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]

Fix small bug introduced in e38cb972: PatIdent span was incorrect
because self.last_span was being used before the ident token was
parsed.

Inadvertently changed the order in which destructors ran in certain cases with #15076.

Fixes #15438.

In my informal measurements, this brings the peak memory usage when
building librustc from 1662M down to 1502M.  Since 1662 - 1502 = 160,
this may not recover the entirety of the observed memory regression
(250M) from PR #14604.  (However, according to my local measurements,
the regression when building librustc was more like 209M, so perhaps
this will still recover the lions share of the lost memory.)

The types `Bitv` and `BitvSet` are badly out of date. This PR:
- cleans up the code (primarily, simplifies `Bitv` and implements `BitvSet` in terms of `Bitv`)
- implements several new traits for `Bitv`
- adds new functionality to `Bitv` and `BitvSet`
- replaces internal iterators with external ones
- updates documentation
- minor bug fixes

This is a significantly souped-up version of PR #15139 and is the result of the discussion there.

In my informal measurements, this brings the peak memory usage when
building librustc from 1662M down to 1502M.  Since 1662 - 1502 = 160,
this may not recover the entirety of the observed memory regression
(250M) from PR #14604.  (However, according to my local measurements,
the regression when building librustc was more like 209M, so perhaps
this will still recover the lions share of the lost memory.)

This basically meant changing the interface so that no borrowed `&Vec`
is exposed, by hiding `fn get_vec` and `fn get_mut_vec` and revising
`fn all_vecs`.

Instead, clients should use one of the other methods; `get_slice`,
`pop`, `truncate`, `replace`, `push_all`, or `is_empty_in`, which
should work for any case currently used in rustc.

This pull request adds hygiene for 3 kinds of argument bindings:
- arguments to item fns,
- arguments to `ExprFnBlock`s, and
- arguments to `ExprProc`s

It also adds a bunch of unit tests, fixes a few macro uses to be non-capturing, and has a few cleanup items.

local `make check` succeeds.

This speeds up json serialization by removing most of the allocations.

This significantly speeds up encoding json strings.

Fix small bug introduced in e38cb972: PatIdent span was incorrect
because self.last_span was being used before the ident token was
parsed.

also, introduce fn_decl_arg_bindings and expand_and_rename abstractions

This was parsed by the parser but completely ignored; not even stored in
the AST!

This breaks code that looks like:

    static X: &'static [u8] = &'static [1, 2, 3];

Change this code to the shorter:

    static X: &'static [u8] = &[1, 2, 3];

Closes #15312.

[breaking-change]

r? @nick29581

This implementation does have the minor issue of not handling things correctly when a codepoint is split across multiple writes or reads, but its better than not having unicode support at all.

Adds a Windows specific struct `WindowsTTY` in `libnative` and make `tty_open` create that struct on Windows. Adds needed functions and constants to `c_win32.rs`.

Libuv still needs to be updated before #15028 can be closed.

Adds a WindowsTTY for libnative that converts between UTF-8 and UTF-16.
Signed-off-by: NPeter Atashian <retep998@gmail.com>

It was required to get iOS compilable but since
that time a couple of changes were introduced
which cause the same bug to re-appear and broke 
build anyway. Fixing all of them doesn’t look a 
viable alternative to me as it will pollute the 
code too much.

So it should be fixed from LLVM side and I hope 
LLVM will upstream corresponding changes in a 
month.

Meanwhile, who wants to play with Rust on iOS is 
better to use a fork which uses patched LLVM:
https://github.com/vhbit/rust/tree/ios . It may 
lag behind master a bit, but it is Travis-checked 
to compile successfully.