refactor(flash-loan): remove erc3156

src/Blue.sol

@@ -3,8 +3,8 @@ pragma solidity 0.8.20;
 
 import {IIrm} from "src/interfaces/IIrm.sol";
 import {IERC20} from "src/interfaces/IERC20.sol";
-import {IERC3156FlashLender} from "src/interfaces/IERC3156FlashLender.sol";
-import {IERC3156FlashBorrower, FLASH_BORROWER_SUCCESS_HASH} from "src/interfaces/IERC3156FlashBorrower.sol";
+import {IFlashLender} from "src/interfaces/IFlashLender.sol";
+import {IFlashBorrower} from "src/interfaces/IFlashBorrower.sol";
 
 import {Errors} from "./libraries/Errors.sol";
 import {SharesMath} from "src/libraries/SharesMath.sol";
@@ -16,7 +16,7 @@ uint256 constant WAD = 1e18;
 uint256 constant MAX_FEE = 0.2e18;
 uint256 constant ALPHA = 0.5e18;
 
-contract Blue is IERC3156FlashLender {
+contract Blue is IFlashLender {
     using SharesMath for uint256;
     using FixedPointMathLib for uint256;
     using SafeTransferLib for IERC20;
@@ -249,29 +249,13 @@ contract Blue is IERC3156FlashLender {
 
     // Flash Loans.
 
-    /// @inheritdoc IERC3156FlashLender
-    function maxFlashLoan(address token) external view returns (uint256) {
-        return IERC20(token).balanceOf(address(this));
-    }
-
-    /// @inheritdoc IERC3156FlashLender
-    function flashFee(address, uint256) external pure returns (uint256) {
-        return 0;
-    }
-
-    /// @inheritdoc IERC3156FlashLender
-    function flashLoan(IERC3156FlashBorrower receiver, address token, uint256 amount, bytes calldata data)
-        external
-        returns (bool)
-    {
+    /// @inheritdoc IFlashLender
+    function flashLoan(IFlashBorrower receiver, address token, uint256 amount, bytes calldata data) external {
         IERC20(token).safeTransfer(address(receiver), amount);
 
-        bytes32 successHash = receiver.onFlashLoan(msg.sender, token, amount, 0, data);
-        require(successHash == FLASH_BORROWER_SUCCESS_HASH, Errors.INVALID_SUCCESS_HASH);
+        receiver.onFlashLoan(msg.sender, token, amount, data);
 
         IERC20(token).safeTransferFrom(address(receiver), address(this), amount);
-
-        return true;
     }
 
     // Position management.

src/interfaces/IFlashBorrower.sol

@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity >=0.5.0;
+
+interface IFlashBorrower {
+    /**
+     * @dev Receives a flash loan.
+     * @param initiator The initiator of the loan.
+     * @param token The token lent.
+     * @param amount The amount of tokens lent.
+     * @param data Arbitrary data structure, intended to contain user-defined parameters.
+     */
+    function onFlashLoan(address initiator, address token, uint256 amount, bytes calldata data) external;
+}

src/interfaces/IFlashLender.sol

@@ -0,0 +1,15 @@
+// SPDX-License-Identifier: UNLICENSED
+pragma solidity >=0.5.0;
+
+import {IFlashBorrower} from "src/interfaces/IFlashBorrower.sol";
+
+interface IFlashLender {
+    /**
+     * @dev Initiate a flash loan.
+     * @param receiver The receiver of the tokens in the loan, and the receiver of the callback.
+     * @param token The token lent.
+     * @param amount The amount of tokens lent.
+     * @param data Arbitrary data structure, intended to contain user-defined parameters.
+     */
+    function flashLoan(IFlashBorrower receiver, address token, uint256 amount, bytes calldata data) external;
+}

src/mocks/FlashBorrowerMock.sol

@@ -1,31 +1,26 @@
 // SPDX-License-Identifier: UNLICENSED
 pragma solidity ^0.8.0;
 
-import {IERC3156FlashLender} from "src/interfaces/IERC3156FlashLender.sol";
-import {IERC3156FlashBorrower, FLASH_BORROWER_SUCCESS_HASH} from "src/interfaces/IERC3156FlashBorrower.sol";
+import {IFlashLender} from "src/interfaces/IFlashLender.sol";
+import {IFlashBorrower} from "src/interfaces/IFlashBorrower.sol";
 
 import {ERC20, SafeTransferLib} from "solmate/utils/SafeTransferLib.sol";
 
-contract FlashBorrowerMock is IERC3156FlashBorrower {
+contract FlashBorrowerMock is IFlashBorrower {
     using SafeTransferLib for ERC20;
 
-    IERC3156FlashLender private immutable _LENDER;
+    IFlashLender private immutable _LENDER;
 
-    constructor(IERC3156FlashLender lender) {
+    constructor(IFlashLender lender) {
         _LENDER = lender;
     }
 
     /* EXTERNAL */
 
-    /// @inheritdoc IERC3156FlashBorrower
-    function onFlashLoan(address, address token, uint256 amount, uint256 fee, bytes calldata)
-        external
-        returns (bytes32)
-    {
+    /// @inheritdoc IFlashBorrower
+    function onFlashLoan(address, address token, uint256 amount, bytes calldata) external {
         require(msg.sender == address(_LENDER), "invalid lender");
 
-        ERC20(token).safeApprove(address(_LENDER), amount + fee);
-
-        return FLASH_BORROWER_SUCCESS_HASH;
+        ERC20(token).safeApprove(address(_LENDER), amount);
     }
 }

test/forge/Blue.t.sol

@@ -696,6 +696,8 @@ contract BlueTest is Test {
         blue.supply(market, amount, address(this));
 
         blue.flashLoan(flashBorrower, address(borrowableAsset), amount, bytes(""));
+
+        assertEq(borrowableAsset.balanceOf(address(blue)), amount, "balanceOf");
     }
 }