Merge pull request #94 from aave/feat/mint-event-account-for-interest

feat/mint event account for interest

.gitignore

@@ -16,4 +16,3 @@ coverage
 .coverage_cache
 .coverage_contracts
 coverage.json
-

contracts/interfaces/IScaledBalanceToken.sol

@@ -28,4 +28,11 @@ interface IScaledBalanceToken {
    * @return The scaled total supply
    **/
   function scaledTotalSupply() external view returns (uint256);
+
+  /**
+   * @notice Returns last index interest was accrued to the user's balance
+   * @param user The address of the user
+   * @return The last index interest was accrued to the user's balance
+   **/
+  function getPreviousIndex(address user) external view returns (uint256);
 }

contracts/protocol/libraries/helpers/Errors.sol

@@ -72,16 +72,8 @@ library Errors {
   string public constant MATH_MULTIPLICATION_OVERFLOW = '48';
   string public constant MATH_ADDITION_OVERFLOW = '49';
   string public constant MATH_DIVISION_BY_ZERO = '50';
-  string public constant RL_LIQUIDITY_INDEX_OVERFLOW = '51'; //  Liquidity index overflows uint128
-  string public constant RL_VARIABLE_BORROW_INDEX_OVERFLOW = '52'; //  Variable borrow index overflows uint128
-  string public constant RL_LIQUIDITY_RATE_OVERFLOW = '53'; //  Liquidity rate overflows uint128
-  string public constant RL_VARIABLE_BORROW_RATE_OVERFLOW = '54'; //  Variable borrow rate overflows uint128
-  string public constant RL_STABLE_BORROW_RATE_OVERFLOW = '55'; //  Stable borrow rate overflows uint128
   string public constant CT_INVALID_MINT_AMOUNT = '56'; //invalid amount to mint
-  string public constant P_FAILED_REPAY_WITH_COLLATERAL = '57';
   string public constant CT_INVALID_BURN_AMOUNT = '58'; //invalid amount to burn
-  string public constant P_FAILED_COLLATERAL_SWAP = '60';
-  string public constant P_INVALID_EQUAL_ASSETS_TO_SWAP = '61';
   string public constant P_REENTRANCY_NOT_ALLOWED = '62';
   string public constant P_CALLER_MUST_BE_AN_ATOKEN = '63';
   string public constant P_IS_PAUSED = '64'; // Deprecated 'Pool is paused'
@@ -97,7 +89,7 @@ library Errors {
   string public constant P_INCONSISTENT_PARAMS_LENGTH = '74';
   string public constant UL_INVALID_INDEX = '77';
   string public constant P_NOT_CONTRACT = '78';
-  string public constant SDT_STABLE_DEBT_OVERFLOW = '79';
+  string public constant SDT_STABLE_DEBT_OVERFLOW = '79'; // Deprecated moved to general `HLP_UINT128_OVERFLOW`
   string public constant SDT_BURN_EXCEEDS_BALANCE = '80';
   string public constant VL_BORROW_CAP_EXCEEDED = '81';
   string public constant RC_INVALID_BORROW_CAP = '82';
@@ -114,4 +106,5 @@ library Errors {
   string public constant PC_FLASHLOAN_PREMIUMS_MISMATCH = '95';
   string public constant PC_FLASHLOAN_PREMIUM_INVALID = '96';
   string public constant RC_INVALID_LIQUIDATION_PROTOCOL_FEE = '97';
+  string public constant HLP_UINT128_OVERFLOW = '98';
 }

contracts/protocol/libraries/helpers/Helpers.sol

@@ -2,6 +2,7 @@
 pragma solidity 0.8.7;
 
 import {IERC20} from '../../../dependencies/openzeppelin/contracts/IERC20.sol';
+import {Errors} from './Errors.sol';
 import {DataTypes} from '../types/DataTypes.sol';
 
 /**
@@ -44,4 +45,9 @@ library Helpers {
       IERC20(reserve.variableDebtTokenAddress).balanceOf(user)
     );
   }
+
+  function castUint128(uint256 input) internal pure returns (uint128) {
+    require(input <= type(uint128).max, Errors.HLP_UINT128_OVERFLOW);
+    return uint128(input);
+  }
 }

contracts/protocol/libraries/logic/BorrowLogic.sol

@@ -147,8 +147,6 @@ library BorrowLogic {
     reserve.updateState(reserveCache);
 
