rustc: improve -Z trans-stats to report per-fn LLVM instruction counts and translation timing
libsyntax: fix infinite loop when recursively including modules

Fixes #7276
Move `extra::net_*` to `extra::net::*` properly.

Where * = tcp, ip, url.

Formerly, extra::net::* were aliases of extra::net_*, but were the
recommended path to use. Thus, the documentation talked of the `net_*`
modules while everything else was written expecting `net::*`.

This moves the actual modules so that `extra::net::*` is the actual
location of the modules.

This will naturally break any code which used `extra::net_*` directly.
They should be altered to use `extra::net::*` (which has been the
documented way of doing things for some time).

This ensures that there is one, and only one, obvious way of doing
things.
Remove superfluous super::super::
vec: Add .pop_opt() -> Option<T>

Add a function to safely retrieve the last element of a ~[T], as
Option<T>. Implement pop() using pop_opt(); it benches the same as the
old implementation when tested with optimization level 2.
vec: Add .shift_opt() -> Option<T>

Add a function to safely retrieve the first element of a ~[T], as
Option<T>. Implement shift() using shift_opt().

Add tests for both .shift() and .shift_opt()
remove extra::rope

It's broken/unmaintained and needs to be rewritten to avoid managed
pointers and needless copies. A full rewrite is necessary and the API
will need to be redone so it's not worth keeping this around.

Closes #2236, #2744
auto merge of #7585 : Blei/rust/fix-circular-modules, r=huonw

Fixes #7276
auto merge of #7615 : Aatch/rust/syntax-deshare, r=graydon

In an ideal world, the AST would be completely sendable, this gets us a step closer.

It removes the local heap allocations for `view_item`, `Path`, `Lifetime` `trait_ref` `OptVec<TyParamBounds>` and `Ty`. There are also a few other smaller changes I made as things went along.
Implement scopes independent of LLVM basic blocks

Currently, scopes are tied to LLVM basic blocks. For each scope, there
are two new basic blocks, which means two extra jumps in the unoptimized
IR. These blocks aren't actually required, but only used to act as the
boundary for cleanups.

By keeping track of the current scope within a single basic block, we
can avoid those extra blocks and jumps, shrinking the pre-optimization
IR quite considerably. For example, the IR for trans_intrinsic goes
from ~22k lines to ~16k lines, almost 30% less.

The impact on the build times of optimized builds is rather small (about
1%), but unoptimized builds are about 11% faster. The testsuite for
unoptimized builds runs between 15% (CPU time) and 7.5% (wallclock time on
my i7) faster.

Also, in some situations this helps LLVM to generate better code by
inlining functions that it previously considered to be too large.
Likely because of the pointless blocks/jumps that were still present at
the time the inlining pass runs.

Refs #7462
auto merge of #7594 : chris-morgan/rust/proper-net-module-structure, r=huonw

Where * = tcp, ip, url.

Formerly, extra::net::* were aliases of extra::net_*, but were the
recommended path to use. Thus, the documentation talked of the `net_*`
modules while everything else was written expecting `net::*`.

This moves the actual modules so that `extra::net::*` is the actual
location of the modules.

This will naturally break any code which used `extra::net_*` directly.
They should be altered to use `extra::net::*` (which has been the
documented way of doing things for some time).

This ensures that there is one, and only one, obvious way of doing
things.
auto merge of #7602 : blake2-ppc/rust/vec-pop-opt, r=cmr

Implement methods `.pop_opt() -> Option<T>` and `.shift_opt() -> Option<T>` to allow retrieval of front/back of a vec in one operation without fail. .pop() and .shift() are changed to reuse the former two methods.

Follows the naming of the previous method .head_opt()
auto merge of #7636 : dotdash/rust/scope_cleanup, r=graydon

Currently, scopes are tied to LLVM basic blocks. For each scope, there
are two new basic blocks, which means two extra jumps in the unoptimized
IR. These blocks aren't actually required, but only used to act as the
boundary for cleanups.

By keeping track of the current scope within a single basic block, we
can avoid those extra blocks and jumps, shrinking the pre-optimization
IR quite considerably. For example, the IR for trans_intrinsic goes
from ~22k lines to ~16k lines, almost 30% less.

The impact on the build times of optimized builds is rather small (about
1%), but unoptimized builds are about 11% faster. The testsuite for
unoptimized builds runs between 15% (CPU time) and 7.5% (wallclock time on
my i7) faster.

Also, in some situations this helps LLVM to generate better code by
inlining functions that it previously considered to be too large.
Likely because of the pointless blocks/jumps that were still present at
the time the inlining pass runs.

Refs #7462
auto merge of #7456 : graydon/rust/better-trans-stats, r=cmr

This way when you compile with -Z trans-stats you'll get a per-function cost breakdown, sorted with the most expensive functions first. Should help highlight pathological code.
auto merge of #7629 : thestinger/rust/rope, r=graydon

It's broken/unmaintained and needs to be rewritten to avoid managed
pointers and needless copies. A full rewrite is necessary and the API
will need to be redone so it's not worth keeping this around (#7628).

Closes #2236, #2744
Fix accidental enum bloat in the AST