make vec fns/methods take imm slices.

this also repairs the unsoundness in typing of unpack_slice,
which was silently converting a const ptr to an imm one.

1 files changed, 7 insertions, 0 deletions

diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs
index eac3ed27934..e83c35f5ed8 100644
--- a/src/libcore/ptr.rs
+++ b/src/libcore/ptr.rs
@@ -3,6 +3,7 @@
 export addr_of;
 export mut_addr_of;
 export offset;
+export const_offset;
 export mut_offset;
 export null;
 export is_null;
@@ -45,6 +46,12 @@ fn offset<T>(ptr: *T, count: uint) -> *T unsafe {
     (ptr as uint + count * sys::size_of::<T>()) as *T
 }
 
+#[doc = "Calculate the offset from a const pointer"]
+#[inline(always)]
+fn const_offset<T>(ptr: *const T, count: uint) -> *const T unsafe {
+    (ptr as uint + count * sys::size_of::<T>()) as *T
+}
+
 #[doc = "Calculate the offset from a mut pointer"]
 #[inline(always)]
 fn mut_offset<T>(ptr: *mut T, count: uint) -> *mut T {