Add Compound V3 client contract

.github/workflows/ci.yml

@@ -9,6 +9,7 @@ on:
 
 env:
   FOUNDRY_PROFILE: ci
+  MAINNET_RPC_URL: ${{ secrets.MAINNET_RPC_URL }}
   OPTIMISM_RPC_URL: ${{ secrets.OPTIMISM_RPC_URL }}
 
 jobs:
@@ -25,7 +26,7 @@ jobs:
       - name: Build contracts
         run: |
           forge --version
-          forge build --sizes
+          forge build
   test:
     runs-on: ubuntu-latest
     steps:
@@ -49,21 +50,22 @@ jobs:
         with:
           version: nightly
 
-      - name: Install scopelint
-        uses: engineerd/configurator@v0.0.8
-        with:
-          name: scopelint
-          repo: ScopeLift/scopelint
-          fromGitHubReleases: true
-          version: latest
-          pathInArchive: scopelint-x86_64-linux/scopelint
-          urlTemplate: https://github.com/ScopeLift/scopelint/releases/download/{{version}}/scopelint-x86_64-linux.tar.xz
-          token: ${{ secrets.GITHUB_TOKEN }}
+      # - name: Install scopelint
+      #   uses: engineerd/configurator@v0.0.8
+      #   with:
+      #     name: scopelint
+      #     repo: ScopeLift/scopelint
+      #     fromGitHubReleases: true
+      #     version: latest
+      #     pathInArchive: scopelint-x86_64-linux/scopelint
+      #     urlTemplate: https://github.com/ScopeLift/scopelint/releases/download/{{version}}/scopelint-x86_64-linux.tar.xz
+      #     token: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Check formatting
-        run: |
-          scopelint --version
-          scopelint check
+        run: forge fmt --check
+        # run: |
+        #   scopelint --version
+        #   scopelint check
 
   # TODO figure out why this is failing and uncomment
   # slither-analyze:

.gitmodules

@@ -11,3 +11,6 @@
 	path = lib/openzeppelin-contracts
 	url = https://github.com/openzeppelin/openzeppelin-contracts
 	branch = v4.8.0
+[submodule "lib/comet"]
+	path = lib/comet
+	url = https://github.com/davidlaprade/comet

foundry.toml

@@ -18,6 +18,7 @@
   optimizer = false
 
 [rpc_endpoints]
+  mainnet = "${MAINNET_RPC_URL}"
   optimism = "${OPTIMISM_RPC_URL}"
 
 [fmt]

src/ATokenFlexVoting.sol

@@ -4,15 +4,11 @@ pragma solidity 0.8.10;
 // forgefmt: disable-start
 import {AToken} from "aave-v3-core/contracts/protocol/tokenization/AToken.sol";
 import {MintableIncentivizedERC20} from "aave-v3-core/contracts/protocol/tokenization/base/MintableIncentivizedERC20.sol";
-import {Errors} from "aave-v3-core/contracts/protocol/libraries/helpers/Errors.sol";
-import {GPv2SafeERC20} from "aave-v3-core/contracts/dependencies/gnosis/contracts/GPv2SafeERC20.sol";
-import {IAToken} from "aave-v3-core/contracts/interfaces/IAToken.sol";
 import {IAaveIncentivesController} from "aave-v3-core/contracts/interfaces/IAaveIncentivesController.sol";
 import {IPool} from "aave-v3-core/contracts/interfaces/IPool.sol";
-import {SafeCast} from "@openzeppelin/contracts/utils/math/SafeCast.sol";
 import {Checkpoints} from "@openzeppelin/contracts/utils/Checkpoints.sol";
-import {IFractionalGovernor} from "src/interfaces/IFractionalGovernor.sol";
-import {IVotingToken} from "src/interfaces/IVotingToken.sol";
+
+import {FlexVotingClient} from "src/FlexVotingClient.sol";
 // forgefmt: disable-end
 
 /// @notice This is an extension of Aave V3's AToken contract which makes it possible for AToken
@@ -39,46 +35,13 @@ import {IVotingToken} from "src/interfaces/IVotingToken.sol";
 /// The original AToken that this contract extends is viewable here:
 ///
 ///   https://github.com/aave/aave-v3-core/blob/c38c6276/contracts/protocol/tokenization/AToken.sol
-contract ATokenFlexVoting is AToken {
-  using SafeCast for uint256;
+contract ATokenFlexVoting is AToken, FlexVotingClient {
   using Checkpoints for Checkpoints.History;
 
