Drop Deref indirection for OutputSpender

Reduces generics and verbosity across the codebase, should provide equivalent
behavior.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: valentinewallace

lightning-background-processor/src/lib.rs

@@ -946,7 +946,7 @@ pub async fn process_events_async<
 	PM: Deref,
 	LM: Deref,
 	D: Deref,
-	O: Deref,
+	O: OutputSpender,
 	K: KVStore,
 	OS: Deref<Target = OutputSweeper<T, D, F, CF, K, L, O>>,
 	S: Deref<Target = SC>,
@@ -967,7 +967,6 @@ where
 	OM::Target: AOnionMessenger,
 	PM::Target: APeerManager,
 	LM::Target: ALiquidityManager,
-	O::Target: OutputSpender,
 	D::Target: ChangeDestinationSource,
 {
 	let async_event_handler = |event| {
@@ -1441,7 +1440,7 @@ pub async fn process_events_async_with_kv_store_sync<
 	PM: Deref,
 	LM: Deref,
 	D: Deref,
-	O: Deref,
+	O: OutputSpender,
 	K: Deref,
 	OS: Deref<Target = OutputSweeperSync<T, D, F, CF, K, L, O>>,
 	S: Deref<Target = SC>,
@@ -1462,7 +1461,6 @@ where
 	OM::Target: AOnionMessenger,
 	PM::Target: APeerManager,
 	LM::Target: ALiquidityManager,
-	O::Target: OutputSpender,
 	D::Target: ChangeDestinationSourceSync,
 	K::Target: KVStoreSync,
 {
@@ -1556,7 +1554,7 @@ impl BackgroundProcessor {
 		S: 'static + Deref<Target = SC> + Send + Sync,
 		SC: for<'b> WriteableScore<'b>,
 		D: 'static + Deref,
-		O: 'static + Deref,
+		O: 'static + OutputSpender,
 		K: 'static + Deref + Send,
 		OS: 'static + Deref<Target = OutputSweeperSync<T, D, F, CF, K, L, O>> + Send,
 	>(
@@ -1573,7 +1571,6 @@ impl BackgroundProcessor {
 		PM::Target: APeerManager,
 		LM::Target: ALiquidityManagerSync,
 		D::Target: ChangeDestinationSourceSync,
-		O::Target: 'static + OutputSpender,
 		K::Target: 'static + KVStoreSync,
 	{
 		let stop_thread = Arc::new(AtomicBool::new(false));

lightning/src/sign/mod.rs

@@ -1063,6 +1063,23 @@ pub trait OutputSpender {
 	) -> Result<Transaction, ()>;
 }
 
+impl<T: OutputSpender + ?Sized, O: Deref<Target = T>> OutputSpender for O {
+	fn spend_spendable_outputs(
+		&self, descriptors: &[&SpendableOutputDescriptor], outputs: Vec<TxOut>,
+		change_destination_script: ScriptBuf, feerate_sat_per_1000_weight: u32,
+		locktime: Option<LockTime>, secp_ctx: &Secp256k1<All>,
+	) -> Result<Transaction, ()> {
+		self.deref().spend_spendable_outputs(
+			descriptors,
+			outputs,
+			change_destination_script,
+			feerate_sat_per_1000_weight,
+			locktime,
+			secp_ctx,
+		)
+	}
+}
+
 // Primarily needed in doctests because of https://github.com/rust-lang/rust/issues/67295
 /// A dynamic [`SignerProvider`] temporarily needed for doc tests.
 ///

