Merge pull request #210 from aave/feat/fix-token-events

fix: inconsistent token events

contracts/interfaces/IAToken.sol

@@ -15,10 +15,11 @@ interface IAToken is IERC20, IScaledBalanceToken, IInitializableAToken {
   /**
    * @notice Emitted after the mint action
    * @param from The address performing the mint
-   * @param value The amount being
+   * @param value The amount being minted (user entered amount + balance increase from interest)
+   * @param balanceIncrease The increase in balance since the last action of the user
    * @param index The next liquidity index of the reserve
    **/
-  event Mint(address indexed from, uint256 value, uint256 index);
+  event Mint(address indexed from, uint256 value, uint256 balanceIncrease, uint256 index);
 
   /**
    * @notice Mints `amount` aTokens to `user`
@@ -37,10 +38,17 @@ interface IAToken is IERC20, IScaledBalanceToken, IInitializableAToken {
    * @notice Emitted after aTokens are burned
    * @param from The owner of the aTokens, getting them burned
    * @param target The address that will receive the underlying
-   * @param value The amount being burned
+   * @param value The amount being burned (user entered amount - balance increase from interest)
+   * @param balanceIncrease The increase in balance since the last action of the user
    * @param index The next liquidity index of the reserve
    **/
-  event Burn(address indexed from, address indexed target, uint256 value, uint256 index);
+  event Burn(
+    address indexed from,
+    address indexed target,
+    uint256 value,
+    uint256 balanceIncrease,
+    uint256 index
+  );
 
   /**
    * @notice Emitted during the transfer action
@@ -53,6 +61,8 @@ interface IAToken is IERC20, IScaledBalanceToken, IInitializableAToken {
 
   /**
    * @notice Burns aTokens from `user` and sends the equivalent amount of underlying to `receiverOfUnderlying`
+   * @dev In some instances, the mint event could be emitted from a burn transaction
+   * if the amount to burn is less than the interest the user earned
    * @param user The owner of the aTokens, getting them burned
    * @param receiverOfUnderlying The address that will receive the underlying
    * @param amount The amount being burned

contracts/interfaces/IStableDebtToken.sol

@@ -15,7 +15,7 @@ interface IStableDebtToken is IInitializableDebtToken {
    * @notice Emitted when new stable debt is minted
    * @param user The address of the user who triggered the minting
    * @param onBehalfOf The recipient of stable debt tokens
-   * @param amount The amount minted
+   * @param amount The amount minted (user entered amount + balance increase from interest)
    * @param currentBalance The current balance of the user
    * @param balanceIncrease The increase in balance since the last action of the user
    * @param newRate The rate of the debt after the minting
@@ -36,7 +36,7 @@ interface IStableDebtToken is IInitializableDebtToken {
   /**
    * @notice Emitted when new stable debt is burned
    * @param user The address of the user
-   * @param amount The amount being burned
+   * @param amount The amount being burned (user entered amount - balance increase from interest)
    * @param currentBalance The current balance of the user
    * @param balanceIncrease The the increase in balance since the last action of the user
    * @param avgStableRate The next average stable rate after the burning
@@ -81,6 +81,8 @@ interface IStableDebtToken is IInitializableDebtToken {
    * @notice Burns debt of `user`
    * @dev The resulting rate is the weighted average between the rate of the new debt
    * and the rate of the previous debt
+   * @dev In some instances, a burn transaction will emit a mint event
+   * if the amount to burn is less than the interest the user earned
    * @param user The address of the user getting his debt burned
    * @param amount The amount of debt tokens getting burned
    * @return The total stable debt

contracts/interfaces/IVariableDebtToken.sol

@@ -15,10 +15,17 @@ interface IVariableDebtToken is IScaledBalanceToken, IInitializableDebtToken {
    * @notice Emitted after the mint action
    * @param from The address performing the mint
    * @param onBehalfOf The address of the user on which behalf minting has been performed
-   * @param value The amount to be minted
+   * @param value The amount to be minted (user entered amount + balance increase from interest)
+   * @param balanceIncrease The increase in balance since the last action of the user
    * @param index The last index of the reserve
    **/
-  event Mint(address indexed from, address indexed onBehalfOf, uint256 value, uint256 index);
+  event Mint(
+    address indexed from,
+    address indexed onBehalfOf,
+    uint256 value,
+    uint256 balanceIncrease,
+    uint256 index
+  );
 
