If T is DomainDecode, so is &mut T.

implementations/rust/preserves/src/value/domain.rs

@@ -23,6 +23,16 @@ pub trait DomainEncode<D: Embeddable> {
     ) -> io::Result<()>;
 }
 
+impl <'a, D: Embeddable, T: DomainDecode<D>> DomainDecode<D> for &'a mut T {
+    fn decode_embedded<'de, 'src, S: BinarySource<'de>>(
+        &mut self,
+        src: &'src mut S,
+        read_annotations: bool,
+    ) -> io::Result<D> {
+        (**self).decode_embedded(src, read_annotations)
+    }
+}
+
 pub struct IOValueDomainCodec;
 
 impl DomainDecode<IOValue> for IOValueDomainCodec {