Enable option_simple_close feature by default

.. although behind a `cfg` gate for now

Author: tnull

Cargo.toml

@@ -67,4 +67,5 @@ check-cfg = [
     "cfg(require_route_graph_test)",
     "cfg(splicing)",
     "cfg(async_payments)",
+    "cfg(simple_close)",
 ]

ci/ci-tests.sh

@@ -155,4 +155,6 @@ RUSTFLAGS="--cfg=splicing" cargo test --verbose --color always -p lightning
 [ "$CI_MINIMIZE_DISK_USAGE" != "" ] && cargo clean
 RUSTFLAGS="--cfg=async_payments" cargo test --verbose --color always -p lightning
 [ "$CI_MINIMIZE_DISK_USAGE" != "" ] && cargo clean
+RUSTFLAGS="--cfg=simple_close" cargo test --verbose --color always -p lightning
+[ "$CI_MINIMIZE_DISK_USAGE" != "" ] && cargo clean
 RUSTFLAGS="--cfg=lsps1_service" cargo test --verbose --color always -p lightning-liquidity

lightning/src/ln/channelmanager.rs

@@ -13379,7 +13379,7 @@ pub(crate) fn provided_channel_type_features(config: &UserConfig) -> ChannelType
 /// [`ChannelManager`].
 pub fn provided_init_features(config: &UserConfig) -> InitFeatures {
 	// Note that if new features are added here which other peers may (eventually) require, we
-	// should also add the corresponding (optional) bit to the [`ChannelMessageHandler`] impl for
+	// should also add the corresponding (optional) bit to the [`BaseMessageHandler`] impl for
 	// [`ErroringMessageHandler`].
 	let mut features = InitFeatures::empty();
 	features.set_data_loss_protect_required();
@@ -13395,6 +13395,8 @@ pub fn provided_init_features(config: &UserConfig) -> InitFeatures {
 	features.set_zero_conf_optional();
 	features.set_route_blinding_optional();
 	features.set_provide_storage_optional();
+	#[cfg(simple_close)]
+	features.set_simple_close_optional();
 	if config.channel_handshake_config.negotiate_anchors_zero_fee_htlc_tx {
 		features.set_anchors_zero_fee_htlc_tx_optional();
 	}

lightning/src/ln/peer_handler.rs

@@ -271,6 +271,8 @@ impl BaseMessageHandler for ErroringMessageHandler {
 		features.set_scid_privacy_optional();
 		features.set_zero_conf_optional();
 		features.set_route_blinding_optional();
+		#[cfg(simple_close)]
+		features.set_simple_close_optional();
 		features
 	}