Address comments

concordium-cis2/src/lib.rs

@@ -1246,7 +1246,7 @@ pub struct OnReceivingCis2Params<T, A> {
     pub amount:   A,
     /// The previous owner of the tokens.
     pub from:     Address,
-    /// Some extra information which where sent as part of the transfer.
+    /// Some extra information which was sent as part of the transfer.
     pub data:     AdditionalData,
 }
 
@@ -1262,7 +1262,7 @@ pub struct OnReceivingCis2DataParams<T, A, D> {
     pub amount:   A,
     /// The previous owner of the tokens.
     pub from:     Address,
-    /// Some extra information which where sent as part of the transfer.
+    /// Some extra information which was sent as part of the transfer.
     pub data:     D,
 }
 
@@ -1286,8 +1286,8 @@ impl<T: Serial, A: Serial, D: Serial> Serial for OnReceivingCis2DataParams<T, A,
         self.token_id.serial(out)?;
         self.amount.serial(out)?;
         self.from.serial(out)?;
-        (to_bytes(&self.data).len() as u16).serial(out)?;
-        out.write_all(&to_bytes(&self.data))?;
+        let add = AdditionalData(to_bytes(&self.data));
+        add.serial(out)?;
         Ok(())
     }
 }

examples/sponsored-tx-enabled-auction/src/lib.rs

@@ -474,3 +474,15 @@ fn view_item_state(ctx: &ReceiveContext, host: &Host<State>) -> ContractResult<I
     let item = host.state().items.get(&item_index).map(|x| x.to_owned()).ok_or(Error::NoItem)?;
     Ok(item)
 }
+
+/// Helper function that can be invoked at the front-end to serialize the
+/// `AdditionalDataIndex` before generating the message to be signed in the
+/// wallet.
+#[receive(
+    contract = "sponsored_tx_enabled_auction",
+    name = "serializationHelper",
+    parameter = "AdditionalDataIndex"
+)]
+fn contract_serialization_helper(_ctx: &ReceiveContext, _host: &Host<State>) -> ContractResult<()> {
+    Ok(())
+}