Persist FundedChannel::pending_splice

Once a splice funding transaction has been constructed, the
corresponding state must be persisted so that the process can be
continued across restarts. This includes exchanging signatures, waiting
for enough confirmations, and RBF'ing.

Author: jkczyz

lightning/src/ln/channel.rs

@@ -2563,6 +2563,13 @@ struct PendingFunding {
 	received_funding_txid: Option<Txid>,
 }
 
+impl_writeable_tlv_based!(PendingFunding, {
+	(1, funding_negotiation, upgradable_option),
+	(3, negotiated_candidates, required_vec),
+	(5, sent_funding_txid, option),
+	(7, received_funding_txid, option),
+});
+
 enum FundingNegotiation {
 	AwaitingAck {
 		context: FundingNegotiationContext,
@@ -2576,6 +2583,13 @@ enum FundingNegotiation {
 	},
 }
 
+impl_writeable_tlv_based_enum_upgradable!(FundingNegotiation,
+	(0, AwaitingSignatures) => {
+		(1, funding, required),
+	},
+	unread_variants: AwaitingAck, ConstructingTransaction
+);
+
 impl FundingNegotiation {
 	fn as_funding(&self) -> Option<&FundingScope> {
 		match self {
@@ -14294,6 +14308,7 @@ where
 			(60, self.context.historical_scids, optional_vec), // Added in 0.2
 			(61, fulfill_attribution_data, optional_vec), // Added in 0.2
 			(63, holder_commitment_point_current, option), // Added in 0.2
+			(64, self.pending_splice, option), // Added in 0.2
 			(65, self.quiescent_action, option), // Added in 0.2
 		});
 
@@ -14655,6 +14670,7 @@ where
 
 		let mut minimum_depth_override: Option<u32> = None;
 
+		let mut pending_splice: Option<PendingFunding> = None;
 		let mut quiescent_action = None;
 
 		read_tlv_fields!(reader, {
@@ -14699,6 +14715,7 @@ where
 			(60, historical_scids, optional_vec), // Added in 0.2
 			(61, fulfill_attribution_data, optional_vec), // Added in 0.2
 			(63, holder_commitment_point_current_opt, option), // Added in 0.2
+			(64, pending_splice, option), // Added in 0.2
 			(65, quiescent_action, upgradable_option), // Added in 0.2
 		});
 
@@ -15059,7 +15076,7 @@ where
 			},
 			interactive_tx_signing_session,
 			holder_commitment_point,
-			pending_splice: None,
+			pending_splice,
 			quiescent_action,
 		})
 	}