core: Remove the cast module

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]

[breaking-change]

1 files changed, 11 insertions, 11 deletions

diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 4a53a064610..37edab99915 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -217,24 +217,24 @@ responding to errors that may occur while attempting to read the numbers.
 
 #![deny(unused_must_use)]
 
-use cast;
 use char::Char;
 use container::Container;
 use fmt;
 use int;
 use iter::Iterator;
 use libc;
+use mem::transmute;
 use ops::{BitOr, BitAnd, Sub};
-use os;
 use option::{Option, Some, None};
+use os;
 use owned::Box;
 use path::Path;
 use result::{Ok, Err, Result};
+use slice::{Vector, MutableVector, ImmutableVector};
 use str::{StrSlice, StrAllocating};
 use str;
 use uint;
 use unstable::finally::try_finally;
-use slice::{Vector, MutableVector, ImmutableVector};
 use vec::Vec;
 
 // Reexports
@@ -729,7 +729,7 @@ pub trait Reader {
     /// `f64`s are 8 byte, IEEE754 double-precision floating point numbers.
     fn read_be_f64(&mut self) -> IoResult<f64> {
         self.read_be_u64().map(|i| unsafe {
-            cast::transmute::<u64, f64>(i)
+            transmute::<u64, f64>(i)
         })
     }
 
@@ -738,7 +738,7 @@ pub trait Reader {
     /// `f32`s are 4 byte, IEEE754 single-precision floating point numbers.
     fn read_be_f32(&mut self) -> IoResult<f32> {
         self.read_be_u32().map(|i| unsafe {
-            cast::transmute::<u32, f32>(i)
+            transmute::<u32, f32>(i)
         })
     }
 
@@ -789,7 +789,7 @@ pub trait Reader {
     /// `f64`s are 8 byte, IEEE754 double-precision floating point numbers.
     fn read_le_f64(&mut self) -> IoResult<f64> {
         self.read_le_u64().map(|i| unsafe {
-            cast::transmute::<u64, f64>(i)
+            transmute::<u64, f64>(i)
         })
     }
 
@@ -798,7 +798,7 @@ pub trait Reader {
     /// `f32`s are 4 byte, IEEE754 single-precision floating point numbers.
     fn read_le_f32(&mut self) -> IoResult<f32> {
         self.read_le_u32().map(|i| unsafe {
-            cast::transmute::<u32, f32>(i)
+            transmute::<u32, f32>(i)
         })
     }
 
@@ -995,14 +995,14 @@ pub trait Writer {
     /// Write a big-endian IEEE754 double-precision floating-point (8 bytes).
     fn write_be_f64(&mut self, f: f64) -> IoResult<()> {
         unsafe {
-            self.write_be_u64(cast::transmute(f))
+            self.write_be_u64(transmute(f))
         }
     }
 
     /// Write a big-endian IEEE754 single-precision floating-point (4 bytes).
     fn write_be_f32(&mut self, f: f32) -> IoResult<()> {
         unsafe {
-            self.write_be_u32(cast::transmute(f))
+            self.write_be_u32(transmute(f))
         }
     }
 
@@ -1040,7 +1040,7 @@ pub trait Writer {
     /// (8 bytes).
     fn write_le_f64(&mut self, f: f64) -> IoResult<()> {
         unsafe {
-            self.write_le_u64(cast::transmute(f))
+            self.write_le_u64(transmute(f))
         }
     }
 
@@ -1048,7 +1048,7 @@ pub trait Writer {
     /// (4 bytes).
     fn write_le_f32(&mut self, f: f32) -> IoResult<()> {
         unsafe {
-            self.write_le_u32(cast::transmute(f))
+            self.write_le_u32(transmute(f))
         }
     }