rustdoc: refactor and unstyle inline section headers
doc: perform some 80-chars wrappings
rustdoc: style tweaks
Add a streaming parser to serialize::json.
Fix a code formatting issue in json.rs
Update libworkcache with libserialize's json changes
Fix test issue-4016.rs with the json API change
std: Rewrite crate docs

Also move prelude explanation to the prelude module.
rustdoc: fix a few inconsistencies
regex: remove the use of ~[] & some unnecessary ~'s.

The AST doesn't need ~s everywhere, so we can save allocations this way
& the enum isn't particularly large (~4 words) nor are regexes
long (normally), so the space saved in the `Cat` vector is unlikely to
be very much.
rustc: Enable -f{function,data}-sections

The compiler has previously been producing binaries on the order of 1.8MB for
hello world programs "fn main() {}". This is largely a result of the compilation
model used by compiling entire libraries into a single object file and because
static linking is favored by default.

When linking, linkers will pull in the entire contents of an object file if any
symbol from the object file is used. This means that if any symbol from a rust
library is used, the entire library is pulled in unconditionally, regardless of
whether the library is used or not.

Traditional C/C++ projects do not normally encounter these large executable
problems because their archives (rust's rlibs) are composed of many objects.
Because of this, linkers can eliminate entire objects from being in the final
executable. With rustc, however, the linker does not have the opportunity to
leave out entire object files.

In order to get similar benefits from dead code stripping at link time, this
commit enables the -ffunction-sections and -fdata-sections flags in LLVM, as
well as passing --gc-sections to the linker *by default*. This means that each
function and each global will be placed into its own section, allowing the
linker to GC all unused functions and data symbols.

By enabling these flags, rust is able to generate much smaller binaries default.
On linux, a hello world binary went from 1.8MB to 597K (a 67% reduction in
size). The output size of dynamic libraries remained constant, but the output
size of rlibs increased, as seen below:

    libarena         -  2.27% bigger (   292872 =>    299508)
    libcollections   -  0.64% bigger (  6765884 =>   6809076)
    libflate         -  0.83% bigger (   186516 =>    188060)
    libfourcc        - 14.71% bigger (   307290 =>    352498)
    libgetopts       -  4.42% bigger (   761468 =>    795102)
    libglob          -  2.73% bigger (   899932 =>    924542)
    libgreen         -  9.63% bigger (  1281718 =>   1405124)
    libhexfloat      - 13.88% bigger (   333738 =>    380060)
    liblibc          - 10.79% bigger (   551280 =>    610736)
    liblog           - 10.93% bigger (   218208 =>    242060)
    libnative        -  8.26% bigger (  1362096 =>   1474658)
    libnum           -  2.34% bigger (  2583400 =>   2643916)
    librand          -  1.72% bigger (  1608684 =>   1636394)
    libregex         -  6.50% bigger (  1747768 =>   1861398)
    librustc         -  4.21% bigger (151820192 => 158218924)
    librustdoc       -  8.96% bigger ( 13142604 =>  14320544)
    librustuv        -  4.13% bigger (  4366896 =>   4547304)
    libsemver        -  2.66% bigger (   396166 =>    406686)
    libserialize     -  1.91% bigger (  6878396 =>   7009822)
    libstd           -  3.59% bigger ( 39485286 =>  40902218)
    libsync          -  3.95% bigger (  1386390 =>   1441204)
    libsyntax        -  4.96% bigger ( 35757202 =>  37530798)
    libterm          - 13.99% bigger (   924580 =>   1053902)
    libtest          -  6.04% bigger (  2455720 =>   2604092)
    libtime          -  2.84% bigger (  1075708 =>   1106242)
    liburl           -  6.53% bigger (   590458 =>    629004)
    libuuid          -  4.63% bigger (   326350 =>    341466)
    libworkcache     -  8.45% bigger (  1230702 =>   1334750)

This increase in size is a result of encoding many more section names into each
object file (rlib). These increases are moderate enough that this change seems
worthwhile to me, due to the drastic improvements seen in the final artifacts.
The overall increase of the stage2 target folder (not the size of an install)
went from 337MB to 348MB (3% increase).