lightning/src/util/sweep.rs

@@ -344,10 +344,9 @@ pub struct OutputSweeper<
 	F: Filter,
 	K: KVStore,
 	L: Logger,
-	O: Deref,
+	O: OutputSpender,
 > where
 	D::Target: ChangeDestinationSource,
-	O::Target: OutputSpender,
 {
 	sweeper_state: Mutex<SweeperState>,
 	pending_sweep: AtomicBool,
@@ -367,11 +366,10 @@ impl<
 		F: Filter,
 		K: KVStore,
 		L: Logger,
-		O: Deref,
+		O: OutputSpender,
 	> OutputSweeper<B, D, E, F, K, L, O>
 where
 	D::Target: ChangeDestinationSource,
-	O::Target: OutputSpender,
 {
 	/// Constructs a new [`OutputSweeper`].
 	///
@@ -721,11 +719,10 @@ impl<
 		F: Filter + Sync + Send,
 		K: KVStore,
 		L: Logger,
-		O: Deref,
+		O: OutputSpender,
 	> Listen for OutputSweeper<B, D, E, F, K, L, O>
 where
 	D::Target: ChangeDestinationSource,
-	O::Target: OutputSpender,
 {
 	fn filtered_block_connected(
 		&self, header: &Header, txdata: &chain::transaction::TransactionData, height: u32,
@@ -764,11 +761,10 @@ impl<
 		F: Filter + Sync + Send,
 		K: KVStore,
 		L: Logger,
-		O: Deref,
+		O: OutputSpender,
 	> Confirm for OutputSweeper<B, D, E, F, K, L, O>
 where
 	D::Target: ChangeDestinationSource,
-	O::Target: OutputSpender,
 {
 	fn transactions_confirmed(
 		&self, header: &Header, txdata: &chain::transaction::TransactionData, height: u32,
@@ -863,11 +859,10 @@ impl<
 		F: Filter + Sync + Send,
 		K: KVStore,
 		L: Logger,
-		O: Deref,
+		O: OutputSpender,
 	> ReadableArgs<(B, E, Option<F>, O, D, K, L)> for (BestBlock, OutputSweeper<B, D, E, F, K, L, O>)
 where
 	D::Target: ChangeDestinationSource,
-	O::Target: OutputSpender,
 {
 	#[inline]
 	fn read<R: io::Read>(
@@ -935,11 +930,10 @@ pub struct OutputSweeperSync<
 	F: Filter,
 	K: Deref,
 	L: Logger,
-	O: Deref,
+	O: OutputSpender,
 > where
 	D::Target: ChangeDestinationSourceSync,
 	K::Target: KVStoreSync,
-	O::Target: OutputSpender,
 {
 	sweeper:
 		OutputSweeper<B, ChangeDestinationSourceSyncWrapper<D>, E, F, KVStoreSyncWrapper<K>, L, O>,
@@ -952,12 +946,11 @@ impl<
 		F: Filter,
 		K: Deref,
 		L: Logger,
-		O: Deref,
+		O: OutputSpender,
 	> OutputSweeperSync<B, D, E, F, K, L, O>
 where
 	D::Target: ChangeDestinationSourceSync,
 	K::Target: KVStoreSync,
-	O::Target: OutputSpender,
 {
 	/// Constructs a new [`OutputSweeperSync`] instance.
 	///
@@ -1075,12 +1068,11 @@ impl<
 		F: Filter + Sync + Send,
 		K: Deref,
 		L: Logger,
-		O: Deref,
+		O: OutputSpender,
 	> Listen for OutputSweeperSync<B, D, E, F, K, L, O>
 where
 	D::Target: ChangeDestinationSourceSync,
 	K::Target: KVStoreSync,
-	O::Target: OutputSpender,
 {
 	fn filtered_block_connected(
 		&self, header: &Header, txdata: &chain::transaction::TransactionData, height: u32,
@@ -1100,12 +1092,11 @@ impl<
 		F: Filter + Sync + Send,
 		K: Deref,
 		L: Logger,
-		O: Deref,
+		O: OutputSpender,
 	> Confirm for OutputSweeperSync<B, D, E, F, K, L, O>
 where
 	D::Target: ChangeDestinationSourceSync,
 	K::Target: KVStoreSync,
-	O::Target: OutputSpender,
 {
 	fn transactions_confirmed(
 		&self, header: &Header, txdata: &chain::transaction::TransactionData, height: u32,
@@ -1133,13 +1124,12 @@ impl<
 		F: Filter + Sync + Send,
 		K: Deref,
 		L: Logger,
-		O: Deref,
+		O: OutputSpender,
 	> ReadableArgs<(B, E, Option<F>, O, D, K, L)>
 	for (BestBlock, OutputSweeperSync<B, D, E, F, K, L, O>)
 where
 	D::Target: ChangeDestinationSourceSync,
 	K::Target: KVStoreSync,
-	O::Target: OutputSpender,
 {
 	#[inline]
 	fn read<R: io::Read>(