Closes #16725

The privacy pass of the compiler was previously not taking into account the
privacy of foreign items, or bindings to external functions. This commit fixes
this oversight by encoding the visibility of foreign items into the metadata for
each crate.

Any code relying on this will start to fail to  compile and the bindings must be
marked with `pub` to indicate that they can be used externally.

Closes #16725
[breaking-change]

Closes #8492.

I did not find this suggestion in the [guidelines][] but it's mentioned in the [old style guide][].

[guidelines]: https://github.com/rust-lang/rust-guidelines
[old style guide]: https://github.com/rust-lang/rust/wiki/Note-style-guide/73c864a10a8e231e2a6630e5a3461f1d3022a20a

If a task is spinning in an accept loop, there is currently no method of gracefully shutting it down. This PR introduces a way to do so by cloning the acceptor and implementing a close_accept method to unblocking any pending acceptor.

As with other I/O methods like this, it is `#[experimental]` from the start and sadly carries with it a good deal of code to support it. Much of the complication is from the fact that you can now concurrently accept on the same socket.

I tried to add a good deal of tests for this change, but another set of eyes is always appreciated!

This commits takes a similar strategy to the previous commit to implement
close_accept and clone for the native win32 pipes implementation.

Closes #15595

Document the new code for how close_accept and timeouts are implemented.

This commit implements TcpAcceptor::{close, close_accept} for windows via
WSAEVENT types.

This commits implements {Tcp,Unix}Acceptor::{clone,close_accept} methods for
all of librustuv.

This implementation rewrites much of Access, AccessTimeout, and AcceptTimeout to
have type parameter for shared state that all acceptors share (a shared queue of
sockets). The incoming/outgoing channels have been removed as all timeouts and
such are now managed on the event loop rather than concurrently.

This commits implements {Tcp,Unix}Acceptor::{clone,close_accept} methods for
unix. A windows implementation is coming in a later commit.

The clone implementation is based on atomic reference counting (as with all
other clones), and the close_accept implementation is based on selecting on a
self-pipe which signals that a close has been seen.

Shows linker spew even when linking succeeds.  This is occasionally useful in order to see verbose linker output.

This lets the parser understand trailing commas in method calls, method definitions, enum variants, and type parameters.

Closes #14240.
Closes #15887.

Current version of rust fails when casting from bool, e.g.
```rust
fn main() {
    let _a = false as uint;
    let _b = true as uint;
    let _c: [bool, ..false as uint];
    let _d: [bool, ..true as uint];
    // _a and _b work, but _c and _d result in an error
    // error: expected constant expr for vector length: can't cast str to uint
}
```
This commit makes it work as expected.

Use ExactSize::len() and defer to its decisions about overly defensive
assertions. Remove the length double-check and simply put a failure
case if the Zip finds an uneven end in .next_back().

Fixing this up since I think I wrote this, and it's been known to
confuse rusties (PR #15886).

Use ExactSize::len() and defer to its decisions about overly defensive
assertions. Remove the length double-check and simply put a failure
case if the Zip finds an uneven end in .next_back().

Fixing this up since I think I wrote this, and it's been known to
confuse rusties (PR#15886).

Also:

* Remove unseeming repetition.
* By now, the reader has already heard that Rust is safe by default, so
reduce the overlong sentence, making it easier to read.

Fixes #9536 

---

From https://github.com/rust-lang/rust/issues/9536#issuecomment-45495670:

I've built rustc with the aforementioned fix, once with MergeFunc being run early (that's what the patch for clang that comes  with LLVM does), and once with MergeFunc being run late (using `-C passes=mergefunc`). Here are some time/code size measurements I made with them:

Build command: `rustc -O -o /dev/null --emit asm .../lib.rs`

CPU (user) times, best of three runs:

 Crate       | No MergeFunc | Early MergeFunc | Late MergeFunc
-------------|--------------|-----------------|---------------
 core        |    5.380s    |    5.476s       |    5.364s
 collections |    1.884s    |    1.856s       |    1.892s
 native      |    7.200s    |    7.356s       |    7.108s
 rustc       | 3m23.584s    | 3m28.120s       | 3m21.820s
 std         |   13.888s    |   13.976s       |   13.848s
 syntax      |   48.992s    |   47.752s       |   48.372s

Sizes:

