Add a ClosureReason::LocallyCoopClosedUnfundedChannel

When a channel is "coop" closed prior to it being funded, it is
closed immediately. Instead of reporting
`ClosureReason::*InitiatedCooperativeClosure` (which would be
somewhat misleading), we report
`ClosureReason::CounterpartyCoopClosedUnfundedCHannel` when our
counterparty does it. However, when we do it, we report
`ClosureReason::HolderForceClosed`, which is highly confusing given
the user did *not* call a force-closure method.

Instead, here, we add a
`ClosureReason::LocallyCoopClosedUnfundedChannel` to match the
`CounterpartyCoopClosedUnfundedCHannel` variant and use it.

Author: TheBlueMatt

lightning/src/events/mod.rs

@@ -383,6 +383,12 @@ pub enum ClosureReason {
 	/// The counterparty requested a cooperative close of a channel that had not been funded yet.
 	/// The channel has been immediately closed.
 	CounterpartyCoopClosedUnfundedChannel,
+	/// We requested a cooperative close of a channel that had not been funded yet.
+	/// The channel has been immediately closed.
+	///
+	/// Note that events containing this variant will be lost on downgrade to a version of LDK
+	/// prior to 0.2.
+	LocallyCoopClosedUnfundedChannel,
 	/// Another channel in the same funding batch closed before the funding transaction
 	/// was ready to be broadcast.
 	FundingBatchClosure,
@@ -454,6 +460,9 @@ impl core::fmt::Display for ClosureReason {
 			ClosureReason::CounterpartyCoopClosedUnfundedChannel => {
 				f.write_str("the peer requested the unfunded channel be closed")
 			},
+			ClosureReason::LocallyCoopClosedUnfundedChannel => {
+				f.write_str("we requested the unfunded channel be closed")
+			},
 			ClosureReason::FundingBatchClosure => {
 				f.write_str("another channel in the same funding batch closed")
 			},
@@ -487,6 +496,7 @@ impl_writeable_tlv_based_enum_upgradable!(ClosureReason,
 		(0, peer_feerate_sat_per_kw, required),
 		(2, required_feerate_sat_per_kw, required),
 	},
+	(25, LocallyCoopClosedUnfundedChannel) => {},
 );
 
 /// The type of HTLC handling performed in [`Event::HTLCHandlingFailed`].

lightning/src/ln/channelmanager.rs

@@ -4126,7 +4126,7 @@ where
 						}
 					} else {
 						let mut shutdown_res = chan_entry.get_mut()
-							.force_shutdown(false, ClosureReason::HolderForceClosed { broadcasted_latest_txn: Some(false) });
+							.force_shutdown(false, ClosureReason::LocallyCoopClosedUnfundedChannel);
 						remove_channel_entry!(self, peer_state, chan_entry, shutdown_res);
 						shutdown_result = Some(shutdown_res);
 					}

lightning/src/ln/shutdown_tests.rs

@@ -337,7 +337,7 @@ fn close_on_unfunded_channel() {
 	let _open_chan = get_event_msg!(nodes[0], MessageSendEvent::SendOpenChannel, node_b_id);
 
 	nodes[0].node.close_channel(&chan_id, &node_b_id).unwrap();
-	let reason = ClosureReason::HolderForceClosed { broadcasted_latest_txn: Some(false) };
+	let reason = ClosureReason::LocallyCoopClosedUnfundedChannel;
 	check_closed_event!(nodes[0], 1, reason, [node_b_id], 1_000_000);
 }