Rollup merge of #22696 - stepancheg:use-box, r=alexcrichton

 e. g.

```
let b: Box<Foo> = Box::from_raw(p);
```

instead of

```
let b: Box<Foo> = mem::transmute(p);
```

Patch also changes closure release code in `src/libstd/sys/unix/thread.rs`
when `pthread_create` failed. Raw pointer was transmuted to box of
`FnOnce()` instead of `Thunk`. This code was probably never executed,
because `pthread_create` rarely fails.

(And there are two more patches in PR: fix typo in doc and mark `from_raw` and `into_raw` functions inline.)

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index 2f9577c08de..0726704056e 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -388,7 +388,7 @@ impl<T> Vec<T> {
     pub fn into_boxed_slice(mut self) -> Box<[T]> {
         self.shrink_to_fit();
         unsafe {
-            let xs: Box<[T]> = mem::transmute(&mut *self);
+            let xs: Box<[T]> = Box::from_raw(&mut *self);
             mem::forget(self);
             xs
         }