Unused Code Elements
Description
Unused imports, errors, and other code elements should be removed to improve code cleanliness, reduce contract size, and eliminate potential confusion for developers and auditors.
The contract contains unused import IERC20 and unused error RaiseBoxFaucet_CannotClaimAnymoreFaucetToday which indicate incomplete code cleanup and create confusion about intended functionality while unnecessarily increasing deployment costs.
@> import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
@> error RaiseBoxFaucet_CannotClaimAnymoreFaucetToday();
Risk
Likelihood: High
-
Unused code persists indefinitely unless actively identified and removed during development
-
Code reviews waste time analyzing unused elements trying to understand their purpose
-
Developers may make incorrect assumptions about intended functionality based on unused code
Impact: Low
-
Increased contract deployment costs due to larger bytecode from unused imports
-
Developer confusion when trying to understand code relationships and intended functionality
-
Reduced code quality and maintainability due to clutter and misleading elements
-
Potential false assumptions about security controls or error handling capabilities
Proof of Concept
contract UnusedCodeAnalysis {
function analyzeUnusedElements() external pure returns (
string[] memory impacts,
uint256 estimatedGasWaste,
string memory maintenanceCost
) {
impacts = new string[](5);
impacts[0] = "IERC20 import adds unnecessary bytecode to deployment";
impacts[1] = "Unused error suggests daily limit functionality that doesn't exist";
impacts[2] = "Code reviewers waste time analyzing unused elements";
impacts[3] = "Developers may assume unused error provides protection";
impacts[4] = "Contract appears larger and more complex than it actually is";
estimatedGasWaste = 1000;
maintenanceCost = "High - developers must investigate each unused element";
return (impacts, estimatedGasWaste, maintenanceCost);
}
function showConfusionScenarios() external pure returns (
string memory scenario1,
string memory scenario2,
string memory scenario3
) {
scenario1 = "Developer sees unused IERC20 import, assumes contract interfaces with other tokens";
scenario2 = "Security reviewer sees unused error, assumes daily limit protection exists";
scenario3 = "Integrator references unused error in documentation, creating confusion";
return (scenario1, scenario2, scenario3);
}
function showCleanupBenefits() external pure returns (
string[] memory benefits
) {
benefits = new string[](4);
benefits[0] = "Smaller deployment size reduces gas costs";
benefits[1] = "Cleaner code is easier to understand and review";
benefits[2] = "No misleading elements that suggest unimplemented features";
benefits[3] = "Reduced maintenance overhead and developer confusion";
return benefits;
}
}
Real confusion scenario:
Security auditor reviews contract
Sees "RaiseBoxFaucet_CannotClaimAnymoreFaucetToday" error
Assumes this protects against excessive daily claims
Spends time looking for where this error is used
Discovers it's never used, wasting audit time
Questions whether important protection is missing
Has to verify that other mechanisms provide protection
Unused error created false security assumptions
Recommended Mitigation
The mitigation removes all unused code elements and either implements their intended functionality or ensures proper cleanup, resulting in cleaner, more maintainable code with accurate functionality representation.
// Remove unused import
- import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
import {ERC20} from "@openzeppelin/contracts/token/ERC20/ERC20.sol";
import {Ownable} from "@openzeppelin/contracts/access/Ownable.sol";
// Either remove unused error or implement its intended functionality
- error RaiseBoxFaucet_CannotClaimAnymoreFaucetToday();
// Option 1: Remove if not needed
// (Just delete the line above)
// Option 2: Implement the error if daily limit protection was intended
+ function claimFaucetTokens() external nonReentrant whenNotPaused {
+ // ... existing checks ...
+
+ if (dailyClaimCount >= dailyClaimLimit) {
+ revert RaiseBoxFaucet_DailyClaimLimitReached(); // Use existing error
+ // OR revert RaiseBoxFaucet_CannotClaimAnymoreFaucetToday(); // Use the unused error
+ }
+
+ // ... rest of function ...
+ }
// Add systematic approach to prevent unused code accumulation
+ /**
+ * @dev Code Cleanup Checklist:
+ * ✅ All imports are used in the contract
+ * ✅ All errors are referenced in require/revert statements
+ * ✅ All events are emitted somewhere in the contract
+ * ✅ All functions are either called or intended as external interface
+ * ✅ All state variables are read/written by contract logic
+ */
// Optional: Add linting rules to catch unused elements automatically
// In .solhint.json or similar:
+ {
+ "rules": {
+ "no-unused-import": "error",
+ "no-unused-vars": "error",
+ "reason-string": "warn"
+ }
+ }
// If IERC20 functionality was intended, implement it properly:
// Option: Add token interaction capabilities if needed
+ function withdrawERC20Token(address token, uint256 amount) external onlyOwner {
+ require(token != address(this), "Cannot withdraw faucet tokens this way");
+ IERC20(token).transfer(msg.sender, amount);
+ emit ERC20TokenWithdrawn(token, amount);
+ }
+
+ event ERC20TokenWithdrawn(address indexed token, uint256 amount);
+
+ // Re-add import only if actually implementing token interactions:
+ // import {IERC20} from "@openzeppelin/contracts/token/ERC20/IERC20.sol";
// Document cleanup in code comments
+ /**
+ * @notice This contract has been cleaned of unused code elements
+ * @dev All imports, errors, events, and functions serve a purpose
+ * @dev Regular cleanup prevents accumulation of dead code
+ */
