This library has no shims which are actually needed on Windows now, so translate
that last easy one into Rust and then don't link it at all on Windows.

This commit also deprecates the `as_string` and `as_slice` free functions in the
`string` and `vec` modules.

It would skip the middle part if it was 0, displaying a number a 1000
times too small. The MB/s number next to it gave it away.

Fixed it looks like this:

```
test h ... bench:   1,000,129 ns/iter (+/- 4,730)
```

Example display:

```
running 9 tests
test a ... bench:           0 ns/iter (+/- 0)
test b ... bench:          52 ns/iter (+/- 0)
test c ... bench:          88 ns/iter (+/- 0)
test d ... bench:         618 ns/iter (+/- 111)
test e ... bench:       5,933 ns/iter (+/- 87)
test f ... bench:      59,280 ns/iter (+/- 1,052)
test g ... bench:     588,672 ns/iter (+/- 3,381)
test h ... bench:   5,894,227 ns/iter (+/- 303,489)
test i ... bench:  59,112,382 ns/iter (+/- 1,500,110)
```

Fixes #10953
Fixes #26109

The output of individual tests can be captured now so it's safe to use
colorized output even when running tests in parallel. Closes #782.

Helps prevent mixed content warnings if accessing docs over HTTPS.

Closes #25459

This commit is an implementation of [RFC 1040][rfc] which is a redesign of the
currently-unstable `Duration` type. The API of the type has been scaled back to
be more conservative and it also no longer supports negative durations.

[rfc]: https://github.com/rust-lang/rfcs/blob/master/text/1040-duration-reform.md

The inner `duration` module of the `time` module has now been hidden (as
`Duration` is reexported) and the feature name for this type has changed from
`std_misc` to `duration`. All APIs accepting durations have also been audited to
take a more flavorful feature name instead of `std_misc`.

Closes #24874

An automated script was run against the `.rs` and `.md` files,
subsituting every occurrence of `task` with `thread`. In the `.rs`
files, only the texts in the comment blocks were affected.

E.g. if `foo.rs` looks like

    #![feature(test)]
    extern crate test;

    #[bench]
    fn bar(b: &mut test::Bencher) {
        b.iter(|| {
            1
        })
    }

    #[test]
    fn baz() {}

    #[bench]
    fn qux(b: &mut test::Bencher) {
        b.iter(|| {
            panic!()
        })
    }

Then

    $ rustc --test foo.rs
    $ ./foo

    running 3 tests
    test baz ... ok
    test qux ... FAILED
    test bar ... ok

    failures:

    ---- qux stdout ----
    	thread 'qux' panicked at 'explicit panic', bench.rs:17

    failures:
        qux

    test result: FAILED. 2 passed; 1 failed; 0 ignored; 0 measured

    $ ./foo --bench ba

    running 2 tests
    test baz ... ignored
    test bar ... bench:        97 ns/iter (+/- 74)

    test result: ok. 0 passed; 0 failed; 1 ignored; 1 measured

In particular, the two benchmark are being run as tests in the default
mode.

This helps for the main distribution, since benchmarks are only run with
`PLEASE_BENCH=1`, which is rarely set (and never set on the test bots),
and helps for code-coverage tools: benchmarks are run and so don't count
as dead code.

Fixes #15842.

This commit removes all the old casting/generic traits from `std::num` that are
no longer in use by the standard library. This additionally removes the old
`strconv` module which has not seen much use in quite a long time. All generic
functionality has been supplanted with traits in the `num` crate and the
`strconv` module is supplanted with the [rust-strconv crate][rust-strconv].

[rust-strconv]: https://github.com/lifthrasiir/rust-strconv

This is a breaking change due to the removal of these deprecated crates, and the
alternative crates are listed above.

[breaking-change]

`s/([^\(\s]+\.)len\(\) [(?:!=)>] 0/!$1is_empty()/g`

for `Box<FnBox()>`. I found the alias was still handy because it is
shorter than the fully written type.

This is a [breaking-change]: convert code using `Invoke` to use `FnBox`,
which is usually pretty straight-forward. Code using thunk mostly works
if you change `Thunk::new => Box::new` and `foo.invoke(arg)` to
`foo(arg)`.

This commit cleans out a large amount of deprecated APIs from the standard
library and some of the facade crates as well, updating all users in the
compiler and in tests as it goes along.

* Marks `#[stable]` the contents of the `std::convert` module.

* Added methods `PathBuf::as_path`, `OsString::as_os_str`,
  `String::as_str`, `Vec::{as_slice, as_mut_slice}`.

* Deprecates `OsStr::from_str` in favor of a new, stable, and more
  general `OsStr::new`.

* Adds unstable methods `OsString::from_bytes` and `OsStr::{to_bytes,
  to_cstring}` for ergonomic FFI usage.

[breaking-change]

Now that support has been removed, all lingering use cases are renamed.

This permits all coercions to be performed in casts, but adds lints to warn in those cases.

Part of this patch moves cast checking to a later stage of type checking. We acquire obligations to check casts as part of type checking where we previously checked them. Once we have type checked a function or module, then we check any cast obligations which have been acquired. That means we have more type information available to check casts (this was crucial to making coercions work properly in place of some casts), but it means that casts cannot feed input into type inference.

[breaking change]

* Adds two new lints for trivial casts and trivial numeric casts, these are warn by default, but can cause errors if you build with warnings as errors. Previously, trivial numeric casts and casts to trait objects were allowed.
* The unused casts lint has gone.
* Interactions between casting and type inference have changed in subtle ways. Two ways this might manifest are:
- You may need to 'direct' casts more with extra type information, for example, in some cases where `foo as _ as T` succeeded, you may now need to specify the type for `_`
- Casts do not influence inference of integer types. E.g., the following used to type check:

```
let x = 42;
let y = &x as *const u32;
```

Because the cast would inform inference that `x` must have type `u32`. This no longer applies and the compiler will fallback to `i32` for `x` and thus there will be a type error in the cast. The solution is to add more type information:

```
let x: u32 = 42;
let y = &x as *const u32;
```

This commit:

* Introduces `std::convert`, providing an implementation of
RFC 529.

* Deprecates the `AsPath`, `AsOsStr`, and `IntoBytes` traits, all
in favor of the corresponding generic conversion traits.

  Consequently, various IO APIs now take `AsRef<Path>` rather than
`AsPath`, and so on. Since the types provided by `std` implement both
traits, this should cause relatively little breakage.

* Deprecates many `from_foo` constructors in favor of `from`.

* Changes `PathBuf::new` to take no argument (creating an empty buffer,
  as per convention). The previous behavior is now available as
  `PathBuf::from`.

* De-stabilizes `IntoCow`. It's not clear whether we need this separate trait.

Closes #22751
Closes #14433

[breaking-change]

As @alexcrichton says, this was really a libgreen thing, and isn't
relevant now.

As this removes a technically-public function, this is a

[breaking-change]

Conflicts:
	src/libtest/lib.rs

We don't use 'task' anymore, these are now threads.

Because this changes the name of a compiler option, this is

[breaking-change]

The [associated RFC][rfc] for possibly splitting out `flush` has been closed and
as a result there are no more blockers for stabilizing this method, so this
commit marks the method as such.

[rfc]: https://github.com/rust-lang/rfcs/pull/950

This reverts commit bce7a6f4.