Crate                                    | No MergeFunc |   Early MergeFunc   |    Late MergeFunc
-----------------------------------------|-------------:|--------------------:|-------------------:
lib                                      |  237037581   |  236005998 (-0.44%) |  234708744 (-0.98%)
libarena-063bff73-0.11.0-pre.so          |      60398   |      60393 (-0.01%) |      60394 (-0.01%)
libcollections-d412c0c4-0.11.0-pre.so    |     971566   |     971772 (+0.02%) |     971691 (+0.01%)
libdebug-1e940314-0.11.0-pre.so          |     181352   |     181514 (+0.09%) |     181363 (+0.01%)
libflate-92afea7e-0.11.0-pre.so          |     137837   |     137869 (+0.02%) |     137837 (+0.00%)
libfmt_macros-5125f3bd-0.11.0-pre.so     |     132733   |     134598 (+1.41%) |     132465 (-0.20%)
libgetopts-c94737d1-0.11.0-pre.so        |     158851   |     157427 (-0.90%) |     158272 (-0.36%)
libgraphviz-7b3cf89d-0.11.0-pre.so       |      53337   |      53178 (-0.30%) |      53337 (+0.00%)
liblog-cd053230-0.11.0-pre.so            |      85993   |      86017 (+0.03%) |      85780 (-0.25%)
libnative-1fb5e2c0-0.11.0-pre.so         |     635785   |     639352 (+0.56%) |     621184 (-2.30%)
libregex-77385931-0.11.0-pre.so          |     450538   |     450741 (+0.05%) |     449504 (-0.23%)
librustc-d252d482-0.11.0-pre.so          |   51583741   |   51227703 (-0.69%) |   50930784 (-1.27%)
librustdoc-6ecbf63e-0.11.0-pre.so        |    4557104   |    4501896 (-1.21%) |    4394409 (-3.57%)
libserialize-0352aab7-0.11.0-pre.so      |    1126096   |    1115503 (-0.94%) |    1101734 (-2.16%)
libstd-59beb4f7-0.11.0-pre.so            |    4499529   |    4488879 (-0.24%) |    4477710 (-0.48%)
libsync-305341d2-0.11.0-pre.so           |     306767   |     312211 (+1.77%) |     304086 (-0.87%)
libsyntax-555559ea-0.11.0-pre.so         |    6699751   |    6632291 (-1.01%) |    6596232 (-1.55%)
libterm-4e4945a5-0.11.0-pre.so           |     389390   |     392689 (+0.85%) |     385525 (-0.99%)
libtest-a79f950d-0.11.0-pre.so           |     740161   |     730673 (-1.28%) |     734534 (-0.76%)
libtime-4bb3739b-0.11.0-pre.so           |     131518   |     132830 (+1.00%) |     131514 (-0.00%)
rustlib                                  |  164131038   |  163594366 (-0.33%) |  162796293 (-0.81%)
x86_64-unknown-linux-gnu                 |  164119867   |  163583195 (-0.33%) |  162785122 (-0.81%)
lib                                      |  164115771   |  163579099 (-0.33%) |  162781026 (-0.81%)
liballoc-1085c790-0.11.0-pre.rlib        |    1094410   |    1094444 (+0.00%) |    1094438 (+0.00%)
libarena-063bff73-0.11.0-pre.rlib        |     312324   |     312152 (-0.06%) |     312210 (-0.04%)
libarena-063bff73-0.11.0-pre.so          |      60394   |      60394 (+0.00%) |      60394 (+0.00%)
libcollections-d412c0c4-0.11.0-pre.rlib  |    7048646   |    7049094 (+0.01%) |    7048856 (+0.00%)
libcollections-d412c0c4-0.11.0-pre.so    |     971575   |     971771 (+0.02%) |     971681 (+0.01%)
libcompiler-rt.a                         |     573802   |     573802 (+0.00%) |     573802 (+0.00%)
libcore-c5ed6fb4-0.11.0-pre.rlib         |   24204746   |   24209820 (+0.02%) |   24187602 (-0.07%)
libdebug-1e940314-0.11.0-pre.rlib        |     876616   |     878488 (+0.21%) |     876746 (+0.01%)
libdebug-1e940314-0.11.0-pre.so          |     181352   |     181509 (+0.09%) |     181353 (+0.00%)
libflate-92afea7e-0.11.0-pre.rlib        |     175062   |     175074 (+0.01%) |     175082 (+0.01%)
libflate-92afea7e-0.11.0-pre.so          |     137837   |     137869 (+0.02%) |     137837 (+0.00%)
libfmt_macros-5125f3bd-0.11.0-pre.so     |     132724   |     134599 (+1.41%) |     132469 (-0.19%)
libfourcc-cc0e8bf1-0.11.0-pre.so         |     125828   |     126084 (+0.20%) |     125827 (-0.00%)
libgetopts-c94737d1-0.11.0-pre.rlib      |     864664   |     853040 (-1.34%) |     862548 (-0.24%)
libgetopts-c94737d1-0.11.0-pre.so        |     158855   |     157425 (-0.90%) |     158275 (-0.37%)
libglob-eafe1d22-0.11.0-pre.rlib         |     951370   |     944674 (-0.70%) |     946734 (-0.49%)
libglob-eafe1d22-0.11.0-pre.so           |     159130   |     157385 (-1.10%) |     156791 (-1.47%)
