From 9117273c085365c857979c793557ae94a8bdd62c Mon Sep 17 00:00:00 2001
From: Jack Grigg <jack@electriccoin.co>
Date: Wed, 28 Jul 2021 22:51:43 +0100
Subject: [PATCH] Fix bug in `Builder` initialization of `Circuit` struct

`rcv` was being used correctly outside the circuit to derive `cv_net`
but then `Circuit` was just storing 0. The `round_trip` test passed
because it uses `rcv = 0` everywhere.
---
 src/builder.rs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/builder.rs b/src/builder.rs
index 641ad8b7..7070b084 100644
--- a/src/builder.rs
+++ b/src/builder.rs
@@ -130,7 +130,7 @@ impl ActionInfo {
     /// [orchardsend]: https://zips.z.cash/protocol/nu5.pdf#orchardsend
     fn build(self, mut rng: impl RngCore) -> (Action<SigningMetadata>, Circuit) {
         let v_net = self.value_sum().expect("already checked this");
-        let cv_net = ValueCommitment::derive(v_net, self.rcv);
+        let cv_net = ValueCommitment::derive(v_net, self.rcv.clone());
 
         let nf_old = self.spend.note.nullifier(&self.spend.fvk);
         let sender_address = self.spend.fvk.default_address();
@@ -196,7 +196,7 @@ impl ActionInfo {
                 v_new: Some(note.value()),
                 psi_new: Some(note.rseed().psi(&note.rho())),
                 rcm_new: Some(note.rseed().rcm(&note.rho())),
-                rcv: Some(ValueCommitTrapdoor::zero()),
+                rcv: Some(self.rcv),
             },
         )
     }