Use boxed functions instead of transmute

... to convert between Box and raw pointers. E. g. use

```
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 in practice.

2 files changed, 7 insertions, 4 deletions

diff --git a/src/libstd/sys/windows/thread.rs b/src/libstd/sys/windows/thread.rs
index f3a27877e5c..7fe8dce1a3e 100644
--- a/src/libstd/sys/windows/thread.rs
+++ b/src/libstd/sys/windows/thread.rs
@@ -10,6 +10,8 @@
 
 use prelude::v1::*;
 
+use boxed;
+use boxed::Box;
 use cmp;
 use io;
 use mem;
@@ -45,7 +47,8 @@ pub mod guard {
 }
 
 pub unsafe fn create(stack: uint, p: Thunk) -> io::Result<rust_thread> {
-    let arg: *mut libc::c_void = mem::transmute(box p);
+    let raw_p = boxed::into_raw(box p);
+    let arg = raw_p as *mut libc::c_void;
     // FIXME On UNIX, we guard against stack sizes that are too small but
     // that's because pthreads enforces that stacks are at least
     // PTHREAD_STACK_MIN bytes big.  Windows has no such lower limit, it's
@@ -61,7 +64,7 @@ pub unsafe fn create(stack: uint, p: Thunk) -> io::Result<rust_thread> {
 
     if ret as uint == 0 {
         // be sure to not leak the closure
-        let _p: Box<Thunk> = mem::transmute(arg);
+        let _p: Box<Thunk> = Box::from_raw(raw_p);
         Err(io::Error::last_os_error())
     } else {
         Ok(ret)
diff --git a/src/libstd/sys/windows/thread_local.rs b/src/libstd/sys/windows/thread_local.rs
index 0c24ab1fa09..cf942b5d025 100644
--- a/src/libstd/sys/windows/thread_local.rs
+++ b/src/libstd/sys/windows/thread_local.rs
@@ -133,13 +133,13 @@ unsafe fn init_dtors() {
     if !DTORS.is_null() { return }
 
     let dtors = box Vec::<(Key, Dtor)>::new();
-    DTORS = mem::transmute(dtors);
+    DTORS = boxed::into_raw(dtors);
 
     rt::at_exit(move|| {
         DTOR_LOCK.lock();
         let dtors = DTORS;
         DTORS = ptr::null_mut();
-        mem::transmute::<_, Box<Vec<(Key, Dtor)>>>(dtors);
+        Boxed::from_raw(dtors);
         assert!(DTORS.is_null()); // can't re-init after destructing
         DTOR_LOCK.unlock();
     });