enh: address PR comments

- make comments more concise
- clarify in comment that native asset can not be rescued
- move custom interface into a /dependencies dir
- order read/write functions on ATokenVaultMerklRewardsClaim contract and interface

Author: aa-eyup

src/ATokenVaultMerklRewardClaimer.sol

@@ -8,20 +8,12 @@ import {IERC20} from "@openzeppelin/interfaces/IERC20.sol";
 
 import {ATokenVault} from "./ATokenVault.sol";
 import {IATokenVaultMerklRewardClaimer} from "./interfaces/IATokenVaultMerklRewardClaimer.sol";
-
-interface IMerklDistributor {
-    function claim(
-        address[] calldata users,
-        address[] calldata tokens,
-        uint256[] calldata amounts,
-        bytes32[][] calldata proofs
-    ) external;
-}
+import {IMerklDistributor} from "./dependencies/merkl/DistributorInterface.sol";
 
 /**
  * @title ATokenVaultMerklRewardClaimer
  * @author Aave Protocol
- * @notice A contract that allows the owner to claim Merkl rewards for the ATokenVault
+ * @notice ATokenVault, with Merkl reward claiming capability
  */
 contract ATokenVaultMerklRewardClaimer is ATokenVault, IATokenVaultMerklRewardClaimer {
     /**
@@ -34,19 +26,6 @@ contract ATokenVaultMerklRewardClaimer is ATokenVault, IATokenVaultMerklRewardCl
         ATokenVault(underlying, referralCode, poolAddressesProvider)
     {}
 
-    /// @inheritdoc IATokenVaultMerklRewardClaimer
-    function getMerklDistributor() external view override returns (address) {
-        return _s.merklDistributor;
-    }
-
-    /// @inheritdoc IATokenVaultMerklRewardClaimer
-    function setMerklDistributor(address merklDistributor) external override onlyOwner {
-        require(merklDistributor != address(0), "ZERO_ADDRESS_NOT_VALID");
-        address currentMerklDistributor = _s.merklDistributor;
-        _s.merklDistributor = merklDistributor;
-        emit MerklDistributorUpdated(currentMerklDistributor, merklDistributor);
-    }
-
     /// @inheritdoc IATokenVaultMerklRewardClaimer
     function claimMerklRewards(address[] calldata rewardTokens, uint256[] calldata amounts, bytes32[][] calldata proofs)
         public
@@ -63,7 +42,7 @@ contract ATokenVaultMerklRewardClaimer is ATokenVault, IATokenVaultMerklRewardCl
 
         // The claim function does not return a list of tokens and amounts actually received.
         // It is possible for rewards to be in aTokens, the underlying asset or some other token.
-        // If necessary the owner can use IATokenVault.emergencyRescue(...) to rescue the non-aToken rewards.
+        // If necessary the owner can use IATokenVault.emergencyRescue(...) to rescue the non-aToken rewards and non-native rewards.
         IMerklDistributor(_s.merklDistributor).claim(users, rewardTokens, amounts, proofs);
         // Do not attempt to accrue yield as it can be delegated to subsequent calls to this contract.
         // We do not need to accrue before claiming because new shares are not granted anywhere (rewards are socialized across all current share holders).
@@ -72,4 +51,17 @@ contract ATokenVaultMerklRewardClaimer is ATokenVault, IATokenVaultMerklRewardCl
 
         emit MerklRewardsClaimed(rewardTokens, amounts);
     }
+
+    /// @inheritdoc IATokenVaultMerklRewardClaimer
+    function setMerklDistributor(address merklDistributor) external override onlyOwner {
+        require(merklDistributor != address(0), "ZERO_ADDRESS_NOT_VALID");
+        address currentMerklDistributor = _s.merklDistributor;
+        _s.merklDistributor = merklDistributor;
+        emit MerklDistributorUpdated(currentMerklDistributor, merklDistributor);
+    }
+
+    /// @inheritdoc IATokenVaultMerklRewardClaimer
+    function getMerklDistributor() external view override returns (address) {
+        return _s.merklDistributor;
+    }
 }

src/ATokenVaultStorage.sol

@@ -20,7 +20,7 @@ abstract contract ATokenVaultStorage {
         uint40 __deprecated_gap;
         // as a fraction of 1e18
         uint64 fee;
-        // Merkl distributor contract address called to claim Merkl rewards
+        // Merkl distributor contract
         address merklDistributor;
         // Reserved storage space to allow for layout changes in the future
         uint256[49] __gap;

src/dependencies/merkl/DistributorInterface.sol

@@ -0,0 +1,14 @@
+// SPDX-License-Identifier: UNLICENSED
+// Based on implementation from https://github.com/AngleProtocol/merkl-contracts/blob/b7bd0e65a3f366e4041bc83494cbd981f8852b16/contracts/Distributor.sol#L202
+// All Rights Reserved © AaveCo
+
+pragma solidity ^0.8.10;
+
+interface IMerklDistributor {
+    function claim(
+        address[] calldata users,
+        address[] calldata tokens,
+        uint256[] calldata amounts,
+        bytes32[][] calldata proofs
+    ) external;
+}

src/interfaces/IATokenVaultMerklRewardClaimer.sol

@@ -26,19 +26,6 @@ interface IATokenVaultMerklRewardClaimer {
      */
     event MerklDistributorUpdated(address indexed oldMerklDistributor, address indexed newMerklDistributor);
 
-    /**
-     * @notice Getter for the contract address called to claim Merkl rewards
-     * @return Address of the Merkl distributor contract
-     */
-    function getMerklDistributor() external view returns (address);
-
-    /**
-     * @notice Sets the Merkl distributor address for the vault uses to claim Merkl rewards.
-     * @dev Only callable by the owner
-     * @param merklDistributor Address of the new Merkl distributor contract
-     */
-    function setMerklDistributor(address merklDistributor) external;
-
     /**
      * @notice Claims Merkl rewards earned by deposits from this contract through the Merkl distributor contract
      * @dev Only callable by the owner
@@ -51,4 +38,17 @@ interface IATokenVaultMerklRewardClaimer {
      */
     function claimMerklRewards(address[] calldata rewardTokens, uint256[] calldata amounts, bytes32[][] calldata proofs)
         external;
+
+    /**
+     * @notice Sets the Merkl distributor address for the vault uses to claim Merkl rewards.
+     * @dev Only callable by the owner
+     * @param merklDistributor Address of the new Merkl distributor contract
+     */
+    function setMerklDistributor(address merklDistributor) external;
+
+    /**
+     * @notice Getter for the contract address called to claim Merkl rewards
+     * @return Address of the Merkl distributor contract
+     */
+    function getMerklDistributor() external view returns (address);
 }