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, 5 insertions, 6 deletions

diff --git a/src/libstd/rt/args.rs b/src/libstd/rt/args.rs
index df0f1d8d449..95d0eabd336 100644
--- a/src/libstd/rt/args.rs
+++ b/src/libstd/rt/args.rs
@@ -40,7 +40,7 @@ pub unsafe fn init(argc: int, argv: **u8) { realargs::init(argc, argv) }
 #[cfg(not(test))] pub fn take() -> Option<Vec<~[u8]>> { imp::take() }
 #[cfg(test)]      pub fn take() -> Option<Vec<~[u8]>> {
     match realargs::take() {
-        realstd::option::Some(v) => Some(unsafe{ ::cast::transmute(v) }),
+        realstd::option::Some(v) => Some(unsafe{ ::mem::transmute(v) }),
         realstd::option::None => None,
     }
 }
@@ -49,13 +49,13 @@ pub unsafe fn init(argc: int, argv: **u8) { realargs::init(argc, argv) }
 ///
 /// It is an error if the arguments already exist.
 #[cfg(not(test))] pub fn put(args: Vec<~[u8]>) { imp::put(args) }
-#[cfg(test)]      pub fn put(args: Vec<~[u8]>) { realargs::put(unsafe { ::cast::transmute(args) }) }
+#[cfg(test)]      pub fn put(args: Vec<~[u8]>) { realargs::put(unsafe { ::mem::transmute(args) }) }
 
 /// Make a clone of the global arguments.
 #[cfg(not(test))] pub fn clone() -> Option<Vec<~[u8]>> { imp::clone() }
 #[cfg(test)]      pub fn clone() -> Option<Vec<~[u8]>> {
     match realargs::clone() {
-        realstd::option::Some(v) => Some(unsafe { ::cast::transmute(v) }),
+        realstd::option::Some(v) => Some(unsafe { ::mem::transmute(v) }),
         realstd::option::None => None,
     }
 }
@@ -64,10 +64,9 @@ pub unsafe fn init(argc: int, argv: **u8) { realargs::init(argc, argv) }
 #[cfg(target_os = "android")]
 #[cfg(target_os = "freebsd")]
 mod imp {
-    use cast;
     use clone::Clone;
-    use option::{Option, Some, None};
     use iter::Iterator;
+    use option::{Option, Some, None};
     use owned::Box;
     use unstable::mutex::{StaticNativeMutex, NATIVE_MUTEX_INIT};
     use mem;
@@ -120,7 +119,7 @@ mod imp {
     }
 
     fn get_global_ptr() -> *mut Option<Box<Vec<~[u8]>>> {
-        unsafe { cast::transmute(&global_args_ptr) }
+        unsafe { mem::transmute(&global_args_ptr) }
     }
 
     // Copied from `os`.