fix: rewards delegate

Author: rhlsthrm

contracts/compound/CErc20RewardsDelegate.sol

@@ -5,6 +5,22 @@ import "./CErc20Delegate.sol";
 import "./EIP20Interface.sol";
 
 contract CErc20RewardsDelegate is CErc20Delegate {
+  function _getExtensionFunctions() public pure virtual override returns (bytes4[] memory functionSelectors) {
+    uint8 fnsCount = 2;
+
+    bytes4[] memory superFunctionSelectors = super._getExtensionFunctions();
+    functionSelectors = new bytes4[](superFunctionSelectors.length + fnsCount);
+
+    for (uint256 i = 0; i < superFunctionSelectors.length; i++) {
+      functionSelectors[i] = superFunctionSelectors[i];
+    }
+
+    functionSelectors[--fnsCount + superFunctionSelectors.length] = this.claim.selector;
+    functionSelectors[--fnsCount + superFunctionSelectors.length] = this.approve.selector;
+
+    require(fnsCount == 0, "use the correct array length");
+  }
+  
   /// @notice A reward token claim function
   /// to be overridden for use cases where rewardToken needs to be pulled in
   function claim() external {}