Add scope instead of drop

It seems that the compiler doesn't recognize the drop and complains
that the mutex crosses an await (introduced in later commit), even
though it doesn't.

Author: joostjager

lightning/src/events/bump_transaction.rs

@@ -413,51 +413,52 @@ where
 		tolerate_high_network_feerates: bool, target_feerate_sat_per_1000_weight: u32,
 		preexisting_tx_weight: u64, input_amount_sat: Amount, target_amount_sat: Amount,
 	) -> Result<CoinSelection, ()> {
-		let mut locked_utxos = self.locked_utxos.lock().unwrap();
-		let mut eligible_utxos = utxos.iter().filter_map(|utxo| {
-			if let Some(utxo_claim_id) = locked_utxos.get(&utxo.outpoint) {
-				if *utxo_claim_id != claim_id && !force_conflicting_utxo_spend {
-					log_trace!(self.logger, "Skipping UTXO {} to prevent conflicting spend", utxo.outpoint);
-					return None;
-				}
-			}
-			let fee_to_spend_utxo = Amount::from_sat(fee_for_weight(
-				target_feerate_sat_per_1000_weight, BASE_INPUT_WEIGHT + utxo.satisfaction_weight,
-			));
-			let should_spend = if tolerate_high_network_feerates {
-				utxo.output.value > fee_to_spend_utxo
-			} else {
-				utxo.output.value >= fee_to_spend_utxo * 2
-			};
-			if should_spend {
-				Some((utxo, fee_to_spend_utxo))
-			} else {
-				log_trace!(self.logger, "Skipping UTXO {} due to dust proximity after spend", utxo.outpoint);
-				None
-			}
-		}).collect::<Vec<_>>();
-		eligible_utxos.sort_unstable_by_key(|(utxo, _)| utxo.output.value);
-
 		let mut selected_amount = input_amount_sat;
 		let mut total_fees = Amount::from_sat(fee_for_weight(target_feerate_sat_per_1000_weight, preexisting_tx_weight));
 		let mut selected_utxos = Vec::new();
-		for (utxo, fee_to_spend_utxo) in eligible_utxos {
-			if selected_amount >= target_amount_sat + total_fees {
-				break;
+		{
+			let mut locked_utxos = self.locked_utxos.lock().unwrap();
+			let mut eligible_utxos = utxos.iter().filter_map(|utxo| {
+				if let Some(utxo_claim_id) = locked_utxos.get(&utxo.outpoint) {
+					if *utxo_claim_id != claim_id && !force_conflicting_utxo_spend {
+						log_trace!(self.logger, "Skipping UTXO {} to prevent conflicting spend", utxo.outpoint);
+						return None;
+					}
+				}
+				let fee_to_spend_utxo = Amount::from_sat(fee_for_weight(
+					target_feerate_sat_per_1000_weight, BASE_INPUT_WEIGHT + utxo.satisfaction_weight,
+				));
+				let should_spend = if tolerate_high_network_feerates {
+					utxo.output.value > fee_to_spend_utxo
+				} else {
+					utxo.output.value >= fee_to_spend_utxo * 2
+				};
+				if should_spend {
+					Some((utxo, fee_to_spend_utxo))
+				} else {
+					log_trace!(self.logger, "Skipping UTXO {} due to dust proximity after spend", utxo.outpoint);
+					None
+				}
+			}).collect::<Vec<_>>();
+			eligible_utxos.sort_unstable_by_key(|(utxo, _)| utxo.output.value);
+
+			for (utxo, fee_to_spend_utxo) in eligible_utxos {
+				if selected_amount >= target_amount_sat + total_fees {
+					break;
+				}
+				selected_amount += utxo.output.value;
+				total_fees += fee_to_spend_utxo;
+				selected_utxos.push(utxo.clone());
+			}
+			if selected_amount < target_amount_sat + total_fees {
+				log_debug!(self.logger, "Insufficient funds to meet target feerate {} sat/kW",
+					target_feerate_sat_per_1000_weight);
+				return Err(());
+			}
+			for utxo in &selected_utxos {
+				locked_utxos.insert(utxo.outpoint, claim_id);
 			}
-			selected_amount += utxo.output.value;
-			total_fees += fee_to_spend_utxo;
-			selected_utxos.push(utxo.clone());
-		}
-		if selected_amount < target_amount_sat + total_fees {
-			log_debug!(self.logger, "Insufficient funds to meet target feerate {} sat/kW",
-				target_feerate_sat_per_1000_weight);
-			return Err(());
-		}
-		for utxo in &selected_utxos {
-			locked_utxos.insert(utxo.outpoint, claim_id);
 		}
-		core::mem::drop(locked_utxos);
 
 		let remaining_amount = selected_amount - target_amount_sat - total_fees;
 		let change_script = self.source.get_change_script()?;