From 062a02da1a93e45e043c9cfeddae09998abe8c6b Mon Sep 17 00:00:00 2001
From: Matt Corallo <git@bluematt.me>
Date: Thu, 18 Oct 2018 14:58:56 -0400
Subject: [PATCH] Add a second Readable trait for state args, clean macros
 slightly

---
 src/util/ser.rs        | 10 ++++++++++
 src/util/ser_macros.rs |  8 +++++---
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/util/ser.rs b/src/util/ser.rs
index 92cc66b81..5429c0e66 100644
--- a/src/util/ser.rs
+++ b/src/util/ser.rs
@@ -82,6 +82,16 @@ pub trait Readable<R>
 	fn read(reader: &mut R) -> Result<Self, DecodeError>;
 }
 
+/// A trait that various higher-level rust-lightning types implement allowing them to be read in
+/// from a Read given some additional set of arguments which is required to deserialize.
+pub trait ReadableArgs<R, P>
+	where Self: Sized,
+	      R: Read
+{
+	/// Reads a Self in from the given Read
+	fn read(reader: &mut R, params: P) -> Result<Self, DecodeError>;
+}
+
 macro_rules! impl_writeable_primitive {
 	($val_type:ty, $meth_write:ident, $len: expr, $meth_read:ident) => {
 		impl Writeable for $val_type {
diff --git a/src/util/ser_macros.rs b/src/util/ser_macros.rs
index 09a319fb4..900270f31 100644
--- a/src/util/ser_macros.rs
+++ b/src/util/ser_macros.rs
@@ -2,13 +2,15 @@ macro_rules! impl_writeable {
 	($st:ident, $len: expr, {$($field:ident),*}) => {
 		impl Writeable for $st {
 			fn write<W: Writer>(&self, w: &mut W) -> Result<(), ::std::io::Error> {
-				w.size_hint($len);
+				if $len != 0 {
+					w.size_hint($len);
+				}
 				$( self.$field.write(w)?; )*
 				Ok(())
 			}
 		}
 
-		impl<R: Read> Readable<R> for $st {
+		impl<R: ::std::io::Read> Readable<R> for $st {
 			fn read(r: &mut R) -> Result<Self, DecodeError> {
 				Ok(Self {
 					$($field: Readable::read(r)?),*
@@ -29,7 +31,7 @@ macro_rules! impl_writeable_len_match {
 			}
 		}
 
-		impl<R: Read> Readable<R> for $st {
+		impl<R: ::std::io::Read> Readable<R> for $st {
 			fn read(r: &mut R) -> Result<Self, DecodeError> {
 				Ok(Self {
 					$($field: Readable::read(r)?),*
-- 
2.39.5