libgraphviz-7b3cf89d-0.11.0-pre.rlib     |     269600   |     269062 (-0.20%) |     269560 (-0.01%)
libgraphviz-7b3cf89d-0.11.0-pre.so       |      53334   |      53176 (-0.30%) |      53337 (+0.01%)
libgreen-ca0d0b80-0.11.0-pre.rlib        |    1374120   |    1389510 (+1.12%) |    1361696 (-0.90%)
libgreen-ca0d0b80-0.11.0-pre.so          |     372435   |     377929 (+1.48%) |     370991 (-0.39%)
libhexfloat-3b978f48-0.11.0-pre.so       |     131926   |     132166 (+0.18%) |     131935 (+0.01%)
liblibc-4f9a876d-0.11.0-pre.rlib         |     617472   |     617472 (+0.00%) |     617472 (+0.00%)
liblog-cd053230-0.11.0-pre.rlib          |     371190   |     371048 (-0.04%) |     370836 (-0.10%)
liblog-cd053230-0.11.0-pre.so            |      85996   |      86020 (+0.03%) |      85781 (-0.25%)
libmorestack.a                           |       1388   |       1388 (+0.00%) |       1388 (+0.00%)
libnative-1fb5e2c0-0.11.0-pre.rlib       |    2233070   |    2264296 (+1.40%) |    2194920 (-1.71%)
libnative-1fb5e2c0-0.11.0-pre.so         |     635787   |     639341 (+0.56%) |     621184 (-2.30%)
libnum-ebe12db7-0.11.0-pre.rlib          |    2672318   |    2675292 (+0.11%) |    2669370 (-0.11%)
libnum-ebe12db7-0.11.0-pre.so            |     398924   |     399357 (+0.11%) |     395821 (-0.78%)
librand-2ea8f361-0.11.0-pre.rlib         |    1691108   |    1691696 (+0.03%) |    1690264 (-0.05%)
libregex-77385931-0.11.0-pre.rlib        |    2007348   |    2006050 (-0.06%) |    2003804 (-0.18%)
libregex-77385931-0.11.0-pre.so          |     450520   |     450790 (+0.06%) |     449535 (-0.22%)
libregex_macros-a2216dec-0.11.0-pre.so   |     597208   |     569004 (-4.72%) |     568800 (-4.76%)
librlibc-d1ece24e-0.11.0-pre.rlib        |      12394   |      12394 (+0.00%) |      12394 (+0.00%)
librustc-d252d482-0.11.0-pre.so          |   51582383   |   51230320 (-0.68%) |   50930784 (-1.26%)
librustdoc-6ecbf63e-0.11.0-pre.so        |    4557074   |    4501877 (-1.21%) |    4394506 (-3.57%)
librustuv-ede8cb89-0.11.0-pre.rlib       |    4774956   |    4791366 (+0.34%) |    4732386 (-0.89%)
librustuv-ede8cb89-0.11.0-pre.so         |    1401710   |    1400237 (-0.11%) |    1386869 (-1.06%)
libsemver-e49a2dee-0.11.0-pre.rlib       |     392704   |     392434 (-0.07%) |     392940 (+0.06%)
libsemver-e49a2dee-0.11.0-pre.so         |      71863   |      71847 (-0.02%) |      71860 (-0.00%)
libserialize-0352aab7-0.11.0-pre.rlib    |    8059698   |    8033972 (-0.32%) |    7989802 (-0.87%)
libserialize-0352aab7-0.11.0-pre.so      |    1126099   |    1115520 (-0.94%) |    1101721 (-2.16%)
libstd-59beb4f7-0.11.0-pre.rlib          |   18802728   |   18780212 (-0.12%) |   18743438 (-0.32%)
libstd-59beb4f7-0.11.0-pre.so            |    4499534   |    4488835 (-0.24%) |    4477677 (-0.49%)
libsync-305341d2-0.11.0-pre.rlib         |    1377062   |    1400190 (+1.68%) |    1369498 (-0.55%)
libsync-305341d2-0.11.0-pre.so           |     306762   |     312212 (+1.78%) |     304095 (-0.87%)
libsyntax-555559ea-0.11.0-pre.so         |    6703330   |    6632254 (-1.06%) |    6596295 (-1.60%)
libterm-4e4945a5-0.11.0-pre.rlib         |    1503928   |    1512648 (+0.58%) |    1495932 (-0.53%)
libterm-4e4945a5-0.11.0-pre.so           |     389380   |     392678 (+0.85%) |     385517 (-0.99%)
libtest-a79f950d-0.11.0-pre.rlib         |    3606962   |    3555410 (-1.43%) |    3589258 (-0.49%)
libtest-a79f950d-0.11.0-pre.so           |     740255   |     728398 (-1.60%) |     734521 (-0.77%)
libtime-4bb3739b-0.11.0-pre.rlib         |     847036   |     847178 (+0.02%) |     847194 (+0.02%)
libtime-4bb3739b-0.11.0-pre.so           |     131516   |     132829 (+1.00%) |     131518 (+0.00%)
liburl-b8b5640c-0.11.0-pre.rlib          |     647764   |     647558 (-0.03%) |     646896 (-0.13%)
liburl-b8b5640c-0.11.0-pre.so            |     146616   |     146621 (+0.00%) |     146531 (-0.06%)
libuuid-238d8f44-0.11.0-pre.rlib         |     359732   |     359682 (-0.01%) |     358936 (-0.22%)
libuuid-238d8f44-0.11.0-pre.so           |      77110   |      77110 (+0.00%) |      77023 (-0.11%)
total                                    |  237081476   |  236049893 (-0.44%) |  234752639 (-0.98%)