Additionally, linking is generally slower when executed with all these new
sections plus the --gc-sections flag. The stage0 compiler takes 1.4s to link the
`rustc` binary, where the stage1 compiler takes 1.9s to link the binary. Three
megabytes are shaved off the binary. I found this increase in link time to be
acceptable relative to the benefits of code size gained.

This commit only enables --gc-sections for *executables*, not dynamic libraries.
LLVM does all the heavy lifting when producing an object file for a dynamic
library, so there is little else for the linker to do (remember that we only
have one object file).

I conducted similar experiments by putting a *module's* functions and data
symbols into its own section (granularity moved to a module level instead of a
function/static level). The size benefits of a hello world were seen to be on
the order of 400K rather than 1.2MB. It seemed that enough benefit was gained
using ffunction-sections that this route was less desirable, despite the lesser
increases in binary rlib size.
auto merge of #13772 : brson/rust/cratedocs, r=alexcrichton

Also move prelude explanation to the prelude module.

This tries to provide a guide to what's in the standard library, organized bottom up from primitives to I/O.
auto merge of #13833 : alexcrichton/rust/ffunction-sections, r=thestinger

The compiler has previously been producing binaries on the order of 1.8MB for
hello world programs "fn main() {}". This is largely a result of the compilation
model used by compiling entire libraries into a single object file and because
static linking is favored by default.

When linking, linkers will pull in the entire contents of an object file if any
symbol from the object file is used. This means that if any symbol from a rust
library is used, the entire library is pulled in unconditionally, regardless of
whether the library is used or not.

Traditional C/C++ projects do not normally encounter these large executable
problems because their archives (rust's rlibs) are composed of many objects.
Because of this, linkers can eliminate entire objects from being in the final
executable. With rustc, however, the linker does not have the opportunity to
leave out entire object files.

In order to get similar benefits from dead code stripping at link time, this
commit enables the -ffunction-sections and -fdata-sections flags in LLVM, as
well as passing --gc-sections to the linker *by default*. This means that each
function and each global will be placed into its own section, allowing the
linker to GC all unused functions and data symbols.

By enabling these flags, rust is able to generate much smaller binaries default.
On linux, a hello world binary went from 1.8MB to 597K (a 67% reduction in
size). The output size of dynamic libraries remained constant, but the output
size of rlibs increased, as seen below:

    libarena       -  2.27% bigger
    libcollections -  0.64% bigger
    libflate       -  0.85% bigger
    libfourcc      - 14.67% bigger
    libgetopts     -  4.52% bigger
    libglob        -  2.74% bigger
    libgreen       -  9.68% bigger
    libhexfloat    - 13.68% bigger
    liblibc        - 10.79% bigger
    liblog         - 10.95% bigger
    libnative      -  8.34% bigger
    libnum         -  2.31% bigger
    librand        -  1.71% bigger
    libregex       -  6.43% bigger
    librustc       -  4.21% bigger
    librustdoc     -  8.98% bigger
    librustuv      -  4.11% bigger
    libsemver      -  2.68% bigger
    libserialize   -  1.92% bigger
    libstd         -  3.59% bigger
    libsync        -  3.96% bigger
    libsyntax      -  4.96% bigger
    libterm        - 13.96% bigger
    libtest        -  6.03% bigger
    libtime        -  2.86% bigger
    liburl         -  6.59% bigger
    libuuid        -  4.70% bigger
    libworkcache   -  8.44% bigger

This increase in size is a result of encoding many more section names into each
object file (rlib). These increases are moderate enough that this change seems
worthwhile to me, due to the drastic improvements seen in the final artifacts.
The overall increase of the stage2 target folder (not the size of an install)
went from 337MB to 348MB (3% increase).

