Rigor Protocol contest - apostle0x01's results

Issues found

[G-01] Don't Initialize Variables with Default Value

Explicitly initializing a variable with it's default value costs unnecesary gas.

Findings:

contracts/Community.sol::624 => for (uint256 i = 0; i < _communities[_communityID].memberCount; i++) {
contracts/HomeFiProxy.sol::87 => for (uint256 i = 0; i < _length; i++) {
contracts/HomeFiProxy.sol::136 => for (uint256 i = 0; i < _length; i++) {
contracts/Project.sol::248 => for (uint256 i = 0; i < _length; i++) {
contracts/Project.sol::311 => for (uint256 i = 0; i < _length; i++) {
contracts/Project.sol::322 => for (uint256 i = 0; i < _length; i++) {
contracts/libraries/Tasks.sol::181 => for (uint256 i = 0; i < _length; i++) _alerts[i] = _self.alerts[i];

[G-02] Cache Array Length Outside of Loop

Caching the array length outside a loop saves reading it on each iteration, as long as the array's length is not changed during the loop.

Findings:

./contracts/Project.sol:603:            for (; i < _changeOrderedTask.length; i++) {

[G-03] Use != 0 instead of > 0 for Unsigned Integer Comparison

When dealing with unsigned integer types, comparisons with != 0 are cheaper then with > 0.

Findings:

contracts/Community.sol::764 => require(_repayAmount > 0, "Community::!repay");
contracts/Project.sol::195 => require(_cost > 0, "Project::!value>0");

[G-04] Increments can be unchecked

Impact

In Solidity 0.8+, there's a default overflow check on unsigned integers. It's possible to uncheck this in for-loops and save some gas at each iteration, but at the cost of some code readability, as this uncheck cannot be made inline.

Instances include:

./contracts/HomeFiProxy.sol:87:        for (uint256 i = 0; i < _length; i++) {
./contracts/HomeFiProxy.sol:136:        for (uint256 i = 0; i < _length; i++) {
./contracts/Project.sol:248:        for (uint256 i = 0; i < _length; i++) {
./contracts/Project.sol:311:        for (uint256 i = 0; i < _length; i++) {
./contracts/Project.sol:322:        for (uint256 i = 0; i < _length; i++) {
./contracts/Project.sol:603:            for (; i < _changeOrderedTask.length; i++) {
./contracts/Community.sol:624:        for (uint256 i = 0; i < _communities[_communityID].memberCount; i++) {
./contracts/libraries/Tasks.sol:181:        for (uint256 i = 0; i < _length; i++)

The code would go from:

for (uint256 i = 0; i < _length; i++) {
 // ...  
}  

to:

for (uint256 i = 0; i < _length;) {
 // ...  
 unchecked { ++i; }  
}  

The risk of overflow is inexistant for a uint256 here.