auto merge of #14069 : alexcrichton/rust/cast-module, r=brson

This commit revisits the `cast` module in libcore and libstd, and scrutinizes
all functions inside of it. The result was to remove the `cast` module entirely,
folding all functionality into the `mem` module. Specifically, this is the fate
of each function in the `cast` module.

* transmute - This function was moved to `mem`, but it is now marked as
              #[unstable]. This is due to planned changes to the `transmute`
              function and how it can be invoked (see the #[unstable] comment).
              For more information, see RFC 5 and #12898

* transmute_copy - This function was moved to `mem`, with clarification that is
                   is not an error to invoke it with T/U that are different
                   sizes, but rather that it is strongly discouraged. This
                   function is now #[stable]

* forget - This function was moved to `mem` and marked #[stable]

* bump_box_refcount - This function was removed due to the deprecation of
                      managed boxes as well as its questionable utility.

* transmute_mut - This function was previously deprecated, and removed as part
                  of this commit.

* transmute_mut_unsafe - This function doesn't serve much of a purpose when it
                         can be achieved with an `as` in safe code, so it was
                         removed.

* transmute_lifetime - This function was removed because it is likely a strong
                       indication that code is incorrect in the first place.

* transmute_mut_lifetime - This function was removed for the same reasons as
                           `transmute_lifetime`

* copy_lifetime - This function was moved to `mem`, but it is marked
                  `#[unstable]` now due to the likelihood of being removed in
                  the future if it is found to not be very useful.

* copy_mut_lifetime - This function was also moved to `mem`, but had the same
                      treatment as `copy_lifetime`.

* copy_lifetime_vec - This function was removed because it is not used today,
                      and its existence is not necessary with DST
                      (copy_lifetime will suffice).

In summary, the cast module was stripped down to these functions, and then the
functions were moved to the `mem` module.

    transmute - #[unstable]
    transmute_copy - #[stable]
    forget - #[stable]
    copy_lifetime - #[unstable]
    copy_mut_lifetime - #[unstable]

1 files changed, 6 insertions, 6 deletions

diff --git a/src/libnative/task.rs b/src/libnative/task.rs
index d5b02dc007b..4183dec19d0 100644
--- a/src/libnative/task.rs
+++ b/src/libnative/task.rs
@@ -15,7 +15,7 @@
 //! in order to spawn new tasks and deschedule the current task.
 
 use std::any::Any;
-use std::cast;
+use std::mem;
 use std::rt::bookkeeping;
 use std::rt::env;
 use std::rt::local::Local;
@@ -169,7 +169,7 @@ impl rt::Runtime for Ops {
     // for both tasks because these operations are all done inside of a mutex.
     //
     // You'll also find that if blocking fails (the `f` function hands the
-    // BlockedTask back to us), we will `cast::forget` the handles. The
+    // BlockedTask back to us), we will `mem::forget` the handles. The
     // reasoning for this is the same logic as above in that the task silently
     // transfers ownership via the `uint`, not through normal compiler
     // semantics.
@@ -198,7 +198,7 @@ impl rt::Runtime for Ops {
                             guard.wait();
                         }
                     }
-                    Err(task) => { cast::forget(task.wake()); }
+                    Err(task) => { mem::forget(task.wake()); }
                 }
             } else {
                 let iter = task.make_selectable(times);
@@ -217,7 +217,7 @@ impl rt::Runtime for Ops {
                     Some(task) => {
                         match task.wake() {
                             Some(task) => {
-                                cast::forget(task);
+                                mem::forget(task);
                                 (*me).awoken = true;
                             }
                             None => {}
@@ -229,7 +229,7 @@ impl rt::Runtime for Ops {
                 }
             }
             // re-acquire ownership of the task
-            cur_task = cast::transmute(cur_task_dupe);
+            cur_task = mem::transmute(cur_task_dupe);
         }
 
         // put the task back in TLS, and everything is as it once was.
@@ -242,7 +242,7 @@ impl rt::Runtime for Ops {
         unsafe {
             let me = &mut *self as *mut Ops;
             to_wake.put_runtime(self);
-            cast::forget(to_wake);
+            mem::forget(to_wake);
             let guard = (*me).lock.lock();
             (*me).awoken = true;
             guard.signal();