Fixes Issue #7764

Running `make check` I do get a failure:

    test rt::io::extensions::test::push_bytes ... ok
    rustest rt::comm::test::oneshot_single_thread_send_port_close ... t: task failed at 'Unhandled condition:
     read_error: {kind: OtherIoError, desc: "Placeholder error. You shouldn\'t be seeing this", detail: None}',
     /Users/shout/Projects/rust/src/libstd/condition.rs:50
    /bin/sh: line 1: 35056 Abort trap: 6           x86_64-apple-darwin/stage2/test/stdtest-x86_64-apple-darwin --logfile
     tmp/check-stage2-T-x86_64-apple-darwin-H-x86_64-apple-darwin-std.log
    make: *** [tmp/check-stage2-T-x86_64-apple-darwin-H-x86_64-apple-darwin-std.ok] Error 134

Allowing them in type signatures is a significant amount of extra work, unfortunately. This also doesn't apply to static values, which takes a different code path.

Changes int/uint range_rev to iterate over range `(hi,lo]` instead of `[hi,lo)`.

Fix #5270.

Also:
* Adds unit tests for int/uint range functions
* Updates the uses of `range_rev` to account for the new semantics.  (Note that pretty much all of the updates there were strict improvements to the code in question; yay!)
* Exposes new function, `range_step_inclusive`, which does the range `[hi,lo]`, (at least when `hi-lo` is a multiple of the `step` parameter).
* Special-cases when `|step| == 1` removing unnecessary bounds-check.  (I did not check whether LLVM was already performing this optimization; I figure it would be a net win to not leave that analysis to the compiler.  If reviewer objects, I can easily remove that from the refactored code.)

(This pull request is a rebased version of PR #7524, which went stale due to recent unrelated changes to num libraries.)

r? anyone

Fix #7821.

As per @pcwalton's request, `debug!(..)` is only activated when the `debug` cfg is set; that is, for `RUST_LOG=some_module=4 ./some_program` to work, it needs to be compiled with `rustc --cfg debug some_program.rs`. (Although, there is the sneaky `__debug!(..)` macro that is always active, if you *really* need it.)

It functions by making `debug!` expand to `if false { __debug!(..) }` (expanding to an `if` like this is required to make sure `debug!` statements are typechecked and to avoid unused variable warnings), and adjusting trans to skip the pointless branches in `if true ...` and `if false ...`.

The conditional expansion change also required moving the inject-std-macros step into a new pass, and makes it actually insert them at the top of the crate; this means that the cfg stripping traverses over the macros and so filters out the unused ones.

This appears to takes an unoptimised build of `librustc` from 65s to 59s; and the full bootstrap from 18m41s to 18m26s on my computer (with general background use).

`./configure --enable-debug` will enable `debug!` statements in the bootstrap build.

That is, the `b` branch in `if true { a } else { b }` will not be
trans'd, and that expression will be exactly the same as `a`. This
means that, for example, macros conditionally expanding to `if false
{ .. }` (like debug!) will not waste time in LLVM (or trans).

An alloca in an unreachable block would shortcircuit with Undef, but with type
`Type`, rather than type `*Type` (i.e. a plain value, not a pointer) but it is
expected to return a pointer into the stack, leading to confusion and LLVM
asserts later.

Similarly, attaching the range metadata to a Load in an unreachable block
makes LLVM unhappy, since the Load returns Undef.

Fixes #7344.

The entire testsuite is converted to using info! rather than debug!
because some depend on the code within the debug! being trans'd.

The Ord impl of Version refered to the algorithm in release candidate versions of semver. [Semantic Versioning 2.0.0](http://semver.org/spec/v2.0.0.html) says, "Build metadata SHOULD be ignored when determining version precedence."

Note that Version's `le` is not "less than or equal to" now, since `lt` ignores build metadata. I think the new ordering algorithm satisfies strict weak ordering which C++ STL requires, instead of strict total ordering.

BTW, is `a || b || ... || x`-style code better or idiomatic in Rust than `if a { return true; } if b { return true; } ... if x { return true; } return false;`-style one?

Fix #7821.

Note that Version's `le` is not "less than or equal to" now, since `lt`
ignores build metadata. I think the new ordering algorithm satisfies
strict weak ordering which C++ STL requires, instead of strict total
ordering.

Macros can be conditionally defined because stripping occurs before macro
expansion, but, the built-in macros were only added as part of the actual
expansion process and so couldn't be stripped to have definitions conditional
on cfg flags.

debug! is defined conditionally in terms of the debug config, expanding to
nothing unless the --cfg debug flag is passed (to be precise it expands to
`if false { normal_debug!(...) }` so that they are still type checked, and
to avoid unused variable lints).

Note that the headers are still on `~[T]` when `T` is managed. This is continued from #7605, which removed all the code relying on the headers and removed them from `~T` for non-managed `T`.

Implement set difference, sym. difference, intersection and union using Iterators.

The set methods are left since they are part of the Set trait. A grep over the tree indicates that the four hashset operations have no users at all.

Also remove HashMap::mutate_values since it is unused, replaced by .mut_iter(), and not part of a trait.

Implement the difference, union, etc iterators with the help of a custom
iterator combinator with explicit closure environment. Reported issue #7814
to be able to use the std::iterator filter combinator.

This partially addresses #7719.

r? @graydon rustpkg can now build code from a local git repository. In the
case where the local repo is in a directory not in the RUST_PATH,
it checks out the repository into a directory in the first workspace
in the RUST_PATH.

The tests no longer try to connect to github.com, which should
solve some of the sporadic failures we've been seeing.

rustpkg can now build code from a local git repository. In the
case where the local repo is in a directory not in the RUST_PATH,
it checks out the repository into a directory in the first workspace
in the RUST_PATH.

The tests no longer try to connect to github.com, which should
solve some of the sporadic failures we've been seeing.

Let Eq::ne be implemented to the inverse of eq by default.

This closes #6247 by simply ensuring librustllvm.so gets installed to the target lib directory in addition to the host lib directory.

This should be pretty self-explanatory. The most important component is region/lifetime annotation highlighting, as previously they were interpreted as character literals and would ruin the rest of the line. The attribute regex is fairly crude, but it gets the job done and there's not much within attributes that would benefit from individual highlighting, so fancier handling didn't seem worth the trouble.

The ident regex was copied from the vim highlighter.

Minor tweak, but I was confused when first digging into json.rs docs.

I think it's clearer to say the module provides parsing and serialization.

Teach `extra::term` to support more terminal attributes than just color.

Fix the compiler diagnostic messages to print in bold instead of bright white. This matches Clang's output.

Cache the term::Terminal instead of re-parsing for every diagnostic (fixes #6827).

Stuff the term::Terminal into TLS to avoid re-parsing for every single
message we want to color.

Fixes #6827.

Clang actually highlights using bold, not using bright white. Match
clang on this so our diagnostics are still readable on terminals with a
white background.

Also add .supports_attr() to test for attribute support without writing
anything to output.

Update .reset() to use sgr0 instead of op.