f use a common macro for building

Author: TheBlueMatt

lightning-macros/src/lib.rs

@@ -277,7 +277,7 @@ pub fn drop_legacy_field_definition(expr: TokenStream) -> TokenStream {
 	for field in new_fields {
 		if let syn::Expr::Macro(syn::ExprMacro { mac, .. }) = &field.expr {
 			let macro_name = mac.path.segments.last().unwrap().ident.to_string();
-			let is_init = macro_name == "_init_tlv_based_struct_field";
+			let is_init = macro_name == "_ignore_arg";
 			let ty_tokens = mac.tokens.clone().into_iter().skip(2).next();
 			if let Some(proc_macro2::TokenTree::Group(group)) = ty_tokens {
 				let first_token = group.stream().into_iter().next();

lightning/src/util/ser_macros.rs

@@ -569,6 +569,13 @@ macro_rules! decode_tlv_stream_with_custom_tlv_decode {
 #[macro_export]
 macro_rules! _decode_tlv_stream_range {
 	($stream: expr, $range: expr, $rewind: ident, {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}
+	 $(, $decode_custom_tlv: expr)?) => { {
+		$crate::_decode_tlv_stream_range!(SKIP_LEGACY, $stream, $range, $rewind, {$(($type, $field, $fieldty)),*} $(, $decode_custom_tlv)?);
+		$({
+			$crate::_run_legacy_tlv_read_logic!($field, $fieldty);
+		})*
+	} };
+	(SKIP_LEGACY, $stream: expr, $range: expr, $rewind: ident, {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}
 	 $(, $decode_custom_tlv: expr)?) => { {
 		use $crate::ln::msgs::DecodeError;
 		let mut last_seen_type: Option<u64> = None;
@@ -648,9 +655,6 @@ macro_rules! _decode_tlv_stream_range {
 		$({
 			$crate::_check_missing_tlv!(last_seen_type, $type, $field, $fieldty);
 		})*
-		$({
-			$crate::_run_legacy_tlv_read_logic!($field, $fieldty);
-		})*
 	} }
 }
 
@@ -914,13 +918,51 @@ macro_rules! _init_and_read_tlv_stream {
 		$(
 			$crate::_init_tlv_field_var!($field, $fieldty);
 		)*
-
 		$crate::decode_tlv_stream!($reader, {
 			$(($type, $field, $fieldty)),*
 		});
 	}
 }
 
+/// Dummy macro that drops the second argument. Used by
+/// [`lightning_macros::drop_legacy_field_definition`] to match for legacy fields.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _ignore_arg {
+	($field: ident, $fieldty: tt) => {
+		$field
+	};
+}
+
+/// Reads a TLV stream with the given fields to build a struct/enum of type `$thing`
+#[doc(hidden)]
+#[macro_export]
+macro_rules! _decode_and_build {
+	($stream: ident, $thing: path, {$(($type: expr, $field: ident, $fieldty: tt)),* $(,)*}) => { {
+		$(
+			$crate::_init_tlv_field_var!($field, $fieldty);
+		)*
+		let tlv_len: $crate::util::ser::BigSize = $crate::util::ser::Readable::read($stream)?;
+		let mut rd = $crate::util::ser::FixedLengthReader::new($stream, tlv_len.0);
+		let rewind = |_, _| { unreachable!() };
+		$crate::_decode_tlv_stream_range!(SKIP_LEGACY, &mut rd, .., rewind, {$(($type, $field, $fieldty)),*});
+		rd.eat_remaining().map_err(|_| $crate::ln::msgs::DecodeError::ShortRead)?;
+		// We mark fields as `mut` as we read them so that legacy post-read actions can modify them
+		// if desired.
+		$(
+			#[allow(unused_mut)]
+			let mut $field = $crate::_init_tlv_based_struct_field!($field, $fieldty);
+		)*
+		$({
+			$crate::_run_legacy_tlv_read_logic!($field, $fieldty);
+		})*
+
+		::lightning_macros::drop_legacy_field_definition!($thing {
+			$($field: $crate::_ignore_arg!($field, $fieldty)),*
+		})
+	} }
+}
+
 /// Implements [`Readable`]/[`Writeable`] for a struct storing it as a set of TLVs
 /// If `$fieldty` is `required`, then `$field` is a required field that is not an [`Option`] nor a [`Vec`].
 /// If `$fieldty` is `(default_value, $default)`, then `$field` will be set to `$default` if not present.
@@ -983,14 +1025,7 @@ macro_rules! impl_writeable_tlv_based {
 
