Add optional lifetime to tlv_stream macro

Using the tlv_stream macro without a type needing a reference results in
a compilation error because of an unused lifetime parameter. To avoid
this, add an optional lifetime parameter to the macro. This allows for
experimental TLVs, which will be empty initially, and TLVs of entirely
primitive types.

Author: jkczyz

lightning/src/offers/invoice.rs

@@ -1237,7 +1237,7 @@ impl TryFrom<Vec<u8>> for Bolt12Invoice {
 /// Valid type range for invoice TLV records.
 pub(super) const INVOICE_TYPES: core::ops::Range<u64> = 160..240;
 
-tlv_stream!(InvoiceTlvStream, InvoiceTlvStreamRef, INVOICE_TYPES, {
+tlv_stream!(InvoiceTlvStream, InvoiceTlvStreamRef<'a>, INVOICE_TYPES, {
 	(160, paths: (Vec<BlindedPath>, WithoutLength, Iterable<'a, BlindedPathIter<'a>, BlindedPath>)),
 	(162, blindedpay: (Vec<BlindedPayInfo>, WithoutLength, Iterable<'a, BlindedPayInfoIter<'a>, BlindedPayInfo>)),
 	(164, created_at: (u64, HighZeroBytesDroppedBigSize)),

lightning/src/offers/invoice_request.rs

@@ -1061,7 +1061,7 @@ pub(super) const INVOICE_REQUEST_PAYER_ID_TYPE: u64 = 88;
 
 // This TLV stream is used for both InvoiceRequest and Refund, but not all TLV records are valid for
 // InvoiceRequest as noted below.
-tlv_stream!(InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef, INVOICE_REQUEST_TYPES, {
+tlv_stream!(InvoiceRequestTlvStream, InvoiceRequestTlvStreamRef<'a>, INVOICE_REQUEST_TYPES, {
 	(80, chain: ChainHash),
 	(82, amount: (u64, HighZeroBytesDroppedBigSize)),
 	(84, features: (InvoiceRequestFeatures, WithoutLength)),

lightning/src/offers/merkle.rs

@@ -21,7 +21,7 @@ use crate::prelude::*;
 /// Valid type range for signature TLV records.
 const SIGNATURE_TYPES: core::ops::RangeInclusive<u64> = 240..=1000;
 
-tlv_stream!(SignatureTlvStream, SignatureTlvStreamRef, SIGNATURE_TYPES, {
+tlv_stream!(SignatureTlvStream, SignatureTlvStreamRef<'a>, SIGNATURE_TYPES, {
 	(240, signature: Signature),
 });
 

lightning/src/offers/offer.rs

@@ -1077,7 +1077,7 @@ const OFFER_METADATA_TYPE: u64 = 4;
 /// TLV record type for [`Offer::issuer_signing_pubkey`].
 const OFFER_ISSUER_ID_TYPE: u64 = 22;
 
-tlv_stream!(OfferTlvStream, OfferTlvStreamRef, OFFER_TYPES, {
+tlv_stream!(OfferTlvStream, OfferTlvStreamRef<'a>, OFFER_TYPES, {
 	(2, chains: (Vec<ChainHash>, WithoutLength)),
 	(OFFER_METADATA_TYPE, metadata: (Vec<u8>, WithoutLength)),
 	(6, currency: CurrencyCode),

lightning/src/offers/payer.rs

@@ -30,6 +30,6 @@ pub(super) struct PayerContents(pub Metadata);
 /// [`Refund::payer_metadata`]: crate::offers::refund::Refund::payer_metadata
 pub(super) const PAYER_METADATA_TYPE: u64 = 0;
 
-tlv_stream!(PayerTlvStream, PayerTlvStreamRef, 0..1, {
+tlv_stream!(PayerTlvStream, PayerTlvStreamRef<'a>, 0..1, {
 	(PAYER_METADATA_TYPE, metadata: (Vec<u8>, WithoutLength)),
 });

lightning/src/util/ser_macros.rs

@@ -952,7 +952,7 @@ macro_rules! impl_writeable_tlv_based {
 /// [`Readable`]: crate::util::ser::Readable
 /// [`Writeable`]: crate::util::ser::Writeable
 macro_rules! tlv_stream {
-	($name:ident, $nameref:ident, $range:expr, {
+	($name:ident, $nameref:ident $(<$lifetime:lifetime>)?, $range:expr, {
 		$(($type:expr, $field:ident : $fieldty:tt)),* $(,)*
 	}) => {
 		#[derive(Debug)]
@@ -964,13 +964,13 @@ macro_rules! tlv_stream {
 
 		#[cfg_attr(test, derive(PartialEq))]
 		#[derive(Debug)]
-		pub(crate) struct $nameref<'a> {
+		pub(crate) struct $nameref<$($lifetime)*> {
 			$(
 				pub(super) $field: Option<tlv_record_ref_type!($fieldty)>,
 			)*
 		}
 
-		impl<'a> $crate::util::ser::Writeable for $nameref<'a> {
+		impl<$($lifetime)*> $crate::util::ser::Writeable for $nameref<$($lifetime)*> {
 			fn write<W: $crate::util::ser::Writer>(&self, writer: &mut W) -> Result<(), $crate::io::Error> {
 				encode_tlv_stream!(writer, {
 					$(($type, self.$field, (option, encoding: $fieldty))),*