On Windows, the gcc crate would send /Wall to msvc, which would cause
builds to get flooded with warnings, exploding compile times from one
hour to more than 72! The gcc crate version 0.3.54 changes this behavior
to send /W4 instead, which greatly cuts down on cl.exe flooding the
command prompt window with warnings.

In rust-lang#42436 the behavior for spawning processes on Windows was tweaked slightly to
fix various bugs, but this caused rust-lang#42791 as a regression, namely that to spawn
batch scripts they need to be manually spawned with `cmd /c` instead now. This
updates the compiler to handle this case explicitly for Emscripten.

Closes rust-lang#42791

cc rust-lang#44270

Most of the other rust-lang buckets are in us-west-1 and I think the original
bucket was just accidentally created in the us-east-1 region. Let's consolidate
by moving it to the same location as the rest of our buckets.

This commit alters the `query` function in the dep graph module to preallocate
memory using `with_capacity` instead of relying on automatic growth. Discovered
in rust-lang#44576 it was found that for the syntex_syntax clean incremental benchmark
the peak memory usage was found when the dep graph was being saved, particularly
the `DepGraphQuery` data structure itself. PRs like rust-lang#44142 which add more
queries end up just making this much larger!

I didn't see an immediately obvious way to reduce the size of the
`DepGraphQuery` object, but it turns out that `with_capacity` helps quite a bit!
Locally 831 MB was used [before] this commit, and 770 MB is in use at the peak
of the compiler [after] this commit. That's a nice 7.5% improvement! This won't
quite make up for the losses in rust-lang#44142 but I figured it's a good start.

[before]: https://gist.github.com/alexcrichton/2d2b9c7a65503761925c5a0bcfeb0d1e
[before]: https://gist.github.com/alexcrichton/6da51f2a6184bfb81694cc44f06deb5b

…crichton

Attempt to fix the component manifest problem for rls-preview

cc rust-lang#44270

See rust-lang#44270

…uietMisdreavus

Codeblock color

<img width="1440" alt="screen shot 2017-09-07 at 21 53 58" src="https://user-images.githubusercontent.com/3050060/30183045-4319108e-9419-11e7-98da-da54952cab37.png">

This screenshot has been generated from:

```rust
/// foo
///
/// ```compile_fail
/// foo();
/// ```
///
/// ```ignore
/// goo();
/// ```
///
/// ```
/// let x = 0;
/// ```
pub fn bar() -> usize { 2 }
```

r? @QuietMisdreavus
cc @rust-lang/docs

…chton

bump gcc for bootstrap

On Windows, the gcc crate would send /Wall to msvc, which would cause
builds to get flooded with warnings, exploding compile times from one
hour to more than 72! The gcc crate version 0.3.54 changes this behavior
to send /W4 instead, which greatly cuts down on cl.exe flooding the
command prompt window with warnings.

…, r=nikomatsakis

rustc: Spawn `cmd /c emcc.bat` explicitly

In rust-lang#42436 the behavior for spawning processes on Windows was tweaked slightly to
fix various bugs, but this caused rust-lang#42791 as a regression, namely that to spawn
batch scripts they need to be manually spawned with `cmd /c` instead now. This
updates the compiler to handle this case explicitly for Emscripten.

Closes rust-lang#42791

bring TyCtxt into scope

got comments both from @eddyb and @nikomatsakis (via rust-lang#44505) that we should always put `TyCtxt` in scope

should I just go and import it at other places in the codebase or we just keep doing small improvements?

…aidanhs

travis: Move sccache to the us-west-1 region

Most of the other rust-lang buckets are in us-west-1 and I think the original
bucket was just accidentally created in the us-east-1 region. Let's consolidate
by moving it to the same location as the rest of our buckets.

…elwoerister

rustc: Preallocate when building the dep graph

This commit alters the `query` function in the dep graph module to preallocate
memory using `with_capacity` instead of relying on automatic growth. Discovered
in rust-lang#44576 it was found that for the syntex_syntax clean incremental benchmark
the peak memory usage was found when the dep graph was being saved, particularly
the `DepGraphQuery` data structure itself. PRs like rust-lang#44142 which add more
queries end up just making this much larger!

I didn't see an immediately obvious way to reduce the size of the
`DepGraphQuery` object, but it turns out that `with_capacity` helps quite a bit!
Locally 831 MB was used [before] this commit, and 770 MB is in use at the peak
of the compiler [after] this commit. That's a nice 7.5% improvement! This won't
quite make up for the losses in rust-lang#44142 but I figured it's a good start.

[before]: https://gist.github.com/alexcrichton/2d2b9c7a65503761925c5a0bcfeb0d1e
[before]: https://gist.github.com/alexcrichton/6da51f2a6184bfb81694cc44f06deb5b

Require +thumb-mode to generate thumb2 code for Android/armv7-a

I am investigating rust's code generation into Gecko by https://bugzilla.mozilla.org/show_bug.cgi?id=1399337.

armv7-linux-androideabi target uses `+v7,+thumb2,+vfp3,+d16,-neon` as target-feature.  But `+thumb2` only doesn't generate thumb2 code.  To generate thumb2 code, it requires `+thumb-mode`.  So we should add it for armv7-linux-androideabi.

r? @alexcrichton

…xcrichton

stabilized ord_max_min (fixes rust-lang#25663)