Nouns Builder contest - prasantgupta52's results

1. Use a more recent version of solidity

Use a solidity version of at least 0.8.2 to get simple compiler automatic inlining Use a solidity version of at least 0.8.3 to get better struct packing and cheaper multiple storage reads Use a solidity version of at least 0.8.4 to get custom errors, which are cheaper at deployment than revert()/require() strings Use a solidity version of at least 0.8.10 to have external calls skip contract existence checks if the external call has a return value

Links to github files

ERC1967Proxy.sol:L2 UUPS.sol:L2 ERC1967Upgrade.sol:L2 ERC721Votes.sol:L2 ERC721.sol:L2

Instances

src/lib/proxy/ERC1967Proxy.sol:2:pragma solidity ^0.8.4;
src/lib/proxy/UUPS.sol:2:pragma solidity ^0.8.4;
src/lib/proxy/ERC1967Upgrade.sol:2:pragma solidity ^0.8.4;
src/lib/token/ERC721Votes.sol:2:pragma solidity ^0.8.4;
src/lib/token/ERC721.sol:2:pragma solidity ^0.8.4;

---

2. Inline a modifier that’s only used once

Description

As notDelegated() is only used once in this contract (in function proxiableUUID()), it should get inlined to save gas:

Links to github files

UUPS.sol:L32

Instances

src/lib/proxy/UUPS.sol:32:    modifier notDelegated() {

Links to github files

UUPS.sol:L61

Instances where modifiers are used only once

src/lib/proxy/UUPS.sol:61:    function proxiableUUID() external view notDelegated returns (bytes32) {

---

3. Multiple address mappings can be combined into a single mapping of an address to a struct, where appropriate

Saves a storage slot for the mapping. Depending on the circumstances and sizes of types, can avoid a Gsset (20000 gas) per mapping combined. Reads and subsequent writes can also be cheaper when a function requires both values and they both fit in the same storage slot. Finally, if both fields are accessed in the same function, can save ~42 gas per access due to not having to recalculate the key's keccak256 hash (Gkeccak256 - 30 gas) and that calculation's associated stack operations.

There are 2 instances of this issue:

Links to github files

ERC721Votes.sol:L29 ERC721Votes.sol:L33 ERC721Votes.sol:L37

Instances 1

src/lib/token/ERC721Votes.sol:29:    mapping(address => address) internal delegation;
src/lib/token/ERC721Votes.sol:33:    mapping(address => uint256) internal numCheckpoints;
src/lib/token/ERC721Votes.sol:37:    mapping(address => mapping(uint256 => Checkpoint)) internal checkpoints;

Links to github files

ERC721.sol:L26 ERC721.sol:L30 ERC721.sol:L34 ERC721.sol:L38

Instances 2

src/lib/token/ERC721.sol:26:    mapping(uint256 => address) internal owners;
src/lib/token/ERC721.sol:30:    mapping(address => uint256) internal balances;
src/lib/token/ERC721.sol:34:    mapping(uint256 => address) internal tokenApprovals;
src/lib/token/ERC721.sol:38:    mapping(address => mapping(address => bool)) internal operatorApprovals;

---

4. Use abi.encodePacked() not abi.encode()

Changing abi.encode to abi.encodePacked can save gas. abi.encode pads extra null bytes at the end of the call data which is normally unnecessary. In general, abi.encodePacked is more gas-efficient.

Links to github files

MetadataRenderer.sol:L251 Manager.sol:L68 Manager.sol:L69 Manager.sol:L70 Manager.sol:L71 ERC721Votes.sol:L162 Governor.sol:L104 Governor.sol:L230 Treasury.sol:L107

Instances

src/token/metadata/MetadataRenderer.sol:251:        return uint256(keccak256(abi.encode(_tokenId, blockhash(block.number), block.coinbase, block.timestamp)));
src/manager/Manager.sol:68:        metadataHash = keccak256(abi.encodePacked(type(ERC1967Proxy).creationCode, abi.encode(_metadataImpl, "")));
src/manager/Manager.sol:69:        auctionHash = keccak256(abi.encodePacked(type(ERC1967Proxy).creationCode, abi.encode(_auctionImpl, "")));
src/manager/Manager.sol:70:        treasuryHash = keccak256(abi.encodePacked(type(ERC1967Proxy).creationCode, abi.encode(_treasuryImpl, "")));
src/manager/Manager.sol:71:        governorHash = keccak256(abi.encodePacked(type(ERC1967Proxy).creationCode, abi.encode(_governorImpl, "")));
src/lib/token/ERC721Votes.sol:162:                abi.encodePacked("\x19\x01", DOMAIN_SEPARATOR(), keccak256(abi.encode(DELEGATION_TYPEHASH, _from, _to, nonces[_from]++, _deadline)))
src/governance/governor/Governor.sol:104:        return keccak256(abi.encode(_targets, _values, _calldatas, _descriptionHash));
src/governance/governor/Governor.sol:230:                    keccak256(abi.encode(VOTE_TYPEHASH, _voter, _proposalId, _support, nonces[_voter]++, _deadline))
src/governance/treasury/Treasury.sol:107:        return keccak256(abi.encode(_targets, _values, _calldatas, _descriptionHash));

Recommended Mitigation Steps

You should change abi.encode to abi.encodePacked

---

5. Using private rather than public for constants / immutable, saves gas

Description

If needed, the values can be read from the verified contract source code, or if there are multiple values there can be a single getter function that returns a tuple of the values of all currently-public constants. Saves 3406-3606 gas in deployment gas due to the compiler not having to create non-payable getter functions for deployment calldata, not having to store the bytes of the value outside of where it’s used, and not adding another entry to the method ID table

Links to github files

Governor.sol:L27 Manager.sol:L25 Manager.sol:L28 Manager.sol:L31 Manager.sol:L34 Manager.sol:L37

Instances

src/governance/governor/Governor.sol:27:    bytes32 public constant VOTE_TYPEHASH = keccak256("Vote(address voter,uint256 proposalId,uint256 support,uint256 nonce,uint256 deadline)");
src/manager/Manager.sol:25:    address public immutable tokenImpl;
src/manager/Manager.sol:28:    address public immutable metadataImpl;
src/manager/Manager.sol:31:    address public immutable auctionImpl;
src/manager/Manager.sol:34:    address public immutable treasuryImpl;
src/manager/Manager.sol:37:    address public immutable governorImpl;

---