Allow creating IbcReceiveResponse without ack

CHANGELOG.md

@@ -66,12 +66,15 @@ and this project adheres to
   ([#1967])
 - cosmwasm-std: Replace `MockApi` with bech32 implementation. ([#1914])
 - cosmwasm-vm: Replace `MockApi` with bech32 implementation. ([#1914])
+- cosmwasm-std: Make `IbcReceiveResponse::acknowledgement` optional and add
+  `IbcReceiveResponse::without_ack` constructor. ([#1892])
 
 [#1874]: https://github.com/CosmWasm/cosmwasm/pull/1874
 [#1876]: https://github.com/CosmWasm/cosmwasm/pull/1876
 [#1879]: https://github.com/CosmWasm/cosmwasm/pull/1879
 [#1883]: https://github.com/CosmWasm/cosmwasm/pull/1883
 [#1884]: https://github.com/CosmWasm/cosmwasm/pull/1884
+[#1892]: https://github.com/CosmWasm/cosmwasm/pull/1892
 [#1898]: https://github.com/CosmWasm/cosmwasm/pull/1898
 [#1902]: https://github.com/CosmWasm/cosmwasm/pull/1902
 [#1914]: https://github.com/CosmWasm/cosmwasm/pull/1914

contracts/ibc-reflect-send/src/ibc.rs

@@ -1,5 +1,5 @@
 use cosmwasm_std::{
-    entry_point, from_json, to_json_binary, DepsMut, Env, Ibc3ChannelOpenResponse,
+    entry_point, from_json, to_json_binary, Binary, DepsMut, Env, Ibc3ChannelOpenResponse,
     IbcBasicResponse, IbcChannelCloseMsg, IbcChannelConnectMsg, IbcChannelOpenMsg,
     IbcChannelOpenResponse, IbcMsg, IbcOrder, IbcPacketAckMsg, IbcPacketReceiveMsg,
     IbcPacketTimeoutMsg, IbcReceiveResponse, Never, StdError, StdResult,
@@ -101,7 +101,7 @@ pub fn ibc_packet_receive(
     _env: Env,
     _packet: IbcPacketReceiveMsg,
 ) -> Result<IbcReceiveResponse, Never> {
-    Ok(IbcReceiveResponse::new(b"{}").add_attribute("action", "ibc_packet_ack"))
+    Ok(IbcReceiveResponse::new(Binary::from(b"{}")).add_attribute("action", "ibc_packet_ack"))
 }
 
 #[entry_point]

contracts/ibc-reflect/src/contract.rs

@@ -546,7 +546,8 @@ mod tests {
             res.events[0]
         );
         // acknowledgement is an error
-        let ack: AcknowledgementMsg<DispatchResponse> = from_json(res.acknowledgement).unwrap();
+        let ack: AcknowledgementMsg<DispatchResponse> =
+            from_json(res.acknowledgement.unwrap()).unwrap();
         assert_eq!(
             ack.unwrap_err(),
             "invalid packet: account channel-123 not found"
@@ -560,7 +561,7 @@ mod tests {
         let res = ibc_packet_receive(deps.as_mut(), mock_env(), msg).unwrap();
 
         // assert app-level success
-        let ack: AcknowledgementMsg<()> = from_json(res.acknowledgement).unwrap();
+        let ack: AcknowledgementMsg<()> = from_json(res.acknowledgement.unwrap()).unwrap();
         ack.unwrap();
 
