f - associated type on SignFunction

jkczyz · jkczyz · commit 0adcda547b0f · 2024-03-05T15:53:29.000-06:00
diff --git a/lightning/src/offers/invoice.rs b/lightning/src/offers/invoice.rs
@@ -58,9 +58,9 @@
 //!     .allow_mpp()
 //!     .fallback_v0_p2wpkh(&wpubkey_hash)
 //!     .build()?
-//!     .sign::<_, Infallible>(|message: &UnsignedBolt12Invoice|
+//!     .sign(|message: &UnsignedBolt12Invoice| -> Result<_, Infallible> {
 //!         Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
-//!     )
+//!     })
 //!     .expect("failed verifying signature")
 //!     .write(&mut buffer)
 //!     .unwrap();
@@ -91,9 +91,9 @@
 //!     .allow_mpp()
 //!     .fallback_v0_p2wpkh(&wpubkey_hash)
 //!     .build()?
-//!     .sign::<_, Infallible>(|message: &UnsignedBolt12Invoice|
+//!     .sign(|message: &UnsignedBolt12Invoice| -> Result<_, Infallible> {
 //!         Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
-//!     )
+//!     })
 //!     .expect("failed verifying signature")
 //!     .write(&mut buffer)
 //!     .unwrap();
@@ -321,9 +321,9 @@ macro_rules! invoice_derived_signing_pubkey_builder_methods { ($self: ident, $se
 		let mut unsigned_invoice = UnsignedBolt12Invoice::new(invreq_bytes, invoice.clone());
 
 		let invoice = unsigned_invoice
-			.sign::<_, Infallible>(|message: &UnsignedBolt12Invoice|
+			.sign(|message: &UnsignedBolt12Invoice| -> Result<_, Infallible> {
 				Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
-			)
+			})
 			.unwrap();
 		Ok(invoice)
 	}
@@ -529,9 +529,11 @@ macro_rules! unsigned_invoice_sign_method { ($self: ident, $self_type: ty $(, $s
 	/// Signs the [`TaggedHash`] of the invoice using the given function.
 	///
 	/// Note: The hash computation may have included unknown, odd TLV records.
-	pub fn sign<F, E>($($self_mut)* $self: $self_type, sign: F) -> Result<Bolt12Invoice, SignError<E>>
+	pub fn sign<F>(
+		$($self_mut)* $self: $self_type, sign: F
+	) -> Result<Bolt12Invoice, SignError<F::Error>>
 	where
-		F: SignFunction<Self, E>,
+		F: SignFunction<Self>,
 	{
 		let pubkey = $self.contents.fields().signing_pubkey;
 		let signature = merkle::sign_message(sign, &$self, pubkey)?;
diff --git a/lightning/src/offers/invoice_request.rs b/lightning/src/offers/invoice_request.rs
@@ -48,9 +48,9 @@
 //!     .quantity(5)?
 //!     .payer_note("foo".to_string())
 //!     .build()?
-//!     .sign::<_, Infallible>(|message: &UnsignedInvoiceRequest|
+//!     .sign(|message: &UnsignedInvoiceRequest| -> Result<_, Infallible> {
 //!         Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
-//!     )
+//!     })
 //!     .expect("failed verifying signature")
 //!     .write(&mut buffer)
 //!     .unwrap();
@@ -225,9 +225,9 @@ macro_rules! invoice_request_derived_payer_id_builder_methods { (
 		let secp_ctx = secp_ctx.unwrap();
 		let keys = keys.unwrap();
 		let invoice_request = unsigned_invoice_request
-			.sign::<_, Infallible>(|message: &UnsignedInvoiceRequest|
+			.sign(|message: &UnsignedInvoiceRequest| -> Result<_, Infallible> {
 				Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
-			)
+			})
 			.unwrap();
 		Ok(invoice_request)
 	}
@@ -514,9 +514,11 @@ macro_rules! unsigned_invoice_request_sign_method { (
 	/// Signs the [`TaggedHash`] of the invoice request using the given function.
 	///
 	/// Note: The hash computation may have included unknown, odd TLV records.
-	pub fn sign<F, E>($($self_mut)* $self: $self_type, sign: F) -> Result<InvoiceRequest, SignError<E>>
+	pub fn sign<F>(
+		$($self_mut)* $self: $self_type, sign: F
+	) -> Result<InvoiceRequest, SignError<F::Error>>
 	where
-		F: SignFunction<Self, E>,
+		F: SignFunction<Self>,
 	{
 		let pubkey = $self.contents.payer_id;
 		let signature = merkle::sign_message(sign, &$self, pubkey)?;
@@ -2116,9 +2118,9 @@ mod tests {
 			.build().unwrap()
 			.request_invoice(vec![1; 32], keys.public_key()).unwrap()
 			.build().unwrap()
-			.sign::<_, Infallible>(|message: &UnsignedInvoiceRequest|
+			.sign(|message: &UnsignedInvoiceRequest| -> Result<_, Infallible> {
 				Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &keys))
-			)
+			})
 			.unwrap();
 