     ValidationLogic.validateRepay(
-      params.lastBorrower,
-      params.lastBorrowTimestamp,
       reserveCache,
       params.amount,
       interestRateMode,

contracts/protocol/libraries/logic/ReserveLogic.sol

@@ -12,6 +12,7 @@ import {MathUtils} from '../math/MathUtils.sol';
 import {WadRayMath} from '../math/WadRayMath.sol';
 import {PercentageMath} from '../math/PercentageMath.sol';
 import {Errors} from '../helpers/Errors.sol';
+import {Helpers} from '../helpers/Helpers.sol';
 import {DataTypes} from '../types/DataTypes.sol';
 
 /**
@@ -120,9 +121,7 @@ library ReserveLogic {
     uint256 result = amountToLiquidityRatio + WadRayMath.RAY;
 
     result = result.rayMul(reserve.liquidityIndex);
-    require(result <= type(uint128).max, Errors.RL_LIQUIDITY_INDEX_OVERFLOW);
-
-    reserve.liquidityIndex = uint128(result);
+    reserve.liquidityIndex = Helpers.castUint128(result);
   }
 
   /**
@@ -190,13 +189,10 @@ library ReserveLogic {
       reserveCache.nextAvgStableBorrowRate,
       reserveCache.reserveConfiguration.getReserveFactorMemory()
     );
-    require(vars.nextLiquidityRate <= type(uint128).max, Errors.RL_LIQUIDITY_RATE_OVERFLOW);
-    require(vars.nextStableRate <= type(uint128).max, Errors.RL_STABLE_BORROW_RATE_OVERFLOW);
-    require(vars.nextVariableRate <= type(uint128).max, Errors.RL_VARIABLE_BORROW_RATE_OVERFLOW);
 
-    reserve.currentLiquidityRate = uint128(vars.nextLiquidityRate);
-    reserve.currentStableBorrowRate = uint128(vars.nextStableRate);
-    reserve.currentVariableBorrowRate = uint128(vars.nextVariableRate);
+    reserve.currentLiquidityRate = Helpers.castUint128(vars.nextLiquidityRate);
+    reserve.currentStableBorrowRate = Helpers.castUint128(vars.nextStableRate);
+    reserve.currentVariableBorrowRate = Helpers.castUint128(vars.nextVariableRate);
 
     emit ReserveDataUpdated(
       reserveAddress,
@@ -296,11 +292,7 @@ library ReserveLogic {
       reserveCache.nextLiquidityIndex = cumulatedLiquidityInterest.rayMul(
         reserveCache.currLiquidityIndex
       );
-      require(
-        reserveCache.nextLiquidityIndex <= type(uint128).max,
-        Errors.RL_LIQUIDITY_INDEX_OVERFLOW
-      );
-      reserve.liquidityIndex = uint128(reserveCache.nextLiquidityIndex);
+      reserve.liquidityIndex = Helpers.castUint128(reserveCache.nextLiquidityIndex);
 
       //as the liquidity rate might come only from stable rate loans, we need to ensure
       //that there is actual variable debt before accumulating
@@ -312,11 +304,7 @@ library ReserveLogic {
         reserveCache.nextVariableBorrowIndex = cumulatedVariableBorrowInterest.rayMul(
           reserveCache.currVariableBorrowIndex
         );
-        require(
-          reserveCache.nextVariableBorrowIndex <= type(uint128).max,
-          Errors.RL_VARIABLE_BORROW_INDEX_OVERFLOW
-        );
-        reserve.variableBorrowIndex = uint128(reserveCache.nextVariableBorrowIndex);
+        reserve.variableBorrowIndex = Helpers.castUint128(reserveCache.nextVariableBorrowIndex);
       }
     }
 

contracts/protocol/libraries/logic/ValidationLogic.sol

@@ -247,8 +247,6 @@ library ValidationLogic {
 
   /**
    * @notice Validates a repay action
-   * @param lastBorrower The address of the last borrower
-   * @param lastBorrowTimestamp The timestamp for last borrow
    * @param reserveCache The cached data of the reserve
    * @param amountSent The amount sent for the repayment. Can be an actual value or uint(-1)
    * @param rateMode The interest rate mode of the debt being repaid
@@ -257,8 +255,6 @@ library ValidationLogic {
    * @param variableDebt The borrow balance of the user
    */
   function validateRepay(
-    address lastBorrower,
-    uint40 lastBorrowTimestamp,
     DataTypes.ReserveCache memory reserveCache,
     uint256 amountSent,
     DataTypes.InterestRateMode rateMode,
@@ -272,8 +268,17 @@ library ValidationLogic {
 
     require(amountSent > 0, Errors.VL_INVALID_AMOUNT);
 
