Nouns Builder contest - WatchDogs's results

[Gas - 01] >= cost more than >

A single > operator costs less gas as compared to the >= operator.

Instances of this issue :

• Auction.sol L98
• Treasury.sol L89
• ERC721Votes.sol L61

[G - 02] Add payable to functions that won't receive ETH

OnlyOwner functions cannot be called by normal users and will not receive ETH by mistake. To save gas, these functions can be made payable.

Instances of this issue :

• Auction.sol L244 L263 L307 L315 L323 L331
• Governor.sol L564 L572 L580 L588 L596 L605
• Treasury.sol L180

[Gas - 03] Using bool s for storage incurs overhead

It costs more to declare storage variables as bools than as uint256.

Instances of this issue :

• GovernorStorageV1.sol L19
• ERC721.sol L38
• ManagerStorageV1.sol L10
• Auction.sol L136 L349
• ERC1967Upgrade.sol L57

[Gas - 04] For array parameters in functions, it is recommended to use calldata over memory

When an external function with a memory array is called, the abi.decode() step has to use a for-loop to copy each index of the calldata to the memory index. Each iteration of this for-loop costs at least 60 gas (i.e. 60 * <mem_array>.length).

Change the following from memory to calldata :

• Governor.sol L98 L116
• IGovernor.sol L134 L146 L195
• Treasury.sol L258
• ERC1967Upgrade.sol L35 L56

[Gas - 05] No need to explicitly initialize variables with default values

Declaration of variables with default values cost gas. such as

uint256 a = 0; change to → uint256 a;

Instances of this issue :

• Treasury.sol L162
• MetadataRenderer.sol L119 L133 L189 L229

[Gas - 06] Use Shift Right/Left instead of Division/Multiplication if possible

Change the following from:

uint256 b = a / 2; → uint256 b = a >> 1;

• ERC721Votes.sol L95

[Gas - 07] Use ++x instead of x++

Use Prefix increment rather than Postfix increment, it saves gas.

Instances of this issue :

• Token.sol L154 L91
• Governor.sol L230

[Gas - 08] <x> += <y> costs more gas than <x> = <x> + <y>

Using the addition operator instead of plus-equals saves gas.

Instances of this issue :

• Governor.sol L280 L285 L290
• MetadataRenderer.sol L140

[Gas - 09] Splitting if() statements that use ||/&& saves gas

Whenever the conditional statement uses the ||/&& operator to revert the same error, it‘s better to split the if statement so that the first condition is executed directly rather than having both conditions executed.

Instances of this issue :

• Governor.sol L239 L363
• ERC721Votes.sol L170

[Gas - 10] Internal functions called once can be inlined to save gas

When internal functions are called once in the contract, it is better to inline them rather than declaring because function declarations are expensive.

Instances of this issue :

• ERC1967Upgrade.sol L68

[Gas - 11] Use IsZero EVM opcode for Zero address / Zero value checks

Since there is a direct opcode for this operation, implementing this saves gas.

Instances of this issue :

• Auction.sol L104 L175 L184 L189 L248
• Governor.sol L70 L71 L135
• Treasury.sol L48

[Gas - 12] Empty block should be removed or emit something

The code should be refactored such that they no longer exist, or the block should do something useful, such as emitting an event or reverting. If the contract is meant to be extended, the contract should be abstract and the function signatures are added without any default implementation. If the block is an empty if-statement block to avoid doing subsequent checks in the else-if/else conditions, the else-if/else conditions should be nested under the negation of the if-statement, because they involve different classes of checks, which may lead to the introduction of errors when the code is later modified (if(x){}else if(y){...}else{...} =>  if(!x){if(y){...}else{...}})

Instances of this issue :

• Manager.sol L209
• Treasury.sol L269