 		let mut encoded_invoice_request = Vec::new();
diff --git a/lightning/src/offers/merkle.rs b/lightning/src/offers/merkle.rs
@@ -76,24 +76,29 @@ impl AsRef<TaggedHash> for TaggedHash {
 
 /// Error when signing messages.
 #[derive(Debug, PartialEq)]
-pub enum SignError<E> {
+pub enum SignError<E = ()> {
 	/// User-defined error when signing the message.
 	Signing(E),
 	/// Error when verifying the produced signature using the given pubkey.
 	Verification(secp256k1::Error),
 }
 
 /// A function for signing a [`TaggedHash`].
-pub trait SignFunction<T: AsRef<TaggedHash>, E> {
+pub trait SignFunction<T: AsRef<TaggedHash>> {
+	/// Error type returned by the function.
+	type Error;
+
 	/// Signs a [`TaggedHash`] computed over the merkle root of `message`'s TLV stream.
-	fn sign(&self, message: &T) -> Result<Signature, E>;
+	fn sign(&self, message: &T) -> Result<Signature, Self::Error>;
 }
 
-impl<F, T, E> SignFunction<T, E> for F
+impl<F, T, E> SignFunction<T> for F
 where
 	F: Fn(&T) -> Result<Signature, E>,
 	T: AsRef<TaggedHash>,
 {
+	type Error = E;
+
 	fn sign(&self, message: &T) -> Result<Signature, E> {
 		self(message)
 	}
@@ -112,7 +117,7 @@ pub(super) fn sign_message<F, T, E>(
 	f: F, message: &T, pubkey: PublicKey,
 ) -> Result<Signature, SignError<E>>
 where
-	F: SignFunction<T, E>,
+	F: SignFunction<T, Error = E>,
 	T: AsRef<TaggedHash>,
 {
 	let signature = f.sign(message).map_err(|e| SignError::Signing(e))?;
@@ -337,9 +342,9 @@ mod tests {
 			.build_unchecked()
 			.request_invoice(vec![0; 8], payer_keys.public_key()).unwrap()
 			.build_unchecked()
-			.sign::<_, Infallible>(|message: &UnsignedInvoiceRequest|
+			.sign(|message: &UnsignedInvoiceRequest| -> Result<_, Infallible> {
 				Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &payer_keys))
-			)
+			})
 			.unwrap();
 		assert_eq!(
 			invoice_request.to_string(),
@@ -391,9 +396,9 @@ mod tests {
 			.build_unchecked()
 			.request_invoice(vec![0; 8], payer_keys.public_key()).unwrap()
 			.build_unchecked()
-			.sign::<_, Infallible>(|message: &UnsignedInvoiceRequest|
+			.sign(|message: &UnsignedInvoiceRequest| -> Result<_, Infallible> {
 				Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &payer_keys))
-			)
+			})
 			.unwrap();
 
 		let mut bytes_without_signature = Vec::new();
@@ -423,9 +428,9 @@ mod tests {
 			.build_unchecked()
 			.request_invoice(vec![0; 8], payer_keys.public_key()).unwrap()
 			.build_unchecked()
-			.sign::<_, Infallible>(|message: &UnsignedInvoiceRequest|
+			.sign(|message: &UnsignedInvoiceRequest| -> Result<_, Infallible> {
 				Ok(secp_ctx.sign_schnorr_no_aux_rand(message.as_ref().as_digest(), &payer_keys))
-			)
+			})
 			.unwrap();
 
 		let tlv_stream = TlvStream::new(&invoice_request.bytes).range(0..1)
