This commit adds a crate-level dashboard summarizing the stability
levels of all items for all submodules of the crate.

The information is also written as a json file, intended for consumption
by pages like http://huonw.github.io/isrustfastyet/

Closes #13541

Closes #15544

[breaking-change]

This commit removes all support in the compiler for the #[crate_id] attribute
and all of its derivative infrastructure. A list of the functionality removed is:

* The #[crate_id] attribute no longer exists
* There is no longer the concept of a version of a crate
* Version numbers are no longer appended to symbol names
* The --crate-id command line option has been removed

To migrate forward, rename #[crate_id] to #[crate_name] and only the name of the
crate itself should be mentioned. The version/path of the old crate id should be
removed.

For a transitionary state, the #[crate_id] attribute is still accepted if
the #[crate_name] is not present, but it is warned about if it is the only
identifier present.

RFC: 0035-remove-crate-id
[breaking-change]

Updated documentation to reflect md->html.
Modularized external file loading.

This commit removes superfluous to_string calls from various places

This obsoletes the old `to_err_msg` method. Replace

    println!("Error: {}", failure.to_err_msg())

    let string = failure.to_err_msg();

with

    println!("Error: {}", failure)

    let string = failure.to_str();

[breaking-change]

This commit is the final step in the libstd facade, #13851. The purpose of this
commit is to move libsync underneath the standard library, behind the facade.
This will allow core primitives like channels, queues, and atomics to all live
in the same location.

There were a few notable changes and a few breaking changes as part of this
movement:

* The `Vec` and `String` types are reexported at the top level of libcollections
* The `unreachable!()` macro was copied to libcore
* The `std::rt::thread` module was moved to librustrt, but it is still
  reexported at the same location.
* The `std::comm` module was moved to libsync
* The `sync::comm` module was moved under `sync::comm`, and renamed to `duplex`.
  It is now a private module with types/functions being reexported under
  `sync::comm`. This is a breaking change for any existing users of duplex
  streams.
* All concurrent queues/deques were moved directly under libsync. They are also
  all marked with #![experimental] for now if they are public.
* The `task_pool` and `future` modules no longer live in libsync, but rather
  live under `std::sync`. They will forever live at this location, but they may
  move to libsync if the `std::task` module moves as well.

[breaking-change]

Do this to avoid warnings on post-stage0 builds.

This grows a new option inside of rustdoc to add the ability to submit examples
to an external website. If the `--markdown-playground-url` command line option
or crate doc attribute `html_playground_url` is present, then examples will have
a button on hover to submit the code to the playground specified.

This commit enables submission of example code to play.rust-lang.org. The code
submitted is that which is tested by rustdoc, not necessarily the exact code
shown in the example.

Closes #14654

This was only ever a transitionary macro.

This commit moves reflection (as well as the {:?} format modifier) to a new
libdebug crate, all of which is marked experimental.

This is a breaking change because it now requires the debug crate to be
explicitly linked if the :? format qualifier is used. This means that any code
using this feature will have to add `extern crate debug;` to the top of the
crate. Any code relying on reflection will also need to do this.

Closes #12019

[breaking-change]

[breaking-change]

[breaking-change]

See #13983 and #14000.

Fix was originally authored by alexcrichton and then rebased a couple
times by pnkfelix, most recently atop PR 13954.

----

Regarding the change to librustdoc/lib.rs, to do `map_err` before
unwrapping a `TqskResult`: I do not understand how master is passing
without this change or something like it, since `Box<Any:Send>` does
not implement `Show`.  (Is this something that is only a problem for
the snapshot stage0 compiler?)  Still, the change I have put in here
(which was added as part of a rebase after alex's review) seems
harmless to me to apply to rustdoc at all stages, since a call to
`unwrap` is just going to `fail!` on the err case anyway.

Had to make `struct Tm` in `libtime` not serializable for now.

Instead of just blindly printing arg[0], use a constant string.
Partial fix for #13582

The goal of this refactoring is to make the rustc driver code easier to understand and use. Since this is as close to an API as we have, I think it is important that it is nice. On getting stuck in, I found that there wasn't as much to change as I'd hoped to make the stage... fns easier to use by tools.

This patch only moves code around - mostly just moving code to different files, but a few extracted method refactorings too. To summarise the changes: I added driver::config which handles everything about configuring the compiler. driver::session now just defines and builds session objects. I moved driver code from librustc/lib.rs to librustc/driver/mod.rs so all the code is one place. I extracted methods to make emulating the compiler without being the compiler a little easier. Within the driver directory, I moved code around to more logically fit in the modules.

os::args() no longer auto-borrows to &[~str].

This commit brings the local_data api up to modern rust standards with a few key
improvements:

* The `pop` and `set` methods have been combined into one method, `replace`

* The `get_mut` method has been removed. All interior mutability should be done
  through `RefCell`.

* All functionality is now exposed as a method on the keys themselves. Instead
  of importing std::local_data, you now use "key.replace()" and "key.get()".

* All closures have been removed in favor of RAII functionality. This means that
  get() and get_mut() no long require closures, but rather return
  Option<SmartPointer> where the smart pointer takes care of relinquishing the
  borrow and also implements the necessary Deref traits

* The modify() function was removed to cut the local_data interface down to its
  bare essentials (similarly to how RefCell removed set/get).

[breaking-change]

Deprecate the rev_iter pattern in all places where a DoubleEndedIterator is provided (everywhere but treemap)

This commit deprecates rev_iter, mut_rev_iter, move_rev_iter everywhere (except treemap) and also
deprecates related functions like rsplit, rev_components, and rev_str_components. In every case,
these functions can be replaced with the non-reversed form followed by a call to .rev(). To make this
more concrete, a translation table for all functional changes necessary follows:

* container.rev_iter() -> container.iter().rev()
* container.mut_rev_iter() -> container.mut_iter().rev()
* container.move_rev_iter() -> container.move_iter().rev()
* sliceorstr.rsplit(sep) -> sliceorstr.split(sep).rev()
* path.rev_components() -> path.components().rev()
* path.rev_str_components() -> path.str_components().rev()

In terms of the type system, this change also deprecates any specialized reversed iterator types (except
in treemap), opting instead to use Rev directly if any type annotations are needed. However, since
methods directly returning reversed iterators are now discouraged, the need for such annotations should
be small. However, in those cases, the general pattern for conversion is to take whatever follows Rev in
the original reversed name and surround it with Rev<>:

* RevComponents<'a> -> Rev<Components<'a>>
* RevStrComponents<'a> -> Rev<StrComponents<'a>>
* RevItems<'a, T> -> Rev<Items<'a, T>>
* etc.

The reasoning behind this change is that it makes the standard API much simpler without reducing readability,
performance, or power. The presence of functions such as rev_iter adds more boilerplate code to libraries
(all of which simply call .iter().rev()), clutters up the documentation, and only helps code by saving two
characters. Additionally, the numerous type synonyms that were used to make the type signatures look nice
like RevItems add even more boilerplate and clutter up the docs even more. With this change, all that cruft
goes away.

[breaking-change]

it should be changed when the module gets updated, so it helps to
have the `SCHEMA_VERSION` with the definitions themselves.

Has negligible improvements with gzip, but saves about 7% without it.
This also has an effect of changing the tie-breaking order of item types.

This also changes some of the download links in the documentation
to 'nightly'.