Sublime contest - Funen's results

1. Upgrade pragma compiler at least ^0.8.* or 0.8.4



This known issue was set before at :


https://github.com/code-423n4/2021-12-sublime-findings/issues/39



using new compiler will set Optimizer improvement for Safemath, Custom error, etc. it would be saving more gas by using it.



##Occurance


PooledCreditLine.sol LenderPool.sol
 twitterVerifier.sol


2. Better way of using SafeERC20 to saving more gas



https://github.com/sublime-finance/sublimev1/blob/46536a6d25df4264c1b217bd3232af30355dcb95/contracts/PooledCreditLine/LenderPool.sol#L295

This implementation can be saving more gas 



##POC



by not declaring :

using SafeErc20 for IERC20
;



 and change into

SafeERC20.safeTransferFrom(IERC20(_borrowAsset), msg.sender, address(this), _amountToLend);




3. Rewrite struct order for saving more gas



this implementation below can be used for saving more gas



##Tool Used Manual Review

##POC

    struct PooledCreditLineConstants {
        uint128 borrowLimit;
        uint128 borrowRate;
        uint256 startsAt;
        uint256 endsAt;
        uint256 defaultsAt;
        uint256 gracePenaltyRate;
        uint256 idealCollateralRatio;
        address borrower;
        address borrowAsset;
        address collateralAsset;
        address borrowAssetStrategy;
        address collateralAssetStrategy;
    }

4. change if else statement for saving more gas

https://github.com/sublime-finance/sublime-v1/blob/46536a6d25df4264c1b217bd3232af30355dcb95/contracts/PooledCreditLine/PooledCreditLine.sol#L373

this implementation with the same logic, can be used for saving more gas (+- 12 gas)

##Tool Used Remix

##POC

// SPDX-License-Identifier: MIT
pragma solidity 0.7.6;
pragma abicoder v2;
   
contract foo{

   function isWithinLimits(
        uint256 _value,
        uint256 _min,
        uint256 _max
    ) internal pure returns (bool) {
        if (_min != 0 && _max != 0) {
            // If both min and max limits exist
            return (_value >= _min && _value <= _max);
        } else if (_min != 0) {
            // if only min limit exists
            return (_value >= _min);
        } else if (_max != 0) {
            // if only max limit exists
            return (_value <= _max);
        } else {
            // if both min and max limits don't exist
            return true;
        }
    }
}
// 67066

change to

// SPDX-License-Identifier: MIT
pragma solidity 0.7.6;
pragma abicoder v2;
   
contract foo{

   function isWithinLimits(
        uint256 _value,
        uint256 _min,
        uint256 _max
    ) internal pure returns (bool) {
        if (_min != 0 && _max != 0) {
            return (_value >= _min && _value <= _max);
        } else if ( _min != 0 || _max != 0 ) {
            return (_value >= _min || _value <= _max);
        } else {
            // if both min and max limits don't exist
            return true;
        }
    }
}
// 67054

5. Variable can be set as immutable

https://github.com/sublime-finance/sublime-v1/blob/46536a6d25df4264c1b217bd3232af30355dcb95/contracts/Verification/twitterVerifier.sol#L16

##POC

IVerification public immutable verification;