   /**
    * @notice Mints debt token to the `onBehalfOf` address
@@ -40,13 +47,16 @@ interface IVariableDebtToken is IScaledBalanceToken, IInitializableDebtToken {
   /**
    * @notice Emitted when variable debt is burnt
    * @param user The user which debt has been burned
-   * @param amount The amount of debt being burned
+   * @param amount The amount of debt being burned (user entered amount - balance increase from interest)
+   * @param balanceIncrease The increase in balance since the last action of the user
    * @param index The index of the user
    **/
-  event Burn(address indexed user, uint256 amount, uint256 index);
+  event Burn(address indexed user, uint256 amount, uint256 balanceIncrease, uint256 index);
 
   /**
    * @notice Burns user variable debt
+   * @dev In some instances, a burn transaction will emit a mint event
+   * if the amount to burn is less than the interest the user earned
    * @param user The user which debt is burnt
    * @param amount The amount getting burned
    * @param index The variable debt index of the reserve

contracts/protocol/tokenization/AToken.sol

@@ -91,7 +91,7 @@ contract AToken is VersionedInitializable, IncentivizedERC20, IAToken {
     require(amountScaled != 0, Errors.CT_INVALID_BURN_AMOUNT);
 
     uint256 scaledBalance = super.balanceOf(user);
-    uint256 accumulatedInterest = scaledBalance.rayMul(index) -
+    uint256 balanceIncrease = scaledBalance.rayMul(index) -
       scaledBalance.rayMul(_userState[user].additionalData);
 
     _userState[user].additionalData = Helpers.castUint128(index);
@@ -102,11 +102,14 @@ contract AToken is VersionedInitializable, IncentivizedERC20, IAToken {
       IERC20(_underlyingAsset).safeTransfer(receiverOfUnderlying, amount);
     }
 
-    emit Transfer(user, address(0), amount);
-    if (accumulatedInterest > amount) {
-      emit Mint(user, accumulatedInterest - amount, index);
+    if (balanceIncrease > amount) {
+      uint256 amountToMint = balanceIncrease - amount;
+      emit Transfer(address(0), user, amountToMint);
+      emit Mint(user, amountToMint, balanceIncrease, index);
     } else {
-      emit Burn(user, receiverOfUnderlying, amount - accumulatedInterest, index);
+      uint256 amountToBurn = amount - balanceIncrease;
+      emit Transfer(user, address(0), amountToBurn);
+      emit Burn(user, receiverOfUnderlying, amountToBurn, balanceIncrease, index);
     }
   }
 
@@ -120,15 +123,16 @@ contract AToken is VersionedInitializable, IncentivizedERC20, IAToken {
     require(amountScaled != 0, Errors.CT_INVALID_MINT_AMOUNT);
 
     uint256 scaledBalance = super.balanceOf(user);
-    uint256 accumulatedInterest = scaledBalance.rayMul(index) -
+    uint256 balanceIncrease = scaledBalance.rayMul(index) -
       scaledBalance.rayMul(_userState[user].additionalData);
 
     _userState[user].additionalData = Helpers.castUint128(index);
 
     _mint(user, Helpers.castUint128(amountScaled));
 
-    emit Transfer(address(0), user, amount);
-    emit Mint(user, amount + accumulatedInterest, index);
+    uint256 amountToMint = amount + balanceIncrease;
+    emit Transfer(address(0), user, amountToMint);
+    emit Mint(user, amountToMint, balanceIncrease, index);
 
     return scaledBalance == 0;
   }

contracts/protocol/tokenization/StableDebtToken.sol

@@ -150,13 +150,14 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
         rate.rayMul(vars.amountInRay)).rayDiv(vars.nextSupply.wadToRay())
     );
 
