Y2k Finance contest - seyni's results

GAS

[G-01] Use custom errors instead of revert string

Custom errors from Solidity 0.8.4 are cheaper than revert strings (cheaper deployment cost and runtime cost when the revert condition is met).

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol

091:        require((shares = previewDeposit(id, assets)) != 0, "ZERO_SHARES");
116:        require(
            msg.sender == owner || isApprovedForAll(owner, receiver),
            "Only owner can withdraw, or owner has approved receiver for all"
        );

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/oracles/PegOracle.sol

023:        require(_oracle1 != address(0), "oracle1 cannot be the zero address");
024:        require(_oracle2 != address(0), "oracle2 cannot be the zero address");
025:        require(_oracle1 != _oracle2, "Cannot be same Oracle");
028:        require(
                (priceFeed1.decimals() == priceFeed2.decimals()),
                "Decimals must be the same"
            );
098:        require(price1 > 0, "Chainlink price <= 0");
099:        require(
                answeredInRound1 >= roundID1,
                "RoundID from Oracle is outdated!"
            );
103:        require(timeStamp1 != 0, "Timestamp == 0 !");
121:        require(price2 > 0, "Chainlink price <= 0");
122:        require(
                answeredInRound2 >= roundID2,
                "RoundID from Oracle is outdated!"
            );
126:        require(timeStamp2 != 0, "Timestamp == 0 !");

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/rewards/StakingRewards.sol

096:        require(amount != 0, "Cannot stake 0");
119:        require(amount > 0, "Cannot withdraw 0");
202:        require(
                rewardRate <= balance.div(rewardsDuration),
                "Provided reward too high"
            );
217:        require(
                tokenAddress != address(stakingToken),
                "Cannot withdraw the staking token"
            );
226:        require(
                block.timestamp > periodFinish,
                "Previous rewards period must be complete before changing the duration for the new period"
            );

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/Vault.sol

165:        require((shares = previewDeposit(id, assets)) != 0, "ZeroValue");
187:        require(msg.value > 0, "ZeroValue");

[G-02] Long error message

Reducing the size of errors decrease deployment cost and runtime cost when the revert condition is met.

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol

116:        require(
                msg.sender == owner || isApprovedForAll(owner, receiver),
                "Only owner can withdraw, or owner has approved receiver for all"
            );

[G-03] i++ instead of ++i and inline unchecked{++i} could be used

i++ cost 5 more gas per iteration than ++i and the increment could be unchecked.

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/Vault.sol

443:        for (uint256 i = 0; i < epochsLength(); i++) {

[G-04] Useless explicit initialization of variables to default value

Explicitly initializing a variable with its default value wastes gas.

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/rewards/StakingRewards.sol

036:    uint256 public periodFinish = 0;

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/Vault.sol

443:        for (uint256 i = 0; i < epochsLength(); i++) {

[G-05] epochsLength() should be cached

epochsLength() is called twice per loop :

• when checking if the condition i < epochsLength() is true

• when checking if the condition i == epochsLength() - 1 is true

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/Vault.sol

443:        for (uint256 i = 0; i < epochsLength(); i++) {
445:        if (i == epochsLength() - 1) {

[G-06] Boolean comparison

Using if(bool) or if(!bool) instead of if(bool == true) or if(bool == false) cost less gas.

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/Controller.sol

093:        if(vault.idExists(epochEnd) == false)
211:        if(insrVault.idExists(epochEnd) == false || riskVault.idExists(epochEnd) == false)

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/rewards/RewardsFactory.sol

096:        if(Vault(_insrToken).idExists(_epochEnd) == false || Vault(_riskToken).idExists(_epochEnd) == false)

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/Vault.sol

096:        if((block.timestamp < id) && idDepegged[id] == false)
215:        if(
                msg.sender != owner &&
                isApprovedForAll(owner, receiver) == false)

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/main/src/Vault.sol

314:        if(idExists[epochEnd] == true)

[G-07] EMPTY variable is not consistently used and use more gas

Using the variable EMPTY use more deployment and runtime gas than hardcoding "".

And the variable is not always used (see below).

File : https://github.com/code-423n4/2022-09-y2k-finance/blob/2175c044af98509261e4147edeb48e1036773771/src/SemiFungibleVault.sol

069:    ) ERC1155("") {