Using the addition operator instead of plus-equals saves gas
Not inlining costs 20 to 40 gas because of two extra JUMP instructions and additional stack operations needed for function calls.
Contracts are allowed to override their parents’ functions and change the visibility from external to public and can save gas by doing so.
https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L159 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L172 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L179 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L219 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Quest.sol#L140 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Quest.sol#L145 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Quest.sol#L150
If a function modifier or require such as onlyOwner/onlyX is used, the function will revert if a normal user tries to pay the function. Marking the function as payable will lower the gas cost for legitimate callers because the compiler will not include checks for whether a payment was provided. The extra opcodes avoided are CALLVALUE(2), DUP1(3), ISZERO(3), PUSH2(3), JUMPI(10), PUSH1(3), DUP1(3), REVERT(0), JUMPDEST(1), POP(2) which costs an average of about 21 gas per call to the function, in addition to the extra deployment cost.
https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Quest.sol#L150 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Quest.sol#L63 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Quest.sol#L57 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L142 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L159 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L165 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L172 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L179 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/QuestFactory.sol#L186 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/RabbitHoleReceipt.sol#L65 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/RabbitHoleReceipt.sol#L71 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/RabbitHoleReceipt.sol#L77 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/RabbitHoleReceipt.sol#L83 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/RabbitHoleReceipt.sol#L90 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/RabbitHoleTickets.sol#L54 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/RabbitHoleTickets.sol#L60 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/RabbitHoleTickets.sol#L66 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/RabbitHoleTickets.sol#L73
Recommended Mitigation Steps
Functions guaranteed to revert when called by normal users can be marked payable.
Saves ~13 gas per instance
https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Erc1155Quest.sol#L13 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Erc20Quest.sol#L17 https://github.com/rabbitholegg/quest-protocol/blob/8c4c1f71221570b14a0479c216583342bd652d8d/contracts/Quest.sol#L26