- Added credit delegation interface to debt tokens.

contracts/interfaces/ICreditDelegationToken.sol

@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: agpl-3.0
+pragma solidity 0.6.12;
+
+interface ICreditDelegationToken {
+  event BorrowAllowanceDelegated(
+    address indexed fromUser,
+    address indexed toUser,
+    address asset,
+    uint256 amount
+  );
+
+  /**
+   * @dev delegates borrowing power to a user on the specific debt token
+   * @param delegatee the address receiving the delegated borrowing power
+   * @param amount the maximum amount being delegated. Delegation will still
+   * respect the liquidation constraints (even if delegated, a delegatee cannot
+   * force a delegator HF to go below 1)
+   **/
+  function approveDelegation(address delegatee, uint256 amount) external;
+
+  /**
+   * @dev returns the borrow allowance of the user
+   * @param fromUser The user to giving allowance
+   * @param toUser The user to give allowance to
+   * @return the current allowance of toUser
+   **/
+  function borrowAllowance(address fromUser, address toUser) external view returns (uint256);
+}

contracts/protocol/tokenization/base/DebtTokenBase.sol

@@ -2,6 +2,7 @@
 pragma solidity 0.6.12;
 
 import {ILendingPool} from '../../../interfaces/ILendingPool.sol';
+import {ICreditDelegationToken} from '../../../interfaces/ICreditDelegationToken.sol';
 import {
   VersionedInitializable
 } from '../../libraries/aave-upgradeability/VersionedInitializable.sol';
@@ -14,14 +15,11 @@ import {Errors} from '../../libraries/helpers/Errors.sol';
  * @author Aave
  */
 
-abstract contract DebtTokenBase is IncentivizedERC20, VersionedInitializable {
-  event BorrowAllowanceDelegated(
-    address indexed fromUser,
-    address indexed toUser,
-    address asset,
-    uint256 amount
-  );
-
+abstract contract DebtTokenBase is
+  IncentivizedERC20,
+  VersionedInitializable,
+  ICreditDelegationToken
+{
   address public immutable UNDERLYING_ASSET_ADDRESS;
   ILendingPool public immutable POOL;
 
@@ -73,7 +71,7 @@ abstract contract DebtTokenBase is IncentivizedERC20, VersionedInitializable {
    * respect the liquidation constraints (even if delegated, a delegatee cannot
    * force a delegator HF to go below 1)
    **/
-  function approveDelegation(address delegatee, uint256 amount) external {
+  function approveDelegation(address delegatee, uint256 amount) external override {
     _borrowAllowances[_msgSender()][delegatee] = amount;
     emit BorrowAllowanceDelegated(_msgSender(), delegatee, UNDERLYING_ASSET_ADDRESS, amount);
   }
@@ -84,7 +82,12 @@ abstract contract DebtTokenBase is IncentivizedERC20, VersionedInitializable {
    * @param toUser The user to give allowance to
    * @return the current allowance of toUser
    **/
-  function borrowAllowance(address fromUser, address toUser) external view returns (uint256) {
+  function borrowAllowance(address fromUser, address toUser)
+    external
+    view
+    override
+    returns (uint256)
+  {
     return _borrowAllowances[fromUser][toUser];
   }