Minor changes post review

Author: optout21

lightning/src/ln/channel.rs

@@ -2039,26 +2039,27 @@ impl<SP: Deref> PendingV2Channel<SP> where SP::Target: SignerProvider {
 	) -> Result<Option<InteractiveTxMessageSend>, APIError>
 	where ES::Target: EntropySource
 	{
-		let mut funding_inputs = self.dual_funding_context.our_funding_inputs.take().unwrap_or_else(|| vec![]);
+		let mut funding_inputs = Vec::new();
+		mem::swap(&mut self.dual_funding_context.our_funding_inputs, &mut funding_inputs);
 
 		if let Some(prev_funding_input) = prev_funding_input {
 			funding_inputs.push(prev_funding_input);
 		}
 
 		let mut funding_inputs_prev_outputs: Vec<&TxOut> = Vec::with_capacity(funding_inputs.len());
 		// Check that vouts exist for each TxIn in provided transactions.
-		for (idx, input) in funding_inputs.iter().enumerate() {
-			if let Some(output) = input.1.as_transaction().output.get(input.0.previous_output.vout as usize) {
-				funding_inputs_prev_outputs.push(&output);
+		for (idx, (txin, tx)) in funding_inputs.iter().enumerate() {
+			if let Some(output) = tx.as_transaction().output.get(txin.previous_output.vout as usize) {
+				funding_inputs_prev_outputs.push(output);
 			} else {
 				return Err(APIError::APIMisuseError {
 					err: format!("Transaction with txid {} does not have an output with vout of {} corresponding to TxIn at funding_inputs[{}]",
-						input.1.as_transaction().compute_txid(), input.0.previous_output.vout, idx) });
+						tx.as_transaction().compute_txid(), txin.previous_output.vout, idx) });
 			}
 		}
 
 		let total_input_satoshis: u64 = funding_inputs.iter().map(
-			|input| input.1.as_transaction().output.get(input.0.previous_output.vout as usize).map(|out| out.value.to_sat()).unwrap_or(0)
+			|(txin, tx)| tx.as_transaction().output.get(txin.previous_output.vout as usize).map(|out| out.value.to_sat()).unwrap_or(0)
 		).sum();
 		if total_input_satoshis < self.dual_funding_context.our_funding_satoshis {
 			return Err(APIError::APIMisuseError {
@@ -2100,8 +2101,14 @@ impl<SP: Deref> PendingV2Channel<SP> where SP::Target: SignerProvider {
 				|err| APIError::APIMisuseError {
 					err: format!("Failed to get change script as new destination script, {:?}", err),
 				})?;
-			add_funding_change_output(change_value, change_script,
-				&mut funding_outputs, self.dual_funding_context.funding_feerate_sat_per_1000_weight);
+			let mut change_output = TxOut {
+				value: Amount::from_sat(change_value),
+				script_pubkey: change_script,
+			};
+			let change_output_weight = get_output_weight(&change_output.script_pubkey).to_wu();
+			let change_output_fee = fee_for_weight(self.dual_funding_context.funding_feerate_sat_per_1000_weight, change_output_weight);
+			change_output.value = Amount::from_sat(change_value.saturating_sub(change_output_fee));
+			funding_outputs.push(OutputOwned::Single(change_output));
 		}
 
 		let constructor_args = InteractiveTxConstructorArgs {
@@ -2120,7 +2127,7 @@ impl<SP: Deref> PendingV2Channel<SP> where SP::Target: SignerProvider {
 			.map_err(|_| APIError::APIMisuseError { err: "Incorrect shared output provided".into() })?;
 		let msg = tx_constructor.take_initiator_first_message();
 
-		self.interactive_tx_constructor.replace(tx_constructor);
+		self.interactive_tx_constructor = Some(tx_constructor);
 
 		Ok(msg)
 	}
@@ -4563,21 +4570,6 @@ fn get_v2_channel_reserve_satoshis(channel_value_satoshis: u64, dust_limit_satos
 	cmp::min(channel_value_satoshis, cmp::max(q, dust_limit_satoshis))
 }
 
-#[allow(dead_code)] // TODO(dual_funding): Remove once begin_interactive_funding_tx_construction() is used
-fn add_funding_change_output(
-	change_value: u64, change_script: ScriptBuf,
-	funding_outputs: &mut Vec<OutputOwned>, funding_feerate_sat_per_1000_weight: u32,
-) {
-	let mut change_output = TxOut {
-		value: Amount::from_sat(change_value),
-		script_pubkey: change_script,
-	};
-	let change_output_weight = get_output_weight(&change_output.script_pubkey).to_wu();
-	let change_output_fee = fee_for_weight(funding_feerate_sat_per_1000_weight, change_output_weight);
-	change_output.value = Amount::from_sat(change_value.saturating_sub(change_output_fee));
-	funding_outputs.push(OutputOwned::Single(change_output.clone()));
-}
-
 pub(super) fn calculate_our_funding_satoshis(
 	is_initiator: bool, funding_inputs: &[(TxIn, TransactionU16LenLimited)],
 	total_witness_weight: Weight, funding_feerate_sat_per_1000_weight: u32,
@@ -4640,7 +4632,7 @@ pub(super) struct DualFundingChannelContext {
 	///
 	/// Note that this field may be emptied once the interactive negotiation has been started.
 	#[allow(dead_code)] // TODO(dual_funding): Remove once contribution to V2 channels is enabled.
-	pub our_funding_inputs: Option<Vec<(TxIn, TransactionU16LenLimited)>>,
+	pub our_funding_inputs: Vec<(TxIn, TransactionU16LenLimited)>,
 }
 
 impl DualFundingChannelContext {
@@ -9308,7 +9300,7 @@ impl<SP: Deref> PendingV2Channel<SP> where SP::Target: SignerProvider {
 			their_funding_satoshis: None,
 			funding_tx_locktime,
 			funding_feerate_sat_per_1000_weight,
-			our_funding_inputs: Some(funding_inputs),
+			our_funding_inputs: funding_inputs,
 		};
 		let chan = Self {
 			context,
@@ -9463,7 +9455,7 @@ impl<SP: Deref> PendingV2Channel<SP> where SP::Target: SignerProvider {
 			their_funding_satoshis: Some(msg.common_fields.funding_satoshis),
 			funding_tx_locktime: LockTime::from_consensus(msg.locktime),
 			funding_feerate_sat_per_1000_weight: msg.funding_feerate_sat_per_1000_weight,
-			our_funding_inputs: Some(funding_inputs.clone()),
+			our_funding_inputs: funding_inputs.clone(),
 		};
 
 		let interactive_tx_constructor = Some(InteractiveTxConstructor::new(