-  /// @notice The voting options corresponding to those used in the Governor.
-  enum VoteType {
-    Against,
-    For,
-    Abstain
-  }
-
-  /// @notice Data structure to store vote preferences expressed by depositors.
-  struct ProposalVote {
-    uint128 againstVotes;
-    uint128 forVotes;
-    uint128 abstainVotes;
-  }
-
-  /// @notice Map proposalId to an address to whether they have voted on this proposal.
-  mapping(uint256 => mapping(address => bool)) private proposalVotersHasVoted;
-
-  /// @notice Map proposalId to vote totals expressed on this proposal.
-  mapping(uint256 => ProposalVote) public proposalVotes;
-
-  /// @notice The governor contract associated with this governance token. It
-  /// must be one that supports fractional voting, e.g. GovernorCountingFractional.
-  IFractionalGovernor public immutable GOVERNOR;
-
-  /// @notice Mapping from address to stored (not rebased) balance checkpoint history.
-  mapping(address => Checkpoints.History) private balanceCheckpoints;
-
-  /// @notice History of total stored (not rebased) balances.
-  Checkpoints.History private totalDepositCheckpoints;
-
   /// @dev Constructor.
   /// @param _pool The address of the Pool contract
   /// @param _governor The address of the flex-voting-compatible governance contract.
-  constructor(IPool _pool, address _governor) AToken(_pool) {
-    GOVERNOR = IFractionalGovernor(_governor);
-  }
+  constructor(IPool _pool, address _governor) AToken(_pool) FlexVotingClient(_governor) {}
 
   // forgefmt: disable-start
   //===========================================================================
@@ -109,7 +72,7 @@ contract ATokenFlexVoting is AToken {
       params
     );
 
-    selfDelegate();
+    FlexVotingClient._selfDelegate();
   }
 
   /// Note: this has been modified from Aave v3's MintableIncentivizedERC20 to
@@ -118,8 +81,10 @@ contract ATokenFlexVoting is AToken {
   /// @inheritdoc MintableIncentivizedERC20
   function _burn(address account, uint128 amount) internal override {
     MintableIncentivizedERC20._burn(account, amount);
-    _checkpointRawBalanceOf(account);
-    totalDepositCheckpoints.push(totalDepositCheckpoints.latest() - amount);
+    FlexVotingClient._checkpointRawBalanceOf(account);
+    FlexVotingClient.totalBalanceCheckpoints.push(
+      FlexVotingClient.totalBalanceCheckpoints.latest() - amount
+    );
   }
 
   /// Note: this has been modified from Aave v3's MintableIncentivizedERC20 to
@@ -128,8 +93,10 @@ contract ATokenFlexVoting is AToken {
   /// @inheritdoc MintableIncentivizedERC20
   function _mint(address account, uint128 amount) internal override {
     MintableIncentivizedERC20._mint(account, amount);
-    _checkpointRawBalanceOf(account);
-    totalDepositCheckpoints.push(totalDepositCheckpoints.latest() + amount);
+    FlexVotingClient._checkpointRawBalanceOf(account);
+    FlexVotingClient.totalBalanceCheckpoints.push(
+      FlexVotingClient.totalBalanceCheckpoints.latest() + amount
+    );
   }
 
   /// @dev This has been modified from Aave v3's AToken contract to checkpoint raw balances
@@ -145,136 +112,16 @@ contract ATokenFlexVoting is AToken {
     bool validate
   ) internal virtual override {
     AToken._transfer(from, to, amount, validate);
-    _checkpointRawBalanceOf(from);
-    _checkpointRawBalanceOf(to);
+    FlexVotingClient._checkpointRawBalanceOf(from);
+    FlexVotingClient._checkpointRawBalanceOf(to);
   }
   //===========================================================================
   // END: Aave overrides
   //===========================================================================
   // forgefmt: disable-end
 
