Deprecate the DataClone trait

We'll replace `DataClone` with a trait alias once that feature becomes
available on stable.

src/data_traits.rs

@@ -133,8 +133,10 @@ pub unsafe trait DataMut : Data + DataRawMut {
 /// accessed with safe code.
 ///
 /// ***Internal trait, see `Data`.***
+#[deprecated(note="use `Data + DataRawClone` instead", since="0.12.1")]
 pub trait DataClone : Data + DataRawClone {}
 
+#[allow(deprecated)]
 impl<T> DataClone for T where T: Data + DataRawClone {}
 
 unsafe impl<A> DataRaw for RawViewRepr<*const A> {
@@ -387,7 +389,7 @@ pub unsafe trait DataOwned : Data {
 /// A representation that is a lightweight view.
 ///
 /// ***Internal trait, see `Data`.***
-pub unsafe trait DataShared : Clone + DataClone { }
+pub unsafe trait DataShared : Clone + Data + DataRawClone { }
 
 unsafe impl<A> DataShared for OwnedRcRepr<A> {}
 unsafe impl<'a, A> DataShared for ViewRepr<&'a A> {}

src/lib.rs

@@ -151,6 +151,7 @@ mod data_traits;
 
 pub use aliases::*;
 
+#[allow(deprecated)]
 pub use data_traits::{
     DataRaw,
     DataRawMut,