56462 sc insight unused mapping causes unnecessary storage gas consumption

Submitted on Oct 16th 2025 at 10:13:25 UTC by @Purpledragon for Audit Comp | Alchemix V3

• Report ID: #56462

• Report Type: Smart Contract

• Report severity: Insight

• Target: https://github.com/alchemix-finance/v3-poc/blob/immunefi_audit/src/AlchemistV3.sol

• Impacts:

Description

Summary:

The mapping _redemptions and struct RedemptioInfo are declared in AlchemistV3.sol and IAlchemistV3.sol correspondingly.

AlchemistV3.sol:Line140
mapping(uint256 => RedemptionInfo) private _redemptions; 

IAlchemistV3.sol:Line64
struct RedemptionInfo {
    uint256 earmarked;
    uint256 debt;
    uint256 earmarkWeight;
}

However, both the mapping and struct is never used anywhere in the contract logic. There are no reads, writes, or references to _redemptions and RedemptionInfo in the code.

Impact

• Unnecessary Storage Allocation: Declaring a mapping in contract storage reserves a slot in the contract's storage layout, which increases deployment gas costs.

• Wasted Gas: Although mappings themselves do not consume gas until written to, their presence in the storage layout still increases the contract's complexity and deployment cost.

Recommendation

Remove the unused _redemptions mapping and RedemptionInfo from the contract to optimize storage usage and reduce deployment gas costs. This will also improve code clarity and maintainability.

Proof of Concept

Proof of Concept

For Mapping:

1. Navigate to the AlchemistV3.sol contract

2. Scroll to the Line64 to observe the _redemptions mapping is declared, but not used else where in the codebase i.e no read or write operation is performed on this mapping.

For Struct:

1. Navigate to the IAlchemistV3.sol contract

2. Scroll to the Line140 to observe the RedemptionInfo struct is declared, but not used else where in the codebase i.e no read or write operation is performed on this struct.