feat: proposal guardian expires

.gitignore

@@ -8,3 +8,4 @@ cache
 artifacts
 yarn-error.log
 .DS_Store
+yarn.lock

contracts/GovernorBravoDelegate.sol

@@ -157,7 +157,10 @@ contract GovernorBravoDelegate is
         bytes32 r,
         bytes32 s
     ) public returns (uint) {
-        require(proposalId == proposalCount + 1, "GovernorBravo::proposeBySig: invalid proposal id");
+        require(
+            proposalId == proposalCount + 1,
+            "GovernorBravo::proposeBySig: invalid proposal id"
+        );
         address signatory;
         {
             bytes32 domainSeparator = keccak256(
@@ -380,7 +383,9 @@ contract GovernorBravoDelegate is
         Proposal storage proposal = proposals[proposalId];
 
         // Proposer or proposalGuardian can cancel
-        if (msg.sender != proposal.proposer && msg.sender != proposalGuardian) {
+        if (
+            msg.sender != proposal.proposer && msg.sender != proposalGuardian()
+        ) {
             require(
                 (comp.getPriorVotes(proposal.proposer, block.number - 1) <
                     proposalThreshold),
@@ -658,6 +663,17 @@ contract GovernorBravoDelegate is
         return (whitelistAccountExpirations[account] > block.timestamp);
     }
 
+    /**
+     * @notice View function which returns the current proposal guardian
+     * @return The address of the current proposal guardian. If the proposal guardian expiry has passed, address(0) is returned.
+     */
+    function proposalGuardian() public view returns (address) {
+        return
+            _proposalGuardianExpiry >= block.timestamp
+                ? _proposalGuardian
+                : address(0);
+    }
+
     /**
      * @notice Admin function for setting the voting delay
      * @param newVotingDelay new voting delay, in blocks
@@ -755,16 +771,23 @@ contract GovernorBravoDelegate is
     /**
      * @notice Admin function for setting the proposalGuardian. ProposalGuardian can cancel proposals
      * @param account Account to set proposalGuardian to (0x0 to remove proposalGuardian)
+     * @param expiry Timestamp at which the set proposal guardian will expire
      */
-    function _setProposalGuardian(address account) external {
+    function _setProposalGuardian(address account, uint96 expiry) external {
         require(
             msg.sender == admin,
             "GovernorBravo::_setProposalGuardian: admin only"
         );
-        address oldProposalGuardian = proposalGuardian;
-        proposalGuardian = account;
 
-        emit ProposalGuardianSet(oldProposalGuardian, proposalGuardian);
+        emit ProposalGuardianSet(
+            _proposalGuardian,
+            _proposalGuardianExpiry,
+            account,
+            expiry
+        );
+
+        _proposalGuardian = account;
+        _proposalGuardianExpiry = expiry;
     }
 
     /**

contracts/GovernorBravoInterfaces.sol

@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: BSD-3-Clause
 pragma solidity ^0.8.10;
 
-
 contract GovernorBravoEvents {
     /// @notice An event emitted when a new proposal is created
     event ProposalCreated(uint id, address proposer, address[] targets, uint[] values, string[] signatures, bytes[] calldatas, uint startBlock, uint endBlock, string description);
@@ -50,7 +49,11 @@ contract GovernorBravoEvents {
     event WhitelistGuardianSet(address oldGuardian, address newGuardian);
 
     /// @notice Emitted when the proposalGuardian is set
-    event ProposalGuardianSet(address oldProposalGuardian, address newProposalGuardian);
+    event ProposalGuardianSet(
+        address oldProposalGuardian, 
+        uint96 oldProposalGuardianExpiry, 
+        address newProposalGuardian, 
+        uint newProposalGuardianExpiry);
 }
 
 contract GovernorBravoDelegatorStorage {
@@ -64,15 +67,13 @@ contract GovernorBravoDelegatorStorage {
     address public implementation;
 }
 
-
 /**
  * @title Storage for Governor Bravo Delegate
  * @notice For future upgrades, do not change GovernorBravoDelegateStorageV1. Create a new
  * contract which implements GovernorBravoDelegateStorageV1 and following the naming convention
  * GovernorBravoDelegateStorageVX.
  */
 contract GovernorBravoDelegateStorageV1 is GovernorBravoDelegatorStorage {
-
     /// @notice The delay before voting on a proposal may take place, once proposed, in blocks
     uint public votingDelay;
 
