splice: Add funding outnum

Fixes #7005

Changelog-Changed: Added outnum of new funding output to splice_signed RPC command

.msggen.json

@@ -3113,6 +3113,7 @@
             "Splice_Signed.sign_first": 3
         },
         "Splice_signedResponse": {
+            "Splice_Signed.outnum": 3,
             "Splice_Signed.tx": 1,
             "Splice_Signed.txid": 2
         },
@@ -10788,6 +10789,10 @@
             "added": "pre-v0.10.1",
             "deprecated": false
         },
+        "Splice_Signed.outnum": {
+            "added": "v24.08",
+            "deprecated": false
+        },
         "Splice_Signed.psbt": {
             "added": "pre-v0.10.1",
             "deprecated": false

cln-grpc/proto/node.proto

@@ -2655,6 +2655,7 @@ message Splice_signedRequest {
 message Splice_signedResponse {
 	bytes tx = 1;
 	bytes txid = 2;
+	optional uint32 outnum = 3;
 }
 
 message Splice_updateRequest {

cln-grpc/src/convert.rs

@@ -2474,6 +2474,7 @@ impl From<responses::Splice_initResponse> for pb::SpliceInitResponse {
 impl From<responses::Splice_signedResponse> for pb::SpliceSignedResponse {
     fn from(c: responses::Splice_signedResponse) -> Self {
         Self {
+            outnum: c.outnum, // Rule #2 for type u32?
             tx: hex::decode(&c.tx).unwrap(), // Rule #2 for type hex
             txid: hex::decode(&c.txid).unwrap(), // Rule #2 for type txid
         }

cln-rpc/src/model.rs

@@ -8499,6 +8499,8 @@ pub mod responses {
 
 	#[derive(Clone, Debug, Deserialize, Serialize)]
 	pub struct Splice_signedResponse {
+	    #[serde(skip_serializing_if = "Option::is_none")]
+	    pub outnum: Option<u32>,
 	    pub tx: String,
 	    pub txid: String,
 	}

contrib/msggen/msggen/schema.json

@@ -28150,6 +28150,13 @@
             "description": [
               "The txid is of the final transaction."
             ]
+          },
+          "outnum": {
+            "added": "v24.08",
+            "type": "u32",
+            "description": [
+              "The index of the new funding output."
+            ]
           }
         }
       },

contrib/pyln-testing/pyln/testing/grpc2py.py

@@ -1947,6 +1947,7 @@ def splice_init2py(m):
 
 def splice_signed2py(m):
     return remove_default({
+        "outnum": m.outnum,  # PrimitiveField in generate_composite
         "tx": hexlify(m.tx),  # PrimitiveField in generate_composite
         "txid": hexlify(m.txid),  # PrimitiveField in generate_composite
     })

doc/schemas/lightning-splice_signed.json

@@ -54,6 +54,13 @@
         "description": [
           "The txid is of the final transaction."
         ]
+      },
+      "outnum": {
+        "added": "v24.08",
+        "type": "u32",
+        "description": [
+          "The index of the new funding output."
+        ]
       }
     }
   },

lightningd/channel_control.c

@@ -501,6 +501,7 @@ static void handle_tx_broadcast(struct send_splice_info *info)
 
 		json_add_hex(response, "tx", tx_bytes, tal_bytelen(tx_bytes));
 		json_add_txid(response, "txid", &txid);
+		json_add_u32(response, "outnum", info->output_index);
 
 		was_pending(command_success(info->cc->cmd, response));
 	}