Auto merge of #35627 - apasel422:coerce-cell, r=alexcrichton

[rust.git] / src / libcore / cell.rs

diff --git a/src/libcore/cell.rs b/src/libcore/cell.rs
index a388012e1daf2cd80e69ed5b5bf5576949230206..2af48ef2fabe3b42d04cfa53bb4bd565259f538b 100644 (file)
--- a/src/libcore/cell.rs
+++ b/src/libcore/cell.rs
@@ -355,6 +355,9 @@ fn from(t: T) -> Cell<T> {
     }
 }
 
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<T: CoerceUnsized<U>, U> CoerceUnsized<Cell<U>> for Cell<T> {}
+
 /// A mutable memory location with dynamically checked borrow rules
 ///
 /// See the [module-level documentation](index.html) for more.
@@ -793,6 +796,9 @@ fn from(t: T) -> RefCell<T> {
     }
 }
 
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<T: CoerceUnsized<U>, U> CoerceUnsized<RefCell<U>> for RefCell<T> {}
+
 struct BorrowRef<'b> {
     borrow: &'b Cell<BorrowFlag>,
 }
@@ -1122,3 +1128,13 @@ fn from(t: T) -> UnsafeCell<T> {
         UnsafeCell::new(t)
     }
 }
+
+#[unstable(feature = "coerce_unsized", issue = "27732")]
+impl<T: CoerceUnsized<U>, U> CoerceUnsized<UnsafeCell<U>> for UnsafeCell<T> {}
+
+#[allow(unused)]
+fn assert_coerce_unsized(a: UnsafeCell<&i32>, b: Cell<&i32>, c: RefCell<&i32>) {
+    let _: UnsafeCell<&Send> = a;
+    let _: Cell<&Send> = b;
+    let _: RefCell<&Send> = c;
+}