Auto merge of #28197 - petrochenkov:borrow, r=alexcrichton

src/libcore/array.rs

@@ -19,6 +19,7 @@
                       integer constants",
             issue = "27778")]
 
+use borrow::{Borrow, BorrowMut};
 use clone::Clone;
 use cmp::{PartialEq, Eq, PartialOrd, Ord, Ordering};
 use convert::{AsRef, AsMut};
@@ -70,6 +71,20 @@ macro_rules! array_impls {
                 }
             }
 
+            #[stable(feature = "array_borrow", since = "1.4.0")]
+            impl<T> Borrow<[T]> for [T; $N] {
+                fn borrow(&self) -> &[T] {
+                    self
+                }
+            }
+
+            #[stable(feature = "array_borrow", since = "1.4.0")]
+            impl<T> BorrowMut<[T]> for [T; $N] {
+                fn borrow_mut(&mut self) -> &mut [T] {
+                    self
+                }
+            }
+
             #[stable(feature = "rust1", since = "1.0.0")]
             impl<T:Copy> Clone for [T; $N] {
                 fn clone(&self) -> [T; $N] {