+    uint256 variableDebtPreviousIndex = IScaledBalanceToken(reserveCache.variableDebtTokenAddress)
+      .getPreviousIndex(onBehalfOf);
+
+    uint40 stableRatePreviousTimestamp = IStableDebtToken(reserveCache.stableDebtTokenAddress)
+      .getUserLastUpdated(onBehalfOf);
+
     require(
-      lastBorrower != onBehalfOf || lastBorrowTimestamp != uint40(block.timestamp),
+      (stableRatePreviousTimestamp < uint40(block.timestamp) &&
+        DataTypes.InterestRateMode(rateMode) == DataTypes.InterestRateMode.STABLE) ||
+        (variableDebtPreviousIndex < reserveCache.nextVariableBorrowIndex &&
+          DataTypes.InterestRateMode(rateMode) == DataTypes.InterestRateMode.VARIABLE),
       Errors.VL_SAME_BLOCK_BORROW_REPAY
     );
 

contracts/protocol/libraries/types/DataTypes.sol

@@ -106,8 +106,6 @@ library DataTypes {
     uint256 amount;
     uint256 rateMode;
     address onBehalfOf;
-    address lastBorrower;
-    uint40 lastBorrowTimestamp;
     bool useATokens;
   }
 

contracts/protocol/pool/Pool.sol

@@ -172,8 +172,6 @@ contract Pool is VersionedInitializable, IPool, PoolStorage {
         _addressesProvider.getPriceOracle()
       )
     );
-    _lastBorrower = msg.sender;
-    _lastBorrowTimestamp = uint40(block.timestamp);
   }
 
   /// @inheritdoc IPool
@@ -187,15 +185,7 @@ contract Pool is VersionedInitializable, IPool, PoolStorage {
       BorrowLogic.executeRepay(
         _reserves[asset],
         _usersConfig[onBehalfOf],
-        DataTypes.ExecuteRepayParams(
-          asset,
-          amount,
-          rateMode,
-          onBehalfOf,
-          _lastBorrower,
-          _lastBorrowTimestamp,
-          false
-        )
+        DataTypes.ExecuteRepayParams(asset, amount, rateMode, onBehalfOf, false)
       );
   }
 
@@ -223,15 +213,7 @@ contract Pool is VersionedInitializable, IPool, PoolStorage {
       BorrowLogic.executeRepay(
         _reserves[asset],
         _usersConfig[onBehalfOf],
-        DataTypes.ExecuteRepayParams(
-          asset,
-          amount,
-          rateMode,
-          onBehalfOf,
-          _lastBorrower,
-          _lastBorrowTimestamp,
-          false
-        )
+        DataTypes.ExecuteRepayParams(asset, amount, rateMode, onBehalfOf, false)
       );
   }
 
@@ -246,15 +228,7 @@ contract Pool is VersionedInitializable, IPool, PoolStorage {
       BorrowLogic.executeRepay(
         _reserves[asset],
         _usersConfig[onBehalfOf],
-        DataTypes.ExecuteRepayParams(
-          asset,
-          amount,
-          rateMode,
-          onBehalfOf,
-          _lastBorrower,
-          _lastBorrowTimestamp,
-          true
-        )
+        DataTypes.ExecuteRepayParams(asset, amount, rateMode, onBehalfOf, true)
       );
   }
 

contracts/protocol/pool/PoolStorage.sol

@@ -41,8 +41,4 @@ contract PoolStorage {
   mapping(address => bool) _authorizedFlashBorrowers;
 
   uint256 internal _flashLoanPremiumToProtocol;
-
-  address internal _lastBorrower;
-
-  uint40 internal _lastBorrowTimestamp;
 }

