Nouns Builder contest - Chandr's results

PREFIX INCREMENTS

IMPACT Prefix increments are cheaper than postfix increments.

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/token/Token.sol#L91 uint256 founderId = settings.numFounders++;

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/governance/governor/Governor.sol#L230 keccak256(abi.encode(VOTE_TYPEHASH, _voter, _proposalId, _support, nonces[_voter]++, _deadline))

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/lib/token/ERC721Votes.sol#L207 uint256 nCheckpoints = numCheckpoints[_from]++;

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/lib/token/ERC721Votes.sol#L222 uint256 nCheckpoints = numCheckpoints[_to]++;

Mitigation: replace foo++ to ++foo

DEFAULT VALUE INITIALIZATION

IMPACT If a variable is not set/initialized, it is assumed to have the default value (0, false, 0x0 etc depending on the data type). Explicitly initializing it with its default value is an anti-pattern and wastes gas.

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/token/metadata/MetadataRenderer.sol#L119 for (uint256 i = 0; i < numNewProperties; ++i) {

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/token/metadata/MetadataRenderer.sol#L133 for (uint256 i = 0; i < numNewItems; ++i) {

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/token/metadata/MetadataRenderer.sol#L189 for (uint256 i = 0; i < numProperties; ++i) {

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/token/metadata/MetadataRenderer.sol#L229 for (uint256 i = 0; i < numProperties; ++i) {

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/governance/treasury/Treasury.sol#L162 for (uint256 i = 0; i < numTargets; ++i) {

Mitigation: Remove explicit value initialization.

COMPARISON OPERATORS

IMPACT In the EVM, there is no opcode for >= or <=. When using greater than or equal, two operations are performed: > and =. Using strict comparison operators hence saves gas.

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/token/metadata/MetadataRenderer.sol#L197 seed >>= 16;

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/auction/Auction.sol#L98 if (block.timestamp >= _auction.endTime) revert AUCTION_OVER();

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/governance/treasury/Treasury.sol#L89 return timestamps[_proposalId] != 0 && block.timestamp >= timestamps[_proposalId];

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/lib/token/ERC721Votes.sol#L61 if (_timestamp >= block.timestamp) revert INVALID_TIMESTAMP();

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/lib/token/ERC721Votes.sol#L78 if (accountCheckpoints[lastCheckpoint].timestamp <= _timestamp) return accountCheckpoints[lastCheckpoint].votes;

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/lib/utils/Initializable.sol#L56 if (_initializing || _initialized >= _version) revert ALREADY_INITIALIZED();

Mitigation: Replace <= with <, and >= with >. Do not forget to increment/decrement the compared variable

COMPARISON WITH ZERO

IMPACT >0 is less gas efficient than !0 if you enable the optimizer at 10k AND you’re in a require statement. Detailed explanation with the opcodes here

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/lib/token/ERC721Votes.sol#L203 if (_from != _to && _amount > 0) {

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/lib/proxy/ERC1967Upgrade.sol#L61 if (_data.length > 0 || _forceCall) {

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/lib/utils/Address.sol#L50 if (_returndata.length > 0) {

Mitigation: Replace >0 with !0

Increment/decrement operations

IMPACT X = X + Y IS CHEAPER THAN X += Y X = X - Y IS CHEAPER THAN X -= Y

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/token/Token.sol#L88 if ((totalOwnership += uint8(founderPct)) > 100) revert INVALID_FOUNDER_OWNERSHIP();

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/token/Token.sol#L118 (baseTokenId += schedule) % 100;

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/token/metadata/MetadataRenderer.sol#L140 _propertyId += numStoredProperties;

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/governance/governor/Governor.sol#L280 proposal.againstVotes += uint32(weight);

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/governance/governor/Governor.sol#L285 proposal.forVotes += uint32(weight);

Instance: https://github.com/code-423n4/2022-09-nouns-builder/tree/main/src/governance/governor/Governor.sol#L290 proposal.abstainVotes += uint32(weight);

Mitigation: X += Y replace with X = X + Y X -= Y replace with X = X - Y