Add impls for Rc<[T]> and Arc<[T]> (#552)

src/features/impl_alloc.rs

@@ -435,6 +435,26 @@ where
     }
 }
 
+impl<T> Decode for Rc<[T]>
+where
+    T: Decode,
+{
+    fn decode<D: Decoder>(decoder: &mut D) -> Result<Self, DecodeError> {
+        let vec = Vec::decode(decoder)?;
+        Ok(vec.into())
+    }
+}
+
+impl<'de, T> BorrowDecode<'de> for Rc<[T]>
+where
+    T: BorrowDecode<'de> + 'de,
+{
+    fn borrow_decode<D: BorrowDecoder<'de>>(decoder: &mut D) -> Result<Self, DecodeError> {
+        let vec = Vec::borrow_decode(decoder)?;
+        Ok(vec.into())
+    }
+}
+
 #[cfg(target_has_atomic = "ptr")]
 impl<T> Decode for Arc<T>
 where
@@ -482,3 +502,25 @@ where
         T::encode(self, encoder)
     }
 }
+
+#[cfg(target_has_atomic = "ptr")]
+impl<T> Decode for Arc<[T]>
+where
+    T: Decode,
+{
+    fn decode<D: Decoder>(decoder: &mut D) -> Result<Self, DecodeError> {
+        let vec = Vec::decode(decoder)?;
+        Ok(vec.into())
+    }
+}
+
+#[cfg(target_has_atomic = "ptr")]
+impl<'de, T> BorrowDecode<'de> for Arc<[T]>
+where
+    T: BorrowDecode<'de> + 'de,
+{
+    fn borrow_decode<D: BorrowDecoder<'de>>(decoder: &mut D) -> Result<Self, DecodeError> {
+        let vec = Vec::borrow_decode(decoder)?;
+        Ok(vec.into())
+    }
+}

tests/alloc.rs

@@ -89,9 +89,12 @@ fn test_alloc_commons() {
     {
         // Serde doesn't support Rc or Arc
         the_same(Rc::<u32>::new(5));
+        the_same(Rc::<[u32]>::from(vec![1, 2, 3, 4, 5]));
+
         #[cfg(target_has_atomic = "ptr")]
         {
             the_same(Arc::<u32>::new(5));
+            the_same(Arc::<[u32]>::from(vec![1, 2, 3, 4, 5]));
         }
     }