From 906e203663e5983e020702c140e88492f2c55119 Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@electriccoin.co>
Date: Mon, 4 Dec 2023 20:24:39 +0000
Subject: [PATCH] zcash_primitives: Move Sapling `HashSer` impl into
 `merkle_tree` module

The `HashSer` trait will remain in `zcash_primitives` while the Sapling
type it is implemented for moves to `sapling-crypto`.

Part of zcash/librustzcash#1044.
---
 zcash_primitives/src/merkle_tree.rs  | 17 +++++++++++++++++
 zcash_primitives/src/sapling/tree.rs | 19 -------------------
 2 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/zcash_primitives/src/merkle_tree.rs b/zcash_primitives/src/merkle_tree.rs
index 66c13807d..21a6a1f3f 100644
--- a/zcash_primitives/src/merkle_tree.rs
+++ b/zcash_primitives/src/merkle_tree.rs
@@ -23,6 +23,23 @@ pub trait HashSer {
     fn write<W: Write>(&self, writer: W) -> io::Result<()>;
 }
 
+impl HashSer for sapling::Node {
+    fn read<R: Read>(mut reader: R) -> io::Result<Self> {
+        let mut repr = [0u8; 32];
+        reader.read_exact(&mut repr)?;
+        Option::from(Self::from_bytes(repr)).ok_or_else(|| {
+            io::Error::new(
+                io::ErrorKind::InvalidData,
+                "Non-canonical encoding of Jubjub base field value.",
+            )
+        })
+    }
+
+    fn write<W: Write>(&self, mut writer: W) -> io::Result<()> {
+        writer.write_all(&self.to_bytes())
+    }
+}
+
 impl HashSer for MerkleHashOrchard {
     fn read<R: Read>(mut reader: R) -> io::Result<Self>
     where
diff --git a/zcash_primitives/src/sapling/tree.rs b/zcash_primitives/src/sapling/tree.rs
index 7e75791cc..b3b9f87ff 100644
--- a/zcash_primitives/src/sapling/tree.rs
+++ b/zcash_primitives/src/sapling/tree.rs
@@ -5,13 +5,11 @@ use lazy_static::lazy_static;
 use subtle::CtOption;
 
 use std::fmt;
-use std::io::{self, Read, Write};
 
 use super::{
     note::ExtractedNoteCommitment,
     pedersen_hash::{pedersen_hash, Personalization},
 };
-use crate::merkle_tree::HashSer;
 
 pub const NOTE_COMMITMENT_TREE_DEPTH: u8 = 32;
 pub type CommitmentTree =
@@ -123,23 +121,6 @@ impl Hashable for Node {
     }
 }
 
-impl HashSer for Node {
-    fn read<R: Read>(mut reader: R) -> io::Result<Self> {
-        let mut repr = [0u8; 32];
-        reader.read_exact(&mut repr)?;
-        Option::from(Self::from_bytes(repr)).ok_or_else(|| {
-            io::Error::new(
-                io::ErrorKind::InvalidData,
-                "Non-canonical encoding of Jubjub base field value.",
-            )
-        })
-    }
-
-    fn write<W: Write>(&self, mut writer: W) -> io::Result<()> {
-        writer.write_all(&self.to_bytes())
-    }
-}
-
 impl From<Node> for bls12_381::Scalar {
     fn from(node: Node) -> Self {
         node.0