Remove custom derive_channel_signer methods

The custom derive_channel_signer methods on AnchorDescriptor and
HTLCDescriptor simply delegate to the passed SignerProvider now that
providing ChannelTransactionParameters is no longer needed. Drop these
methods and replace them with the method bodies at the call sites.

Author: jkczyz

lightning/src/events/bump_transaction.rs

@@ -91,14 +91,6 @@ impl AnchorDescriptor {
 		let channel_params = self.channel_derivation_parameters.transaction_parameters.as_holder_broadcastable();
 		chan_utils::build_anchor_input_witness(&channel_params.broadcaster_pubkeys().funding_pubkey, signature)
 	}
-
-	/// Derives the channel signer required to sign the anchor input.
-	pub fn derive_channel_signer<S: EcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
-	where
-		SP::Target: SignerProvider<EcdsaSigner= S>
-	{
-		signer_provider.derive_channel_signer(self.channel_derivation_parameters.keys_id)
-	}
 }
 
 /// Represents the different types of transactions, originating from LDK, to be bumped.
@@ -684,7 +676,7 @@ where
 			log_debug!(self.logger, "Signing anchor transaction {}", anchor_txid);
 			anchor_tx = self.utxo_source.sign_psbt(anchor_psbt)?;
 
-			let signer = anchor_descriptor.derive_channel_signer(&self.signer_provider);
+			let signer = self.signer_provider.derive_channel_signer(anchor_descriptor.channel_derivation_parameters.keys_id);
 			let channel_parameters = &anchor_descriptor.channel_derivation_parameters.transaction_parameters;
 			let anchor_sig = signer.sign_holder_anchor_input(channel_parameters, &anchor_tx, 0, &self.secp)?;
 			anchor_tx.input[0].witness = anchor_descriptor.tx_input_witness(&anchor_sig);
@@ -787,8 +779,9 @@ where
 
 		let mut signers = BTreeMap::new();
 		for (idx, htlc_descriptor) in htlc_descriptors.iter().enumerate() {
-			let signer = signers.entry(htlc_descriptor.channel_derivation_parameters.keys_id)
-				.or_insert_with(|| htlc_descriptor.derive_channel_signer(&self.signer_provider));
+			let keys_id = htlc_descriptor.channel_derivation_parameters.keys_id;
+			let signer = signers.entry(keys_id)
+				.or_insert_with(|| self.signer_provider.derive_channel_signer(keys_id));
 			let htlc_sig = signer.sign_holder_htlc_transaction(&htlc_tx, idx, htlc_descriptor, &self.secp)?;
 			let witness_script = htlc_descriptor.witness_script(&self.secp);
 			htlc_tx.input[idx].witness = htlc_descriptor.tx_input_witness(&htlc_sig, &witness_script);

lightning/src/sign/mod.rs

@@ -68,7 +68,6 @@ use crate::sign::ecdsa::EcdsaChannelSigner;
 use crate::sign::taproot::TaprootChannelSigner;
 use crate::util::atomic_counter::AtomicCounter;
 use core::convert::TryInto;
-use core::ops::Deref;
 use core::sync::atomic::{AtomicUsize, Ordering};
 #[cfg(taproot)]
 use musig2::types::{PartialSignature, PublicNonce};
@@ -703,14 +702,6 @@ impl HTLCDescriptor {
 			&self.channel_derivation_parameters.transaction_parameters.channel_type_features,
 		)
 	}
-
-	/// Derives the channel signer required to sign the HTLC input.
-	pub fn derive_channel_signer<S: EcdsaChannelSigner, SP: Deref>(&self, signer_provider: &SP) -> S
-	where
-		SP::Target: SignerProvider<EcdsaSigner = S>,
-	{
-		signer_provider.derive_channel_signer(self.channel_derivation_parameters.keys_id)
-	}
 }
 
 /// A trait to handle Lightning channel key material without concretizing the channel type or