Be more clear about what this lambda expression does
Give more explanation when introducing closures
Demonstrate accessing external variable in first example
Some more closure changes
use option_env! instead of env!
Pre-step towards issue #12624 and others: Introduce ExprUseVisitor, remove the
moves computation. ExprUseVisitor is a visitor that walks the AST for a
function and calls a delegate to inform it where borrows, copies, and moves
occur.

In this patch, I rewrite the gather_loans visitor to use ExprUseVisitor, but in
future patches, I think we could rewrite regionck, check_loans, and possibly
other passes to use it as well. This would refactor the repeated code between
those places that tries to determine where copies/moves/etc occur.
Convert delegate to use an object type and remove FIXME from closed issue
add min_pos_value constant for floats

Follow-up on issue #13297 and PR #13710.  Instead of following the (confusing) C/C++ approach
of using `MIN_VALUE` for the smallest *positive* number, we introduce `MIN_POS_VALUE` (and
in the Float trait, `min_pos_value`) to represent this number.

This patch also removes a few remaining redundantly-defined constants that were missed last
time around.
Add a regex crate to the Rust distribution.

Also adds a regex_macros crate, which provides natively compiled
regular expressions with a syntax extension.

Closes #3591.

RFC: 0007-regexps
mk: Copy fewer libraries into the host artifacts
Cleaned up os::consts. The module only exposes constants for the target OS and arch.

Constants for other OS's and arch's must be defined manually.
[breaking-change]
auto merge of #13697 : pongad/rust/consts, r=alexcrichton

I decided to put architecture constants in another mod. They are not used, so a part of me is thinking of just getting rid of them altogether. The rest should be similar to what @brson wants.
Fixes #13536
Ignore regex tests (regular, cfail and benchmark) on Windows (for now).
auto merge of #13700 : BurntSushi/rust/regexp, r=alexcrichton

Implements [RFC 7](https://github.com/rust-lang/rfcs/blob/master/active/0007-regexps.md) and will hopefully resolve #3591. The crate is marked as experimental. It includes a syntax extension for compiling regexps to native Rust code.

Embeds and passes the `basic`, `nullsubexpr` and `repetition` tests from [Glenn Fowler's (slightly modified by Russ Cox for leftmost-first semantics) testregex test suite](http://www2.research.att.com/~astopen/testregex/testregex.html). I've also hand written a plethora of other tests that exercise Unicode support, the parser, public API, etc. Also includes a `regex-dna` benchmark for the shootout.

I know the addition looks huge at first, but consider these things:

1. More than half the number of lines is dedicated to Unicode character classes.
2. Of the ~4,500 lines remaining, 1,225 of them are comments.
3. Another ~800 are tests.
4. That leaves 2500 lines for the meat. The parser is ~850 of them. The public API, compiler, dynamic VM and code generator (for `regexp!`) make up the rest.
rustdoc: fixes
doc: slight design refresh
doc,rustdoc: store webfonts locally

- Avoids cross-domain requests restrictions
- Better availability of content
- No HTML queries needed for an offline build
test: Enable extern-fn-reachable test

It didn't work because it tried to call itself but symbols are not
exported as default in executables.

Note that `fun5` is not internal anymore since it is in library.
rustdoc: bring it inline
test: Remove/update some old ignored tests