@@ -100,7 +101,6 @@ contract GovernorBravoDelegateStorageV1 is GovernorBravoDelegatorStorage {
     /// @notice The latest proposal for each proposer
     mapping (address => uint) public latestProposalIds;
 
-
     struct Proposal {
         /// @notice Unique id for looking up a proposal
         uint id;
@@ -183,7 +183,10 @@ contract GovernorBravoDelegateStorageV2 is GovernorBravoDelegateStorageV1 {
 
 contract GovernorBravoDelegateStorageV3 is GovernorBravoDelegateStorageV2 {
     /// @notice Address which has the ability to cancel proposals
-    address public proposalGuardian;
+    address internal _proposalGuardian;
+
+    /// @notice Timestamp at which the proposalGuardian stored in the `_proposalGuardian` variable is set to expire
+    uint96 internal _proposalGuardianExpiry;
 }
 
 interface TimelockInterface {

test/ForkTestSimulateUpgrade.ts

@@ -11,6 +11,7 @@ import {
   reset,
   impersonateAccount,
   loadFixture,
+  time,
 } from "@nomicfoundation/hardhat-network-helpers";
 
 describe("ForkTestSimulateUpgrade", function () {
@@ -186,12 +187,19 @@ describe("ForkTestSimulateUpgrade", function () {
     );
     const [signer] = await ethers.getSigners();
     const setProposalGuardianSelector = ethers
-      .id("_setProposalGuardian(address)")
+      .id("_setProposalGuardian(address,uint96)")
       .substring(0, 10);
     const setProposalGuardianData =
       setProposalGuardianSelector +
       ethers.AbiCoder.defaultAbiCoder()
-        .encode(["address"], [signer.address])
+        .encode(
+          ["address", "uint96"],
+          [
+            signer.address,
+            (await time.latest()) +
+              6 * 30 * 24 * 60 * 60 /* Expire in 6 months */,
+          ]
+        )
         .slice(2);
 
     expect(await governorBravoDelegator.proposalGuardian()).to.equal(

test/GovernorBravo.ts

@@ -687,7 +687,10 @@ describe("Governor Bravo", function () {
       const { governorBravo, otherAccount } = await loadFixture(deployFixtures);
       const proposalId = await proposeAndPass(governorBravo);
 
-      await governorBravo._setProposalGuardian(otherAccount);
+      await governorBravo._setProposalGuardian(
+        otherAccount,
+        (await time.latest()) + 1000
+      );
       await governorBravo.connect(otherAccount).cancel(proposalId);
     });
 
@@ -1225,7 +1228,9 @@ describe("Governor Bravo", function () {
     it("Set Proposal Guardian: admin only", async function () {
       const { governorBravo, otherAccount } = await loadFixture(deployFixtures);
       await expect(
-        governorBravo.connect(otherAccount)._setProposalGuardian(otherAccount)
+        governorBravo
+          .connect(otherAccount)
+          ._setProposalGuardian(otherAccount, (await time.latest()) + 1000)
       ).to.be.revertedWith("GovernorBravo::_setProposalGuardian: admin only");
       expect(await governorBravo.proposalGuardian()).to.equal(
         ethers.ZeroAddress
@@ -1234,13 +1239,32 @@ describe("Governor Bravo", function () {
 
     it("Set Proposal Guardian: happy path", async function () {
       const { governorBravo, otherAccount } = await loadFixture(deployFixtures);
-      await expect(governorBravo._setProposalGuardian(otherAccount))
+      const expiryTimestamp = (await time.latest()) + 1000;
+      await expect(
+        governorBravo._setProposalGuardian(otherAccount, expiryTimestamp)
+      )
         .to.emit(governorBravo, "ProposalGuardianSet")
-        .withArgs(ethers.ZeroAddress, otherAccount.address);
+        .withArgs(ethers.ZeroAddress, 0, otherAccount.address, expiryTimestamp);
       expect(await governorBravo.proposalGuardian()).to.equal(
         otherAccount.address
       );
     });
+
+    it("Set Proposal Guardian: removed after expiration", async function () {
+      const { governorBravo, otherAccount } = await loadFixture(deployFixtures);
+      const expiryTimestamp = (await time.latest()) + 1000;
+
+      await governorBravo._setProposalGuardian(otherAccount, expiryTimestamp);
+
+      expect(await governorBravo.proposalGuardian()).to.equal(
+        otherAccount.address
+      );
+
+      await time.increase(1001);
+      expect(await governorBravo.proposalGuardian()).to.equal(
+        ethers.ZeroAddress
+      );
+    });
   });
 
   describe("Whitelist", function () {