         // and we dispatch the BankMsg via submessage
@@ -597,7 +598,8 @@ mod tests {
         // we didn't dispatch anything
         assert_eq!(0, res.messages.len());
         // acknowledgement is an error
-        let ack: AcknowledgementMsg<DispatchResponse> = from_json(res.acknowledgement).unwrap();
+        let ack: AcknowledgementMsg<DispatchResponse> =
+            from_json(res.acknowledgement.unwrap()).unwrap();
         assert_eq!(ack.unwrap_err(), "invalid packet: Error parsing into type ibc_reflect::msg::PacketMsg: unknown variant `reflect_code_id`, expected one of `dispatch`, `who_am_i`, `balances`, `panic`, `return_err`, `return_msgs`");
     }
 

contracts/ibc-reflect/tests/integration.rs

@@ -240,7 +240,7 @@ fn handle_dispatch_packet() {
     );
     // acknowledgement is an error
     let ack: AcknowledgementMsg<DispatchResponse> =
-        from_slice(&res.acknowledgement, DESERIALIZATION_LIMIT).unwrap();
+        from_slice(&res.acknowledgement.unwrap(), DESERIALIZATION_LIMIT).unwrap();
     assert_eq!(
         ack.unwrap_err(),
         "invalid packet: account channel-123 not found"
@@ -255,7 +255,7 @@ fn handle_dispatch_packet() {
 
     // assert app-level success
     let ack: AcknowledgementMsg<DispatchResponse> =
-        from_slice(&res.acknowledgement, DESERIALIZATION_LIMIT).unwrap();
+        from_slice(&res.acknowledgement.unwrap(), DESERIALIZATION_LIMIT).unwrap();
     ack.unwrap();
 
     // and we dispatch the BankMsg
@@ -293,6 +293,6 @@ fn handle_dispatch_packet() {
     assert_eq!(0, res.messages.len());
     // acknowledgement is an error
     let ack: AcknowledgementMsg<DispatchResponse> =
-        from_slice(&res.acknowledgement, DESERIALIZATION_LIMIT).unwrap();
+        from_slice(&res.acknowledgement.unwrap(), DESERIALIZATION_LIMIT).unwrap();
     assert_eq!(ack.unwrap_err(), "invalid packet: Error parsing into type ibc_reflect::msg::PacketMsg: unknown variant `reflect_code_id`, expected one of `dispatch`, `who_am_i`, `balances`, `panic`, `return_err`, `return_msgs`");
 }

packages/std/src/ibc.rs

@@ -601,8 +601,9 @@ impl<T> IbcBasicResponse<T> {
 #[non_exhaustive]
 pub struct IbcReceiveResponse<T = Empty> {
     /// The bytes we return to the contract that sent the packet.
-    /// This may represent a success or error of execution
-    pub acknowledgement: Binary,
+    /// This may represent a success or error of execution.
+    /// In case of `None`, no acknowledgement is written.
+    pub acknowledgement: Option<Binary>,
     /// Optional list of messages to pass. These will be executed in order.
     /// If the ReplyOn member is set, they will invoke this contract's `reply` entry point
     /// after execution. Otherwise, they act like "fire and forget".
@@ -633,11 +634,24 @@ impl<T> IbcReceiveResponse<T> {
     ///
     /// // 0x01 is a FungibleTokenPacketSuccess from ICS-20.
     /// let resp: IbcReceiveResponse = IbcReceiveResponse::new(StdAck::success(b"\x01"));
-    /// assert_eq!(resp.acknowledgement, b"{\"result\":\"AQ==\"}");
+    /// assert_eq!(resp.acknowledgement.unwrap(), b"{\"result\":\"AQ==\"}");
     /// ```
     pub fn new(ack: impl Into<Binary>) -> Self {
         Self {
-            acknowledgement: ack.into(),
+            acknowledgement: Some(ack.into()),
+            messages: vec![],
+            attributes: vec![],
+            events: vec![],
+        }
+    }
+
+    /// Creates a new response without an acknowledgement.
+    ///
+    /// This allows you to send the acknowledgement asynchronously later using [`IbcMsg::WriteAcknowledgement`].
+    /// If you want to send the acknowledgement immediately, use [`IbcReceiveResponse::new`].
+    pub fn without_ack() -> Self {
+        Self {
+            acknowledgement: None,
             messages: vec![],
             attributes: vec![],
             events: vec![],