `f32` and not `&f32`. This works because `rustc` will automatically take a reference. So what's happening is that with `foo * T`, the compiler is expecting the `mul` method to take some `&U` and then it can compare to make sure `T == U` (or more specifically that `T` coerces to `U`). But in this case, the argument of the `mul` method is not a reference and hence the "no ref" error.

I don't think we should ICE in this case since we do catch the mismatched trait/impl method and hence provide a better error message that way.

Fixes #11450
auto merge of #12639 : luqmana/rust/struct-variant-pat, r=pcwalton

We weren't passing the node id for the enum and hence it couldn't retrieve the field types for the struct variant we were trying to destructure.

Fixes #11577.