[CODE QUALITY] Unused Storage Variable in RollupCore.sol

[evmparser]

Summary

The RollupCore.sol contract declares a private storage variable gap that is never used, leading to confusing code and wasted deployment gas.

Severity

LOW - Code quality issue, no direct security impact

Location

• File: l1-contracts/src/core/RollupCore.sol
• Line: Approximately line 283

Description

The contract declares an unused storage variable:

/**
 * @dev Storage gap to ensure checkBlob is in its own storage slot
 */
uint256 private gap = 0; // This variable is declared but never read or written to.

Issues

1. Unused Variable: The gap variable is never accessed anywhere in the contract
2. Unclear Intent: The comment suggests it's for storage layout management, but a single uint256 doesn't create a meaningful gap
3. Gas Waste: Initializing this variable costs gas on deployment with no benefit
4. Code Smell: May indicate incomplete implementation of an upgradeability pattern

Impact

• Minor gas waste on deployment
• Code confusion for developers and auditors
• Potential misunderstanding of storage layout intentions

Recommendation

Option 1: If storage gap is needed for upgradeability, implement it properly:

// Reserve 50 storage slots for future upgrades
uint256[50] private __gap;

Option 2: If not needed, remove the variable entirely:

// Remove the unused gap variable and its comment

Option 3: If it's specifically for checkBlob alignment, add a comment explaining why and ensure it's actually achieving the intended layout.

Additional Context

Proper storage gaps are typically implemented as arrays (e.g., uint256[50]) in upgradeable contracts following the OpenZeppelin pattern. A single unused variable doesn't serve this purpose effectively.