Gas Optimizations

[code423n4]

1. Variables: No need to explicitly initialize variables with default values

If a variable is not set/initialized, it is assumed to have the default value (0 for uint, false for bool, address(0) for address…). Explicitly initializing it with its default value is an anti-pattern and wastes gas.

Instances:

Project.sol:248
Project.sol:311
Project.sol:322
libraries/Tasks.sol:181
Community.sol:624
HomeFiProxy.sol:87

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

Recommendation:

I suggest removing explicit initializations for default values.

2.Use !=0 instead of > 0 for UINT

Instances

Project.sol:195
Community.sol:764

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

3. Custom Errors instead of Revert Strings to save Gas

Custom errors from Solidity 0.8.4 are cheaper than revert strings (cheaper deployment cost and runtime cost when the revert condition is met)

Starting from Solidity v0.8.4,there is a convenient and gas-efficient way to explain to users why an operation failed through the use of custom errors. Until now, you could already use strings to give more information about failures (e.g., revert("Insufficient funds.");),but they are rather expensive, especially when it comes to deploy cost, and it is difficult to use dynamic information in them.

Custom errors are defined using the error statement, which can be used inside and outside of contracts (including interfaces and libraries).

Instances:

HomeFi.sol

HomeFi.sol:73:        require(admin == _msgSender(), "HomeFi::!Admin");
HomeFi.sol:78:        require(_address != address(0), "HomeFi::0 address");
HomeFi.sol:84:        require(_oldAddress != _newAddress, "HomeFi::!Change");
HomeFi.sol:142:        require(!addrSet, "HomeFi::Set");
HomeFi.sol:191:        require(lenderFee != _newLenderFee, "HomeFi::!Change");

Project.sol

Project.sol:123:        require(!contractorConfirmed, "Project::GC accepted");
Project.sol:132:        require(_projectAddress == address(this), "Project::!projectAddress");
Project.sol:135:        require(_contractor != address(0), "Project::0 address");
Project.sol:150:        require(_msgSender() == builder, "Project::!B");
Project.sol:153:        require(contractor != address(0), "Project::0 address");
Project.sol:176:        require(_nonce == hashChangeNonce, "Project::!Nonce");
Project.sol:195:        require(_cost > 0, "Project::!value>0");
Project.sol:238:        require(_taskCount == taskCount, "Project::!taskCount");
Project.sol:241:        require(_projectAddress == address(this), "Project::!projectAddress");
Project.sol:245:        require(_length == _taskCosts.length, "Project::Lengths !match");
Project.sol:277:        require(_nonce == hashChangeNonce, "Project::!Nonce");
Project.sol:308:        require(_length == _scList.length, "Project::Lengths !match");
Project.sol:341:        require(_projectAddress == address(this), "Project::!Project");
Project.sol:369:        require(tasks[_taskID].getState() == 3, "Project::!Complete");
Project.sol:406:        require(_project == address(this), "Project::!projectAddress");
Project.sol:511:        require(_project == address(this), "Project::!projectAddress");
Project.sol:530:        require(getAlerts(_task)[2], "Project::!SCConfirmed");
Project.sol:753:        require(_sc != address(0), "Project::0 address");

Disputes.sol

Disputes.sol:39:        require(_address != address(0), "Disputes::0 address");
Disputes.sol:46:        require(homeFi.admin() == _msgSender(), "Disputes::!Admin");
Disputes.sol:52:        require(homeFi.isProjectExist(_msgSender()), "Disputes::!Project");
Disputes.sol:183:        require(_result, "Disputes::!Member");

DebtToken.sol:50

DebtToken.sol:50:        require(_communityContract != address(0), "DebtToken::0 address");

ProjectFactory.sol

ProjectFactory.sol:36:        require(_address != address(0), "PF::0 address");
ProjectFactory.sol:84:        require(_msgSender() == homeFi, "PF::!HomeFiContract");

libraries/Tasks.sol

libraries/Tasks.sol:44:        require(_self.state == TaskStatus.Inactive, "Task::active");
libraries/Tasks.sol:50:        require(_self.state == TaskStatus.Active, "Task::!Active");
libraries/Tasks.sol:124:        require(_self.subcontractor == _sc, "Task::!SC");

Community.sol

Community.sol:69:        require(_address != address(0), "Community::0 address");
Community.sol:75:        require(_msgSender() == homeFi.admin(), "Community::!admin");
Community.sol:241:        require(homeFi.isProjectExist(_project), "Community::Project !Exists");
Community.sol:248:        require(_community.isMember[_builder], "Community::!Member");
Community.sol:536:        require(_builder == _projectInstance.builder(), "Community::!Builder");
Community.sol:557:        require(!restrictedToAdmin, "Community::restricted");
Community.sol:568:        require(restrictedToAdmin, "Community::!restricted");
Community.sol:764:        require(_repayAmount > 0, "Community::!repay");
Community.sol:792:        require(_lentAndInterest >= _repayAmount, "Community::!Liquid");
HomeFiProxy.sol:41:       require(_address != address(0), "Proxy::0 address");

HomeFiProxy.sol

HomeFiProxy.sol:81:        require(_length == _implementations.length, "Proxy::Lengths !match");
HomeFiProxy.sol:133:        require(_length == _contractAddresses.length, "Proxy::Lengths !match");

4.++I COSTS LESS GAS THAN I++

Instances:

Project.sol:625
Project.sol:672
Community.sol:140

Project.sol:625:                    _loopCount++;
Project.sol:672:                    _loopCount++;
Community.sol:140:        communityCount++;