contracts/protocol/tokenization/AToken.sol

@@ -5,6 +5,7 @@ import {IERC20} from '../../dependencies/openzeppelin/contracts/IERC20.sol';
 import {SafeERC20} from '../../dependencies/openzeppelin/contracts/SafeERC20.sol';
 import {VersionedInitializable} from '../libraries/aave-upgradeability/VersionedInitializable.sol';
 import {Errors} from '../libraries/helpers/Errors.sol';
+import {Helpers} from '../libraries/helpers/Helpers.sol';
 import {WadRayMath} from '../libraries/math/WadRayMath.sol';
 import {IPool} from '../../interfaces/IPool.sol';
 import {IAToken} from '../../interfaces/IAToken.sol';
@@ -111,14 +112,25 @@ contract AToken is
   ) external override onlyPool {
     uint256 amountScaled = amount.rayDiv(index);
     require(amountScaled != 0, Errors.CT_INVALID_BURN_AMOUNT);
-    _burn(user, amountScaled);
+
+    uint256 scaledBalance = super.balanceOf(user);
+    uint256 accumulatedInterest = scaledBalance.rayMul(index) -
+      scaledBalance.rayMul(_userState[user].additionalData);
+
+    _burn(user, Helpers.castUint128(amountScaled));
 
     if (receiverOfUnderlying != address(this)) {
       IERC20(_underlyingAsset).safeTransfer(receiverOfUnderlying, amount);
     }
 
+    _userState[user].additionalData = Helpers.castUint128(index);
+
     emit Transfer(user, address(0), amount);
-    emit Burn(user, receiverOfUnderlying, amount, index);
+    if (accumulatedInterest > amount) {
+      emit Mint(user, accumulatedInterest - amount, index);
+    } else {
+      emit Burn(user, receiverOfUnderlying, amount - accumulatedInterest, index);
+    }
   }
 
   /// @inheritdoc IAToken
@@ -127,16 +139,21 @@ contract AToken is
     uint256 amount,
     uint256 index
   ) external override onlyPool returns (bool) {
-    uint256 previousBalance = super.balanceOf(user);
-
     uint256 amountScaled = amount.rayDiv(index);
     require(amountScaled != 0, Errors.CT_INVALID_MINT_AMOUNT);
-    _mint(user, amountScaled);
+
+    uint256 scaledBalance = super.balanceOf(user);
+    uint256 accumulatedInterest = scaledBalance.rayMul(index) -
+      scaledBalance.rayMul(_userState[user].additionalData);
+
+    _mint(user, Helpers.castUint128(amountScaled));
+
+    _userState[user].additionalData = Helpers.castUint128(index);
 
     emit Transfer(address(0), user, amount);
-    emit Mint(user, amount, index);
+    emit Mint(user, amount + accumulatedInterest, index);
 
-    return previousBalance == 0;
+    return scaledBalance == 0;
   }
 
   /// @inheritdoc IAToken
@@ -151,7 +168,7 @@ contract AToken is
     // The amount to mint can easily be very small since it is a fraction of the interest ccrued.
     // In that case, the treasury will experience a (very small) loss, but it
     // wont cause potentially valid transactions to fail.
-    _mint(treasury, amount.rayDiv(index));
+    _mint(treasury, Helpers.castUint128(amount.rayDiv(index)));
 
     emit Transfer(address(0), treasury, amount);
     emit Mint(treasury, amount, index);
@@ -211,6 +228,11 @@ contract AToken is
     return super.totalSupply();
   }
 
+  /// @inheritdoc IScaledBalanceToken
+  function getPreviousIndex(address user) public view virtual override returns (uint256) {
+    return _userState[user].additionalData;
+  }
+
   /**
    * @notice Returns the address of the Aave treasury, receiving the fees on this aToken
    * @return Address of the Aave treasury
@@ -294,7 +316,7 @@ contract AToken is
     uint256 fromBalanceBefore = super.balanceOf(from).rayMul(index);
     uint256 toBalanceBefore = super.balanceOf(to).rayMul(index);
 
-    super._transfer(from, to, amount.rayDiv(index));
+    super._transfer(from, to, Helpers.castUint128(amount.rayDiv(index)));
 
     if (validate) {
       pool.finalizeTransfer(underlyingAsset, from, to, amount, fromBalanceBefore, toBalanceBefore);
@@ -312,7 +334,7 @@ contract AToken is
   function _transfer(
     address from,
     address to,
-    uint256 amount
+    uint128 amount
   ) internal override {
     _transfer(from, to, amount, true);
   }