From be4165afa5609245a7ffbb89228e3d0bd05176b6 Mon Sep 17 00:00:00 2001
From: cedoor <me@cedoor.dev>
Date: Fri, 18 Nov 2022 20:04:39 +0100
Subject: [PATCH] fix(contracts): save merkle roots after updates or removal of
 members

---
 packages/contracts/contracts/Semaphore.sol | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/packages/contracts/contracts/Semaphore.sol b/packages/contracts/contracts/Semaphore.sol
index 93aaea75..dc80d425 100644
--- a/packages/contracts/contracts/Semaphore.sol
+++ b/packages/contracts/contracts/Semaphore.sol
@@ -111,6 +111,10 @@ contract Semaphore is ISemaphore, SemaphoreGroups {
         uint8[] calldata proofPathIndices
     ) external override onlyGroupAdmin(groupId) {
         _updateMember(groupId, identityCommitment, newIdentityCommitment, proofSiblings, proofPathIndices);
+
+        uint256 merkleTreeRoot = getMerkleTreeRoot(groupId);
+
+        groups[groupId].merkleRootCreationDates[merkleTreeRoot] = block.timestamp;
     }
 
     /// @dev See {ISemaphore-removeMember}.
@@ -121,6 +125,10 @@ contract Semaphore is ISemaphore, SemaphoreGroups {
         uint8[] calldata proofPathIndices
     ) external override onlyGroupAdmin(groupId) {
         _removeMember(groupId, identityCommitment, proofSiblings, proofPathIndices);
+
+        uint256 merkleTreeRoot = getMerkleTreeRoot(groupId);
+
+        groups[groupId].merkleRootCreationDates[merkleTreeRoot] = block.timestamp;
     }
 
     /// @dev See {ISemaphore-verifyProof}.