So running MergeFunc early like in the clang patch isn't nearly as good as running it late. I also tried to enable usage of global aliases instead of just thunks when merging functions, but that crashes.

Closes #8492

Copy only up to `min(new_size, old_size)` when doing reallocate.

This was a bug when running with jemalloc disabled.

Fix #16687

With no custom message, we should just use concat! + stringify! for
`assert!(expr)` to avoid the string formatting code path.

Inspired by issue #16625

These are somewhat stop-gap solutions to address #16625 

core: Separate failure formatting in str methods slice, slice_to, slice_from

Use a separate inline-never function to format failure message for
str::slice() errors.

Using strcat's idea, this makes sure no formatting code from failure is
inlined when str::slice() is inlined. The number of `unreachable` being
inlined when usingi `.slice()` drops from 5 to just 1.



The testcase:

```
#![crate_type = "lib"]
pub fn slice(x: &str, a: uint, b: uint) -> &str {
    x.slice(a, b)
}
```

shrinks from 16.9 kB to 3.3 kB llvm IR, and the number of `unreachable` drops from 5 to 1.

Also:

* Remove unseeming repetition.
* By now, the reader has already heard that Rust is safe by default, so
reduce the overlong sentence, making it easier to read.

Closes #10618
Closes #16382

Fixes #9536

First commit fixes issue regarding recognizing MSYS2 build.
Second commit fixes issue regarding MSYS/Windows paths.

I was doing a lot of parsing ascii strings, and the generic bsearch functions in `tables.rs` came up very high in the profile.
This should avoid calling those functions for simple ASCII range chars.

There is a check in TwoWaySearcher::new to determine whether the needle is periodic. This is needed because during searching when a match fails, we cannot advance the position by the entire length of the needle when it is periodic, but can only advance by the length of the period.

The reason "bananas".contains("nana") (and similar searches) were returning false was because the periodicity check was wrong.

Closes #16589

Also, thanks to @Gankro, who came up with many buggy examples.

Fix #16687

To avoid a compilation error when running the tests the function has to be public.

With no custom message, we should just use concat! + stringify! for
`assert!(expr)`.

Inspired by issue #16625