ToB improvement: emit event when Flashloan taken (#731)

* ToB improvement: emit event when Flashloan taken

* Changes after review - add comment

* Set optimizers run to 100

Makefile

@@ -19,8 +19,8 @@ build :; forge clean && forge build
 
 # Tests
 test :; forge test --no-match-test "testLoad|invariant|test_regression" # --ffi # enable if you need the `ffi` cheat code on HEVM
-test-with-gas-report :; FOUNDRY_PROFILE=optimized forge test --no-match-test "testLoad|invariant|test_regression" --gas-report # --ffi # enable if you need the `ffi` cheat code on HEVM
-test-load :; FOUNDRY_PROFILE=optimized forge test --match-test testLoad --gas-report
+test-with-gas-report :; forge test --no-match-test "testLoad|invariant|test_regression" --gas-report # --ffi # enable if you need the `ffi` cheat code on HEVM
+test-load :; forge test --match-test testLoad --gas-report
 test-invariant :; eval QUOTE_PRECISION=${QUOTE_PRECISION} COLLATERAL_PRECISION=${COLLATERAL_PRECISION} forge t --mt invariant --nmc RegressionTest
 test-invariant-erc20 :; eval QUOTE_PRECISION=${QUOTE_PRECISION} COLLATERAL_PRECISION=${COLLATERAL_PRECISION} forge t --mt invariant --nmc RegressionTest --mc ERC20
 test-invariant-erc721 :; eval QUOTE_PRECISION=${QUOTE_PRECISION} forge t --mt invariant --nmc RegressionTest --mc ERC721

brownie-config.yml

@@ -17,6 +17,7 @@ compiler:
  version: 0.8.14
  optimizer:
  enabled: true
+ runs: 100
  remappings:
  - "@ds-math=lib/ds-math/src/"
  - "@openzeppelin/contracts=lib/openzeppelin-contracts/contracts"

foundry.toml

@@ -17,10 +17,8 @@ block_timestamp = 1_672_372_127
 block_number = 16_295_000
 fork_block_number = 16_295_000
 rpc_storage_caching = { chains = ["mainnet"], endpoints = "all" }
-
-[profile.optimized]
-optimizer = true
-optimizer_runs = 200
+optimizer = true
+optimizer_runs = 100
 
 [fuzz]
 runs = 300

src/base/FlashloanablePool.sol

@@ -21,7 +21,7 @@ abstract contract FlashloanablePool is Pool {
  * @notice Called by flashloan borrowers to borrow liquidity which must be repaid in the same transaction.
  * @param receiver_ Address of the contract which implements the appropriate interface to receive tokens.
  * @param token_ Address of the ERC20 token caller wants to borrow.
- * @param amount_ The amount of tokens to borrow.
+ * @param amount_ The denormalized amount (dependent upon token precision) of tokens to borrow.
  * @param data_ User-defined calldata passed to the receiver.
  * @return success_ True if flashloan was successful.
  */
@@ -54,6 +54,8 @@ abstract contract FlashloanablePool is Pool {
  if (tokenContract.balanceOf(address(this)) != initialBalance) revert FlashloanIncorrectBalance();
 
  success_ = true;
+
+ emit Flashloan(address(receiver_), token_, amount_);
  }
 
  /**

src/interfaces/pool/commons/IPoolEvents.sol

@@ -315,6 +315,18 @@ interface IPoolEvents {
  uint256 lpForfeited
  );
 
+ /**
+ * @notice Emitted when a flashloan is taken from pool.
+ * @param receiver The address receiving the flashloan.
+ * @param token The address of token flashloaned from pool.
+ * @param amount The amount of tokens flashloaned from pool.
+ */
+ event Flashloan(
+ address indexed receiver,
+ address indexed token,
+ uint256 amount
+ );
+
  /**
  * @notice Emitted when a loan Neutral Price is restamped.
  * @param borrower Identifies the loan to update the Neutral Price.

tests/forge/unit/ERC20Pool/ERC20PoolFlashloan.t.sol

@@ -3,7 +3,7 @@ pragma solidity 0.8.14;
 
 import '@openzeppelin/contracts/token/ERC20/ERC20.sol';
 
-import { ERC20HelperContract }  from './ERC20DSTestPlus.sol';
+import { ERC20HelperContract } from './ERC20DSTestPlus.sol';
 import {
  FlashloanBorrower,
  SomeDefiStrategy,
@@ -79,6 +79,9 @@ contract ERC20PoolFlashloanTest is ERC20HelperContract {
  // Use a flashloan to interact with the strategy
  assertEq(_collateral.balanceOf(address(flasher)), 0);
  assertTrue(!flasher.callbackInvoked());
+
+ vm.expectEmit(true, true, false, true);
+ emit Flashloan(address(flasher), address(_collateral), loanAmount);
  _pool.flashLoan(flasher, address(_collateral), loanAmount, new bytes(0));
  assertTrue(flasher.callbackInvoked());
  assertEq(_collateral.balanceOf(address(flasher)), 3.5 * 1e18);
@@ -228,6 +231,9 @@ contract ERC20PoolFlashloanPrecisionTest is ERC20HelperContract {
  // Use a flashloan to interact with the strategy
  assertEq(WBTC.balanceOf(address(flasher)), 0);
  assertTrue(!flasher.callbackInvoked());
+
+ vm.expectEmit(true, true, false, true);
+ emit Flashloan(address(flasher), address(WBTC), loanAmount);
  _pool.flashLoan(flasher, address(WBTC), loanAmount, new bytes(0));
  assertTrue(flasher.callbackInvoked());
  assertEq(WBTC.balanceOf(address(flasher)), 0.35 * 1e8);
@@ -258,6 +264,9 @@ contract ERC20PoolFlashloanPrecisionTest is ERC20HelperContract {
  // Use a flashloan to interact with the strategy
  assertEq(USDC.balanceOf(address(flasher)), 0);
  assertTrue(!flasher.callbackInvoked());
+
+ vm.expectEmit(true, true, false, true);
+ emit Flashloan(address(flasher), address(USDC), loanAmount);
  _pool.flashLoan(flasher, address(USDC), loanAmount, new bytes(0));
  assertTrue(flasher.callbackInvoked());
  assertEq(USDC.balanceOf(address(flasher)), 350 * 1e6);

tests/forge/unit/ERC721Pool/ERC721PoolFlashloan.t.sol

@@ -78,6 +78,9 @@ contract ERC721PoolFlashloanTest is ERC721HelperContract {
  // Use a flashloan to interact with the strategy
  assertEq(_quote.balanceOf(address(flasher)), 0);
  assertTrue(!flasher.callbackInvoked());
+
+ vm.expectEmit(true, true, false, true);
+ emit Flashloan(address(flasher), address(_quote), loanAmount);
  _pool.flashLoan(flasher, address(_quote), loanAmount, new bytes(0));
  assertTrue(flasher.callbackInvoked());
  assertEq(_quote.balanceOf(address(flasher)), 3.5 * 1e18);