Make payment_path_failed path type bindings-mappable

The bindings don't currently support passing `Vec`s of objects
which it mappes as "opaque types". This is because it will require
clones to convert its own list of references to Rust's list of
objects.

In the near future we should resolve this limitation, allowing us
to revert this (and make `find_route`'s method signature similarly
cleaner), but for now we must avoid `Vec<OpaqueType>`.

Author: TheBlueMatt

lightning-invoice/src/payment.rs

@@ -71,7 +71,7 @@
 //! #     fn channel_penalty_msat(
 //! #         &self, _short_channel_id: u64, _source: &NodeId, _target: &NodeId
 //! #     ) -> u64 { 0 }
-//! #     fn payment_path_failed(&mut self, _path: &Vec<RouteHop>, _short_channel_id: u64) {}
+//! #     fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
 //! # }
 //! #
 //! # struct FakeLogger {};
@@ -415,7 +415,8 @@ where
 				all_paths_failed, payment_id, payment_hash, rejected_by_dest, path, short_channel_id, retry, ..
 			} => {
 				if let Some(short_channel_id) = short_channel_id {
-					self.scorer.lock().payment_path_failed(path, *short_channel_id);
+					let t = path.iter().collect::<Vec<_>>();
+					self.scorer.lock().payment_path_failed(&t, *short_channel_id);
 				}
 
 				if *rejected_by_dest {
@@ -1099,7 +1100,7 @@ mod tests {
 			&self, _short_channel_id: u64, _source: &NodeId, _target: &NodeId
 		) -> u64 { 0 }
 
-		fn payment_path_failed(&mut self, _path: &Vec<RouteHop>, short_channel_id: u64) {
+		fn payment_path_failed(&mut self, _path: &[&RouteHop], short_channel_id: u64) {
 			if let Some(expected_short_channel_id) = self.expectations.pop_front() {
 				assert_eq!(short_channel_id, expected_short_channel_id);
 			}

lightning/src/routing/mod.rs

@@ -30,7 +30,7 @@ pub trait Score {
 	fn channel_penalty_msat(&self, short_channel_id: u64, source: &NodeId, target: &NodeId) -> u64;
 
 	/// Handles updating channel penalties after failing to route through a channel.
-	fn payment_path_failed(&mut self, path: &Vec<RouteHop>, short_channel_id: u64);
+	fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64);
 }
 
 /// A scorer that is accessed under a lock.
@@ -70,7 +70,7 @@ impl<S: Score, T: DerefMut<Target=S>> Score for T {
 		self.deref().channel_penalty_msat(short_channel_id, source, target)
 	}
 
-	fn payment_path_failed(&mut self, path: &Vec<RouteHop>, short_channel_id: u64) {
+	fn payment_path_failed(&mut self, path: &[&RouteHop], short_channel_id: u64) {
 		self.deref_mut().payment_path_failed(path, short_channel_id)
 	}
 }

lightning/src/routing/router.rs

@@ -4553,7 +4553,7 @@ mod tests {
 			if short_channel_id == self.short_channel_id { u64::max_value() } else { 0 }
 		}
 
-		fn payment_path_failed(&mut self, _path: &Vec<RouteHop>, _short_channel_id: u64) {}
+		fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
 	}
 
 	struct BadNodeScorer {
@@ -4565,7 +4565,7 @@ mod tests {
 			if *target == self.node_id { u64::max_value() } else { 0 }
 		}
 
-		fn payment_path_failed(&mut self, _path: &Vec<RouteHop>, _short_channel_id: u64) {}
+		fn payment_path_failed(&mut self, _path: &[&RouteHop], _short_channel_id: u64) {}
 	}
 
 	#[test]

lightning/src/routing/scorer.rs

@@ -149,7 +149,7 @@ impl routing::Score for Scorer {
 		self.params.base_penalty_msat + failure_penalty_msat
 	}
 
-	fn payment_path_failed(&mut self, _path: &Vec<RouteHop>, short_channel_id: u64) {
+	fn payment_path_failed(&mut self, _path: &[&RouteHop], short_channel_id: u64) {
 		let failure_penalty_msat = self.params.failure_penalty_msat;
 		#[cfg(not(feature = "no-std"))]
 		{