Additionally, linking is generally slower when executed with all these new
sections plus the --gc-sections flag. The stage0 compiler takes 1.4s to link the
`rustc` binary, where the stage1 compiler takes 1.9s to link the binary. Three
megabytes are shaved off the binary. I found this increase in link time to be
acceptable relative to the benefits of code size gained.

This commit only enables --gc-sections for *executables*, not dynamic libraries.
LLVM does all the heavy lifting when producing an object file for a dynamic
library, so there is little else for the linker to do (remember that we only
have one object file).

I conducted similar experiments by putting a *module's* functions and data
symbols into its own section (granularity moved to a module level instead of a
function/static level). The size benefits of a hello world were seen to be on
the order of 400K rather than 1.2MB. It seemed that enough benefit was gained
using ffunction-sections that this route was less desirable, despite the lesser
increases in binary rlib size.
regex: General style tweaks.

For loops are nicer than manual whiles, etc.
auto merge of #13776 : adrientetar/rust/rustdoc-fix, r=brson

- Closes #13591. Relevant example: http://adrientetar.legtux.org/cached/rust-docs/struct.CChars.htm
(Had to use `!important` to override CSS selector precedence, namely matching over parent class.)
- Implement changes from #13780 feedback, namely:
  * Changed font-size from 18px to 15px
  * Reintroduced gray background for code samples
  * Tightened up the margins
- Fix point 1 and point 4 of #13804.

Samples:

- [enum.FileType](http://adrientetar.legtux.org/cached/rust-docs/enum.FileType.htm)
- [struct.CChars](http://adrientetar.legtux.org/cached/rust-docs/struct.CChars.htm)
- [std](http://adrientetar.legtux.org/cached/rust-docs/std.htm)
- [std::io](http://adrientetar.legtux.org/cached/rust-docs/io.htm).

r? @brson
Add a bitflags! macro

The `bitflags!` macro generates a `struct` that holds a set of C-style bitmask flags. It is useful for creating typesafe wrappers for C APIs.

For example:

~~~rust
#[feature(phase)];
#[phase(syntax)] extern crate collections;

bitflags!(Flags: u32 {
    FlagA       = 0x00000001,
    FlagB       = 0x00000010,
    FlagC       = 0x00000100,
    FlagABC     = FlagA.bits
                | FlagB.bits
                | FlagC.bits
})

fn main() {
    let e1 = FlagA | FlagC;
    let e2 = FlagB | FlagC;
    assert!((e1 | e2) == FlagABC);   // union
    assert!((e1 & e2) == FlagC);     // intersection
    assert!((e1 - e2) == FlagA);     // set difference
}
~~~
Document how generated bitflags can be extended with type and trait implementations
Document derived traits for bitset! macro
rustc: Add search paths to dylib load paths

When a syntax extension is loaded by the compiler, the dylib that is opened may
have other dylibs that it depends on. The dynamic linker must be able to find
these libraries on the system or else the library will fail to load.

Currently, unix gets by with the use of rpaths. This relies on the dylib not
moving around too drastically relative to its dependencies. For windows,
however, this is no rpath available, and in theory unix should work without
rpaths as well.

This modifies the compiler to add all -L search directories to the dynamic
linker's set of load paths. This is currently managed through environment
variables for each platform.

Closes #13848
auto merge of #13857 : alexcrichton/rust/add-dylib-paths, r=brson

When a syntax extension is loaded by the compiler, the dylib that is opened may
have other dylibs that it depends on. The dynamic linker must be able to find
these libraries on the system or else the library will fail to load.

Currently, unix gets by with the use of rpaths. This relies on the dylib not
moving around too drastically relative to its dependencies. For windows,
however, this is no rpath available, and in theory unix should work without
rpaths as well.

This modifies the compiler to add all -L search directories to the dynamic
linker's set of load paths. This is currently managed through environment
variables for each platform.

Closes #13848