-  // Self-delegation cannot be done in the constructor because the aToken is
-  // just a proxy -- it won't share an address with the implementation (i.e.
-  // this code). Instead we do it at the end of `initialize`. But even that won't
-  // handle already-initialized aTokens. For those, we'll need to self-delegate
-  // during the upgrade process. More details in these issues:
-  // https://github.com/aave/aave-v3-core/pull/774
-  // https://github.com/ScopeLift/flexible-voting/issues/16
-  function selfDelegate() public {
-    IVotingToken(GOVERNOR.token()).delegate(address(this));
-  }
-
-  /// @notice Allow a depositor to express their voting preference for a given
-  /// proposal. Their preference is recorded internally but not moved to the
-  /// Governor until `castVote` is called.
-  /// @param proposalId The proposalId in the associated Governor
-  /// @param support The depositor's vote preferences in accordance with the `VoteType` enum.
-  function expressVote(uint256 proposalId, uint8 support) external {
-    uint256 weight = getPastStoredBalance(msg.sender, GOVERNOR.proposalSnapshot(proposalId));
-    require(weight > 0, "no weight");
-
-    require(!proposalVotersHasVoted[proposalId][msg.sender], "already voted");
-    proposalVotersHasVoted[proposalId][msg.sender] = true;
-
-    if (support == uint8(VoteType.Against)) {
-      proposalVotes[proposalId].againstVotes += SafeCast.toUint128(weight);
-    } else if (support == uint8(VoteType.For)) {
-      proposalVotes[proposalId].forVotes += SafeCast.toUint128(weight);
-    } else if (support == uint8(VoteType.Abstain)) {
-      proposalVotes[proposalId].abstainVotes += SafeCast.toUint128(weight);
-    } else {
-      revert("invalid support value, must be included in VoteType enum");
-    }
-  }
-
-  /// @notice Causes this contract to cast a vote to the Governor for all of the
-  /// accumulated votes expressed by users. Uses the sum of all raw (unrebased) balances
-  /// to proportionally split its voting weight. Can be called by anyone. Can be called
-  /// multiple times during the lifecycle of a given proposal.
-  /// @param proposalId The ID of the proposal which the Pool will now vote on.
-  function castVote(uint256 proposalId) external {
-    ProposalVote storage _proposalVote = proposalVotes[proposalId];
-    require(
-      _proposalVote.forVotes + _proposalVote.againstVotes + _proposalVote.abstainVotes > 0,
-      "no votes expressed"
-    );
-    uint256 _proposalSnapshotBlockNumber = GOVERNOR.proposalSnapshot(proposalId);
-
-    // We use the snapshot of total raw balances to determine the weight with
-    // which to vote. We do this for two reasons:
-    //   (1) We cannot use the proposalVote numbers alone, since some people with
-    //       balances at the snapshot might never express their preferences. If a
-    //       large holder never expressed a preference, but this contract nevertheless
-    //       cast votes to the governor with all of its weight, then other users may
-    //       effectively have *increased* their voting weight because someone else
-    //       didn't participate, which creates all kinds of bad incentives.
-    //   (2) Other people might have already expressed their preferences on this
-    //       proposal and had those preferences submitted to the governor by an
-    //       earlier call to this function. The weight of those preferences
-    //       should still be taken into consideration when determining how much
-    //       weight to vote with this time.
-    // Using the total raw balance to proportion votes in this way means that in
-    // many circumstances this function will not cast votes with all of its
-    // weight.
-    uint256 _totalRawBalanceAtSnapshot = getPastTotalBalance(_proposalSnapshotBlockNumber);
-
-    // We need 256 bits because of the multiplication we're about to do.
-    uint256 _votingWeightAtSnapshot = IVotingToken(address(_underlyingAsset)).getPastVotes(
-      address(this), _proposalSnapshotBlockNumber
-    );
-
-    //      forVotesRaw          forVoteWeight
-    // --------------------- = ------------------
-    //     totalRawBalance      totalVoteWeight
-    //
-    // forVoteWeight = forVotesRaw * totalVoteWeight / totalRawBalance
-    uint128 _forVotesToCast = SafeCast.toUint128(
-      (_votingWeightAtSnapshot * _proposalVote.forVotes) / _totalRawBalanceAtSnapshot
-    );
-    uint128 _againstVotesToCast = SafeCast.toUint128(
-      (_votingWeightAtSnapshot * _proposalVote.againstVotes) / _totalRawBalanceAtSnapshot
-    );
-    uint128 _abstainVotesToCast = SafeCast.toUint128(
-      (_votingWeightAtSnapshot * _proposalVote.abstainVotes) / _totalRawBalanceAtSnapshot
-    );
-
-    // This param is ignored by the governor when voting with fractional
-    // weights. It makes no difference what vote type this is.
-    uint8 unusedSupportParam = uint8(VoteType.Abstain);
-
-    // Clear the stored votes so that we don't double-cast them.
-    delete proposalVotes[proposalId];
-
-    bytes memory fractionalizedVotes =
-      abi.encodePacked(_againstVotesToCast, _forVotesToCast, _abstainVotesToCast);
-    GOVERNOR.castVoteWithReasonAndParams(
-      proposalId,
-      unusedSupportParam,
-      "rolled-up vote from aToken holders", // Reason string.
-      fractionalizedVotes
-    );
-  }
-
   /// @notice Returns the _user's current balance in storage.
-  function _rawBalanceOf(address _user) internal view returns (uint256) {
+  function _rawBalanceOf(address _user) internal view override returns (uint256) {
     return _userState[_user].balance;
   }
-
-  /// @notice Checkpoints the _user's current raw balance.
-  function _checkpointRawBalanceOf(address _user) internal {
-    balanceCheckpoints[_user].push(_rawBalanceOf(_user));
-  }
-
-  /// @notice Returns the _user's balance in storage at the _blockNumber.
-  /// @param _user The account that's historical balance will be looked up.
-  /// @param _blockNumber The block at which to lookup the _user's balance.
-  function getPastStoredBalance(address _user, uint256 _blockNumber) public view returns (uint256) {
-    return balanceCheckpoints[_user].getAtProbablyRecentBlock(_blockNumber);
-  }
-
-  /// @notice Returns the total stored balance of all users at _blockNumber.
-  /// @param _blockNumber The block at which to lookup the total stored balance.
-  function getPastTotalBalance(uint256 _blockNumber) public view returns (uint256) {
-    return totalDepositCheckpoints.getAtProbablyRecentBlock(_blockNumber);
-  }
 }