-    _mint(onBehalfOf, amount + balanceIncrease, vars.previousSupply);
+    uint256 amountToMint = amount + balanceIncrease;
+    _mint(onBehalfOf, amountToMint, vars.previousSupply);
 
-    emit Transfer(address(0), onBehalfOf, amount + balanceIncrease);
+    emit Transfer(address(0), onBehalfOf, amountToMint);
     emit Mint(
       user,
       onBehalfOf,
-      amount,
+      amountToMint,
       currentBalance,
       balanceIncrease,
       vars.nextStableRate,
@@ -218,7 +219,7 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
     if (balanceIncrease > amount) {
       uint256 amountToMint = balanceIncrease - amount;
       _mint(user, amountToMint, previousSupply);
-      emit Transfer(address(0), user, balanceIncrease - amount);
+      emit Transfer(address(0), user, amountToMint);
       emit Mint(
         user,
         user,
@@ -232,7 +233,7 @@ contract StableDebtToken is IStableDebtToken, DebtTokenBase {
     } else {
       uint256 amountToBurn = amount - balanceIncrease;
       _burn(user, amountToBurn, previousSupply);
-      emit Transfer(address(0), user, amount - balanceIncrease);
+      emit Transfer(user, address(0), amountToBurn);
       emit Burn(user, amountToBurn, currentBalance, balanceIncrease, nextAvgStableRate, nextSupply);
     }
 

contracts/protocol/tokenization/VariableDebtToken.sol

@@ -88,15 +88,16 @@ contract VariableDebtToken is DebtTokenBase, IVariableDebtToken {
     require(amountScaled != 0, Errors.CT_INVALID_MINT_AMOUNT);
 
     uint256 scaledBalance = super.balanceOf(onBehalfOf);
-    uint256 accumulatedInterest = scaledBalance.rayMul(index) -
+    uint256 balanceIncrease = scaledBalance.rayMul(index) -
       scaledBalance.rayMul(_userState[onBehalfOf].additionalData);
 
     _userState[onBehalfOf].additionalData = Helpers.castUint128(index);
 
     _mint(onBehalfOf, Helpers.castUint128(amountScaled));
 
-    emit Transfer(address(0), onBehalfOf, amount + accumulatedInterest);
-    emit Mint(user, onBehalfOf, amount + accumulatedInterest, index);
+    uint256 amountToMint = amount + balanceIncrease;
+    emit Transfer(address(0), onBehalfOf, amountToMint);
+    emit Mint(user, onBehalfOf, amountToMint, balanceIncrease, index);
 
     return (scaledBalance == 0, scaledTotalSupply());
   }
@@ -111,19 +112,21 @@ contract VariableDebtToken is DebtTokenBase, IVariableDebtToken {
     require(amountScaled != 0, Errors.CT_INVALID_BURN_AMOUNT);
 
     uint256 scaledBalance = super.balanceOf(user);
-    uint256 accumulatedInterest = scaledBalance.rayMul(index) -
+    uint256 balanceIncrease = scaledBalance.rayMul(index) -
       scaledBalance.rayMul(_userState[user].additionalData);
 
     _userState[user].additionalData = Helpers.castUint128(index);
 
     _burn(user, Helpers.castUint128(amountScaled));
 
-    if (accumulatedInterest > amount) {
-      emit Transfer(address(0), user, accumulatedInterest - amount);
-      emit Mint(user, user, accumulatedInterest - amount, index);
+    if (balanceIncrease > amount) {
+      uint256 amountToMint = balanceIncrease - amount;
+      emit Transfer(address(0), user, amountToMint);
+      emit Mint(user, user, amountToMint, balanceIncrease, index);
     } else {
-      emit Transfer(user, address(0), amount - accumulatedInterest);
-      emit Burn(user, amount - accumulatedInterest, index);
+      uint256 amountToBurn = amount - balanceIncrease;
+      emit Transfer(user, address(0), amountToBurn);
+      emit Burn(user, amountToBurn, balanceIncrease, index);
     }
     return scaledTotalSupply();
   }