 		impl $crate::util::ser::Readable for $st {
 			fn read<R: $crate::io::Read>(reader: &mut R) -> Result<Self, $crate::ln::msgs::DecodeError> {
-				$crate::_init_and_read_len_prefixed_tlv_fields!(reader, {
-					$(($type, $field, $fieldty)),*
-				});
-				Ok(::lightning_macros::drop_legacy_field_definition!(Self {
-					$(
-						$field: $crate::_init_tlv_based_struct_field!($field, $fieldty)
-					),*
-				}))
+				Ok($crate::_decode_and_build!(reader, Self, {$(($type, $field, $fieldty)),*}))
 			}
 		}
 	}
@@ -1176,14 +1211,7 @@ macro_rules! impl_writeable_tlv_based_enum {
 						// Because read_tlv_fields creates a labeled loop, we cannot call it twice
 						// in the same function body. Instead, we define a closure and call it.
 						let mut f = || {
-							$crate::_init_and_read_len_prefixed_tlv_fields!(reader, {
-								$(($type, $field, $fieldty)),*
-							});
-							Ok(::lightning_macros::drop_legacy_field_definition!($st::$variant_name {
-								$(
-									$field: $crate::_init_tlv_based_struct_field!($field, $fieldty)
-								),*
-							}))
+							Ok($crate::_decode_and_build!(reader, $st::$variant_name, {$(($type, $field, $fieldty)),*}))
 						};
 						f()
 					}),*
@@ -1225,14 +1253,7 @@ macro_rules! impl_writeable_tlv_based_enum_legacy {
 						// Because read_tlv_fields creates a labeled loop, we cannot call it twice
 						// in the same function body. Instead, we define a closure and call it.
 						let mut f = || {
-							$crate::_init_and_read_len_prefixed_tlv_fields!(reader, {
-								$(($type, $field, $fieldty)),*
-							});
-							Ok(::lightning_macros::drop_legacy_field_definition!($st::$variant_name {
-								$(
-									$field: $crate::_init_tlv_based_struct_field!($field, $fieldty)
-								),*
-							}))
+							Ok($crate::_decode_and_build!(reader, $st::$variant_name, {$(($type, $field, $fieldty)),*}))
 						};
 						f()
 					}),*
@@ -1288,14 +1309,7 @@ macro_rules! impl_writeable_tlv_based_enum_upgradable {
 						// Because read_tlv_fields creates a labeled loop, we cannot call it twice
 						// in the same function body. Instead, we define a closure and call it.
 						let mut f = || {
-							$crate::_init_and_read_len_prefixed_tlv_fields!(reader, {
-								$(($type, $field, $fieldty)),*
-							});
-							Ok(Some(::lightning_macros::drop_legacy_field_definition!($st::$variant_name {
-								$(
-									$field: $crate::_init_tlv_based_struct_field!($field, $fieldty)
-								),*
-							})))
+							Ok(Some($crate::_decode_and_build!(reader, $st::$variant_name, {$(($type, $field, $fieldty)),*})))
 						};
 						f()
 					}),*
@@ -1344,14 +1358,7 @@ macro_rules! impl_writeable_tlv_based_enum_upgradable_legacy {
 						// Because read_tlv_fields creates a labeled loop, we cannot call it twice
 						// in the same function body. Instead, we define a closure and call it.
 						let mut f = || {
-							$crate::_init_and_read_len_prefixed_tlv_fields!(reader, {
-								$(($type, $field, $fieldty)),*
-							});
-							Ok(Some(::lightning_macros::drop_legacy_field_definition!($st::$variant_name {
-								$(
-									$field: $crate::_init_tlv_based_struct_field!($field, $fieldty)
-								),*
-							})))
+							Ok(Some($crate::_decode_and_build!(reader, $st::$variant_name, {$(($type, $field, $fieldty)),*})))
 						};
 						f()
 					}),*