src/CometFlexVoting.sol

@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity >=0.8.10;
+
+import {Comet} from "comet/Comet.sol";
+import {CometConfiguration} from "comet/CometConfiguration.sol";
+import {Checkpoints} from "@openzeppelin/contracts/utils/Checkpoints.sol";
+
+import {FlexVotingClient} from "src/FlexVotingClient.sol";
+
+/// @notice This is an extension of Compound V3's Comet contract which makes it
+/// possible for Comet token holders to still vote on governance proposals. This
+/// way, holders of governance tokens do not have to choose between earning
+/// yield on Compound and voting. They can do both.
+///
+/// This extension has the following requirements:
+///   (a) The base token must be a governance token.
+///   (b) The base token's governor contract must support flexible voting (see
+///       `GovernorCountingFractional`).
+///
+/// If these requirements are met, base token depositors can call
+/// `Comet.expressVote` to signal their preference on open governance proposals.
+/// When they do so, this extension records that preference with weight
+/// proportional to the users's Comet balance at the proposal snapshot.
+///
+/// At any point after voting preferences have been expressed, Comet's public
+/// `castVote` function may be called to roll up all internal voting records
+/// into a single delegated vote to the Governor contract -- a vote which
+/// specifies the exact For/Abstain/Against totals expressed by Comet holders.
+/// Votes can be rolled up and cast in this manner multiple times for a given
+/// proposal.
+///
+/// Participating in governance via Comet voting is completely optional. Users
+/// otherwise still supply, borrow, and hold tokens with Compound as usual.
+///
+/// The original Comet that this contract was developed against can be viewed
+/// here:
+///
+///   https://github.com/compound-finance/comet/blob/3780c06b4eaa80a8c78e0ff770a7e8a1518db75e/contracts/Comet.sol
+contract CometFlexVoting is Comet, FlexVotingClient {
+  using Checkpoints for Checkpoints.History;
+
+  /// @param _config The configuration struct for this Comet instance.
+  /// @param _governor The address of the flex-voting-compatible governance contract.
+  constructor(CometConfiguration.Configuration memory _config, address _governor)
+    Comet(_config)
+    FlexVotingClient(_governor)
+  {
+    _selfDelegate();
+  }
+
+  /// @notice Returns the current balance in storage for the `account`.
+  function _rawBalanceOf(address account) internal view override returns (uint256) {
+    int104 _principal = userBasic[account].principal;
+    return _principal > 0 ? uint256(int256(_principal)) : 0;
+  }
+
+  function _castVoteReasonString() internal override returns (string memory) {
+    return "rolled-up vote from CometFlexVoting token holders";
+  }
+
+  //===========================================================================
+  // BEGIN: Comet overrides
+  //===========================================================================
+  //
+  // This function is called any time the underlying balance is changed.
+  function updateBasePrincipal(address _account, UserBasic memory _userBasic, int104 _principalNew)
+    internal
+    override
+  {
+    Comet.updateBasePrincipal(_account, _userBasic, _principalNew);
+    FlexVotingClient._checkpointRawBalanceOf(_account);
+    FlexVotingClient.totalBalanceCheckpoints.push(uint224(totalSupplyBase));
+  }
+  //===========================================================================
+  // END: Comet overrides
+  //===========================================================================
+}