Make impl_writeable_tlv_based_enum* actually upgradable

In cc78b77 it was discovered that
`impl_writeable_tlv_based_enum_upgradable` wasn't actually
upgradable - tuple variants weren't written with length-prefixes,
causing downgrades with new tuple variants to be unreadable by
older clients as they wouldn't know where to stop reading.

This was fixed by simply assuming that any new variants will be
non-tuple variants with a length prefix, but no code write-side
changes were made, allowing new code to freely continue to use the
broken tuple-variant serialization.

Here we address this be defining yet more serialization macros
which aren't broken, and convert existing usage of the existing
macros using non-length-prefixed tuple variants to renamed
`*_legacy` macros.

Note that this changes the serialization format of
`impl_writeable_tlv_based_enum[_upgradable]` when tuple fields are
written, and as such deliberately changes the call semantics for
such tuples.

Only the serialization format of `MessageContext` is changed here
which is fine as it has not yet reached a release of LDK.

Author: TheBlueMatt

lightning/src/blinded_path/message.rs

@@ -119,17 +119,17 @@ pub enum OffersContext {
 	},
 }
 
-impl_writeable_tlv_based_enum!(MessageContext, ;
-	(0, Offers),
-	(1, Custom),
+impl_writeable_tlv_based_enum!(MessageContext,
+	{0, Offers} => (),
+	{1, Custom} => (),
 );
 
 impl_writeable_tlv_based_enum!(OffersContext,
 	(0, Unknown) => {},
 	(1, OutboundPayment) => {
 		(0, payment_id, required),
 	},
-;);
+);
 
 /// Construct blinded onion message hops for the given `intermediate_nodes` and `recipient_node_id`.
 pub(super) fn blinded_hops<T: secp256k1::Signing + secp256k1::Verification>(

lightning/src/blinded_path/payment.rs

@@ -431,7 +431,7 @@ impl Readable for PaymentConstraints {
 	}
 }
 
-impl_writeable_tlv_based_enum!(PaymentContext,
+impl_writeable_tlv_based_enum_legacy!(PaymentContext,
 	;
 	(0, Unknown),
 	(1, Bolt12Offer),

lightning/src/chain/channelmonitor.rs

@@ -189,7 +189,7 @@ pub enum MonitorEvent {
 		monitor_update_id: u64,
 	},
 }
-impl_writeable_tlv_based_enum_upgradable!(MonitorEvent,
+impl_writeable_tlv_based_enum_upgradable_legacy!(MonitorEvent,
 	// Note that Completed is currently never serialized to disk as it is generated only in
 	// ChainMonitor.
 	(0, Completed) => {

lightning/src/chain/package.rs

@@ -689,7 +689,7 @@ impl PackageSolvingData {
 	}
 }
 
-impl_writeable_tlv_based_enum!(PackageSolvingData, ;
+impl_writeable_tlv_based_enum_legacy!(PackageSolvingData, ;
 	(0, RevokedOutput),
 	(1, RevokedHTLCOutput),
 	(2, CounterpartyOfferedHTLCOutput),

lightning/src/events/mod.rs

@@ -171,7 +171,7 @@ impl PaymentPurpose {
 	}
 }
 
-impl_writeable_tlv_based_enum!(PaymentPurpose,
+impl_writeable_tlv_based_enum_legacy!(PaymentPurpose,
 	(0, Bolt11InvoicePayment) => {
 		(0, payment_preimage, option),
 		(2, payment_secret, required),
@@ -494,7 +494,7 @@ enum InterceptNextHop {
 impl_writeable_tlv_based_enum!(InterceptNextHop,
 	(0, FakeScid) => {
 		(0, requested_next_hop_scid, required),
-	};
+	},
 );
 
 /// The reason the payment failed. Used in [`Event::PaymentFailed`].
@@ -535,7 +535,7 @@ impl_writeable_tlv_based_enum!(PaymentFailureReason,
 	(4, RetriesExhausted) => {},
 	(6, PaymentExpired) => {},
 	(8, RouteNotFound) => {},
-	(10, UnexpectedError) => {}, ;
+	(10, UnexpectedError) => {},
 );
 
 /// An Event which you should probably take some action in response to.

lightning/src/ln/channel.rs

@@ -130,7 +130,7 @@ impl_writeable_tlv_based_enum!(InboundHTLCResolution,
 	},
 	(2, Pending) => {
 		(0, update_add_htlc, required),
-	};
+	},
 );
 
 enum InboundHTLCState {
@@ -8390,7 +8390,7 @@ fn get_initial_channel_type(config: &UserConfig, their_features: &InitFeatures)
 const SERIALIZATION_VERSION: u8 = 4;
 const MIN_SERIALIZATION_VERSION: u8 = 3;
 
