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, 4 insertions, 5 deletions

diff --git a/src/libgreen/basic.rs b/src/libgreen/basic.rs
index eba15e6e6d5..9e42e2f67c4 100644
--- a/src/libgreen/basic.rs
+++ b/src/libgreen/basic.rs
@@ -15,8 +15,7 @@
 //! This implementation is also used as the fallback implementation of an event
 //! loop if no other one is provided (and M:N scheduling is desired).
 
-use std::cast;
-use std::mem::replace;
+use std::mem;
 use std::rt::rtio::{EventLoop, IoFactory, RemoteCallback};
 use std::rt::rtio::{PausableIdleCallback, Callback};
 use std::unstable::sync::Exclusive;
@@ -50,7 +49,7 @@ impl BasicLoop {
     /// Process everything in the work queue (continually)
     fn work(&mut self) {
         while self.work.len() > 0 {
-            for work in replace(&mut self.work, vec![]).move_iter() {
+            for work in mem::replace(&mut self.work, vec![]).move_iter() {
                 work();
             }
         }
@@ -60,7 +59,7 @@ impl BasicLoop {
         let messages = unsafe {
             self.messages.with(|messages| {
                 if messages.len() > 0 {
-                    Some(replace(messages, vec![]))
+                    Some(mem::replace(messages, vec![]))
                 } else {
                     None
                 }
@@ -145,7 +144,7 @@ impl EventLoop for BasicLoop {
         let callback = box BasicPausable::new(self, cb);
         rtassert!(self.idle.is_none());
         unsafe {
-            let cb_ptr: &*mut BasicPausable = cast::transmute(&callback);
+            let cb_ptr: &*mut BasicPausable = mem::transmute(&callback);
             self.idle = Some(*cb_ptr);
         }
         callback as Box<PausableIdleCallback:Send>