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, 4 deletions

diff --git a/src/libstd/local_data.rs b/src/libstd/local_data.rs
index 5d18ca4141b..1a971594837 100644
--- a/src/libstd/local_data.rs
+++ b/src/libstd/local_data.rs
@@ -38,11 +38,11 @@ assert_eq!(*key_vector.get().unwrap(), ~[4]);
 // Casting 'Arcane Sight' reveals an overwhelming aura of Transmutation
 // magic.
 
-use cast;
 use iter::{Iterator};
 use kinds::Send;
 use kinds::marker;
 use mem::replace;
+use mem;
 use ops::{Drop, Deref};
 use option::{None, Option, Some};
 use owned::Box;
@@ -172,7 +172,7 @@ impl<T: 'static> KeyValue<T> {
         // anything.
         let newval = data.map(|d| {
             let d = box d as Box<LocalData>;
-            let d: Box<LocalData:Send> = unsafe { cast::transmute(d) };
+            let d: Box<LocalData:Send> = unsafe { mem::transmute(d) };
             (keyval, d, 0)
         });
 
@@ -188,8 +188,8 @@ impl<T: 'static> KeyValue<T> {
                 replace(map.get_mut(i), newval).map(|(_, data, _)| {
                     // Move `data` into transmute to get out the memory that it
                     // owns, we must free it manually later.
-                    let t: raw::TraitObject = unsafe { cast::transmute(data) };
-                    let alloc: Box<T> = unsafe { cast::transmute(t.data) };
+                    let t: raw::TraitObject = unsafe { mem::transmute(data) };
+                    let alloc: Box<T> = unsafe { mem::transmute(t.data) };
 
                     // Now that we own `alloc`, we can just move out of it as we
                     // would with any other data.