-impl_writeable_tlv_based_enum!(InboundHTLCRemovalReason,;
+impl_writeable_tlv_based_enum_legacy!(InboundHTLCRemovalReason,;
 	(0, FailRelay),
 	(1, FailMalformed),
 	(2, Fulfill),

lightning/src/ln/channel_state.rs

@@ -69,7 +69,7 @@ impl_writeable_tlv_based_enum_upgradable!(InboundHTLCStateDetails,
 	(0, AwaitingRemoteRevokeToAdd) => {},
 	(2, Committed) => {},
 	(4, AwaitingRemoteRevokeToRemoveFulfill) => {},
-	(6, AwaitingRemoteRevokeToRemoveFail) => {};
+	(6, AwaitingRemoteRevokeToRemoveFail) => {},
 );
 
 /// Exposes details around pending inbound HTLCs.
@@ -159,7 +159,7 @@ impl_writeable_tlv_based_enum_upgradable!(OutboundHTLCStateDetails,
 	(0, AwaitingRemoteRevokeToAdd) => {},
 	(2, Committed) => {},
 	(4, AwaitingRemoteRevokeToRemoveSuccess) => {},
-	(6, AwaitingRemoteRevokeToRemoveFailure) => {};
+	(6, AwaitingRemoteRevokeToRemoveFailure) => {},
 );
 
 /// Exposes details around pending outbound HTLCs.
@@ -701,5 +701,5 @@ impl_writeable_tlv_based_enum!(ChannelShutdownState,
 	(2, ShutdownInitiated) => {},
 	(4, ResolvingHTLCs) => {},
 	(6, NegotiatingClosingFee) => {},
-	(8, ShutdownComplete) => {}, ;
+	(8, ShutdownComplete) => {},
 );

lightning/src/ln/channelmanager.rs

@@ -476,7 +476,7 @@ impl_writeable_tlv_based_enum!(SentHTLCId,
 	},
 	(2, OutboundRoute) => {
 		(0, session_priv, required),
-	};
+	},
 );
 
 
@@ -881,7 +881,7 @@ impl_writeable_tlv_based_enum!(EventCompletionAction,
 		// Note that by the time we get past the required read above, channel_funding_outpoint will be
 		// filled in, so we can safely unwrap it here.
 		(3, channel_id, (default_value, ChannelId::v1_from_funding_outpoint(channel_funding_outpoint.0.unwrap()))),
-	};
+	}
 );
 
 #[derive(Debug)]
@@ -10808,7 +10808,7 @@ impl_writeable_tlv_based_enum!(PendingHTLCRouting,
 		(4, payment_data, option), // Added in 0.0.116
 		(5, custom_tlvs, optional_vec),
 	},
-;);
+);
 
 impl_writeable_tlv_based!(PendingHTLCInfo, {
 	(0, routing, required),
@@ -10888,14 +10888,14 @@ impl Readable for HTLCFailureMsg {
 	}
 }
 
-impl_writeable_tlv_based_enum!(PendingHTLCStatus, ;
+impl_writeable_tlv_based_enum_legacy!(PendingHTLCStatus, ;
 	(0, Forward),
 	(1, Fail),
 );
 
 impl_writeable_tlv_based_enum!(BlindedFailure,
 	(0, FromIntroductionNode) => {},
-	(2, FromBlindedNode) => {}, ;
+	(2, FromBlindedNode) => {},
 );
 
 impl_writeable_tlv_based!(HTLCPreviousHopData, {

lightning/src/ln/onion_utils.rs

@@ -953,7 +953,7 @@ impl_writeable_tlv_based_enum!(HTLCFailReasonRepr,
 		(0, failure_code, required),
 		(2, data, required_vec),
 	},
-;);
+);
 
 impl HTLCFailReason {
 	#[rustfmt::skip]

lightning/src/ln/outbound_payment.rs

@@ -300,13 +300,13 @@ pub enum Retry {
 }
 
 #[cfg(not(feature = "std"))]
-impl_writeable_tlv_based_enum!(Retry,
+impl_writeable_tlv_based_enum_legacy!(Retry,
 	;
 	(0, Attempts)
 );
 
 #[cfg(feature = "std")]
-impl_writeable_tlv_based_enum!(Retry,
+impl_writeable_tlv_based_enum_legacy!(Retry,
 	;
 	(0, Attempts),
 	(2, Timeout)
@@ -397,7 +397,7 @@ pub(crate) enum StaleExpiration {
 	AbsoluteTimeout(core::time::Duration),
 }
 
-impl_writeable_tlv_based_enum!(StaleExpiration,
+impl_writeable_tlv_based_enum_legacy!(StaleExpiration,
 	;
 	(0, TimerTicks),
 	(2, AbsoluteTimeout)