Deserialize unsized Arc and Rc

serde/src/de/impls.rs

@@ -1112,10 +1112,10 @@ forwarded_impl!((T), Box<[T]>, Vec::into_boxed_slice);
 #[cfg(any(feature = "std", feature = "alloc"))]
 forwarded_impl!((), Box<str>, String::into_boxed_str);
 
-#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
+#[cfg(all(not(feature = "unstable"), feature = "rc", any(feature = "std", feature = "alloc")))]
 forwarded_impl!((T), Arc<T>, Arc::new);
 
-#[cfg(all(feature = "rc", any(feature = "std", feature = "alloc")))]
+#[cfg(all(not(feature = "unstable"), feature = "rc", any(feature = "std", feature = "alloc")))]
 forwarded_impl!((T), Rc<T>, Rc::new);
 
 #[cfg(any(feature = "std", feature = "alloc"))]
@@ -1135,6 +1135,31 @@ where
 
 ////////////////////////////////////////////////////////////////////////////////
 
+#[cfg(all(feature = "unstable", feature = "rc", any(feature = "std", feature = "alloc")))]
+macro_rules! box_forwarded_impl {
+    ($t:ident) => {
+        impl<'de, T: ?Sized> Deserialize<'de> for $t<T>
+        where
+            Box<T>: Deserialize<'de>,
+        {
+            fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+            where
+                D: Deserializer<'de>,
+            {
+                Box::deserialize(deserializer).map(Into::into)
+            }
+        }
+    }
+}
+
+#[cfg(all(feature = "unstable", feature = "rc", any(feature = "std", feature = "alloc")))]
+box_forwarded_impl!(Rc);
+
+#[cfg(all(feature = "unstable", feature = "rc", any(feature = "std", feature = "alloc")))]
+box_forwarded_impl!(Arc);
+
+////////////////////////////////////////////////////////////////////////////////
+
 impl<'de, T> Deserialize<'de> for Cell<T>
 where
     T: Deserialize<'de> + Copy,

test_suite/tests/test_de.rs

@@ -15,6 +15,8 @@ use std::path::{Path, PathBuf};
 use std::time::{Duration, UNIX_EPOCH};
 use std::default::Default;
 use std::ffi::{CString, OsString};
+use std::rc::Rc;
+use std::sync::Arc;
 
 #[cfg(feature = "unstable")]
 use std::ffi::CStr;
@@ -740,6 +742,40 @@ declare_tests! {
             Token::Bytes(b"abc"),
         ],
     }
+    test_rc {
+        Rc::new(true) => &[
+            Token::Bool(true),
+        ],
+    }
+    test_arc {
+        Arc::new(true) => &[
+            Token::Bool(true),
+        ],
+    }
+}
+
+#[cfg(feature = "unstable")]
+declare_tests! {
+    test_rc_dst {
+        Rc::<str>::from("s") => &[
+            Token::Str("s"),
+        ],
+        Rc::<[bool]>::from(&[true][..]) => &[
+            Token::Seq { len: Some(1) },
+            Token::Bool(true),
+            Token::SeqEnd,
+        ],
+    }
+    test_arc_dst {
+        Arc::<str>::from("s") => &[
+            Token::Str("s"),
+        ],
+        Arc::<[bool]>::from(&[true][..]) => &[
+            Token::Seq { len: Some(1) },
+            Token::Bool(true),
+            Token::SeqEnd,
+        ],
+    }
 }
 
 #[cfg(unix)]