FundingPool Code Style Findings

FPL-01C: Duplicate Calculation of Same Value

Type	Severity	Location
Gas Optimization		FundingPool.sol:L43, L46

Description:

The FundingPool::deposit function will calculate the amount deposited twice redundantly.

Example:

Copy
32function deposit(uint256 amount, uint256 transferFee) external {
33    if (amount == 0) {
34        revert Errors.InvalidSendAmount();
35    }
36    uint256 preBal = IERC20Metadata(depositToken).balanceOf(address(this));
37    IERC20Metadata(depositToken).safeTransferFrom(
38        msg.sender,
39        address(this),
40        amount
41    );
42    uint256 postBal = IERC20Metadata(depositToken).balanceOf(address(this));
43    if ((postBal - preBal) != amount - transferFee) {
44        revert Errors.InvalidSendAmount();
45    }
46    balanceOf[msg.sender] += postBal - preBal;
47}

Recommendation:

We advise the value to be calculated once and stored to a local variable that is consequently utilized, optimizing the code's gas cost.

Alleviation (c740f7c6b5ebd365618fd2d7ea77370599e1ca11):

The FundingPool::deposit flow was adjusted to be more standard, transferring a surplus of transferFee rather than subtracting it from the expected transfer result and thus permitting usage of the amount variable as the value deposited. As such, we consider this optimization adequately applied.

FPL-02C: Ineffectual Usage of Safe Arithmetics

Type	Severity	Location
Language Specific		FundingPool.sol:L53

Description:

The linked mathematical operation is guaranteed to be performed safely by surrounding conditionals evaluated in either require checks or if-else constructs.

Example:

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50if (amount == 0 || amount > balanceOf[msg.sender]) {
51    revert Errors.InvalidWithdrawAmount();
52}
53balanceOf[msg.sender] -= amount;

Recommendation:

Given that safe arithmetics are toggled on by default in pragma versions of 0.8.X, we advise the linked statement to be wrapped in an unchecked code block thereby optimizing its execution cost.

Alleviation (c740f7c6b5ebd365618fd2d7ea77370599e1ca11):

The referenced arithmetic statement has been safely wrapped in an unchecked code block, optimizing its execution cost.

FPL-03C: Inefficient mapping Lookups

Type	Severity	Location
Gas Optimization		FundingPool.sol:L50, L53, L71, L77, L80, L81, L82, L83, L104, L107, L111, L112, L113

Description:

The linked statements perform key-based lookup operations on mapping declarations from storage multiple times for the same key redundantly.

Example:

Copy
49function withdraw(uint256 amount) external {
50    if (amount == 0 || amount > balanceOf[msg.sender]) {
51        revert Errors.InvalidWithdrawAmount();
52    }
53    balanceOf[msg.sender] -= amount;
54    IERC20Metadata(depositToken).safeTransfer(msg.sender, amount);
55}

Recommendation:

As the lookups internally perform an expensive keccak256 operation, we advise the lookups to be cached wherever possible to a single local declaration that either holds the value of the mapping in case of primitive types or holds a storage pointer to the struct contained.

Alleviation (c740f7c6b5):

The referenced mapping lookups have been partially optimized as certain pairs (i.e. subscriptionAmountOf in FundingPool::unsubscribe) do not make use of the capability to cache interim mapping lookups (i.e. mapping(address => uint256) storage subscriptionAmountsOfProposal = subscriptionAmountOf[loanProposal]). As such, we consider this exhibit partially alleviated.

Alleviation (37cf23668b):

Any potential caching operations for interim mapping lookups have been properly applied to the referenced lines of code within the exhibit in the latest commit hash of the report, applying this exhibit's optimization in full.

FPL-04C: Redundant Parenthesis Statement

Type	Severity	Location
Code Style		FundingPool.sol:L43

Description:

The referenced statement is redundantly wrapped in parenthesis (()).

Example:

Copy
43if ((postBal - preBal) != amount - transferFee) {

Recommendation:

We advise them to be safely omitted, increasing the legibility of the codebase.

Alleviation (c740f7c6b5ebd365618fd2d7ea77370599e1ca11):

The redundant parenthesis statement has been omitted as advised.