refactor NonZero, Shared, and Unique APIs

Major difference is that I removed Deref impls, as apparently LLVM has
trouble maintaining metadata with a `&ptr -> &ptr` API. This was cited
as a blocker for ever stabilizing this API. It wasn't that ergonomic
anyway.

* Added `get` to NonZero to replace Deref impl
* Added `as_ptr` to Shared/Unique to replace Deref impl
* Added Unique's `as_ref` and `as_mut` conveniences to Shared
* Added `::empty()` convenience constructor for Unique/Shared
* Deprecated `as_mut_ptr` on Shared in favour of `as_ptr`
* Improved documentation of types

Note that Shared now only refers to *mut, and not *const

1 files changed, 4 insertions, 9 deletions

diff --git a/src/libcore/nonzero.rs b/src/libcore/nonzero.rs
index d7382501bc3..d93085e96db 100644
--- a/src/libcore/nonzero.rs
+++ b/src/libcore/nonzero.rs
@@ -13,7 +13,7 @@
             reason = "needs an RFC to flesh out the design",
             issue = "27730")]
 
-use ops::{CoerceUnsized, Deref};
+use ops::CoerceUnsized;
 
 /// Unsafe trait to indicate what types are usable with the NonZero struct
 pub unsafe trait Zeroable {}
@@ -46,15 +46,10 @@ impl<T: Zeroable> NonZero<T> {
     pub const unsafe fn new(inner: T) -> NonZero<T> {
         NonZero(inner)
     }
-}
-
-impl<T: Zeroable> Deref for NonZero<T> {
-    type Target = T;
 
-    #[inline]
-    fn deref(&self) -> &T {
-        let NonZero(ref inner) = *self;
-        inner
+    /// Gets the inner value.
+    pub fn get(self) -> T {
+        self.0
     }
 }