Using empty functions instead of interfaces leaves contract error-prone.md

152 - Using empty functions instead of interfaces leaves contract error-prone

WithdrawalDelayerInterface is a contract meant to be an interface.

It contains functions with empty bodies instead of function signatures, which might lead to unexpected behavior.

A contract inheriting from WithdrawalDelayerInterface will not require an override of these functions and will not benefit from the compiler checks on its correct interface.

Recommendation:

Short term, use an interface instead of a contract in WithdrawalDelayerInterface.

This will make derived contracts follow the interface properly.

Long term, properly document the inheritance schema of the contracts.

Use Slither's inheritance-graph printer to review the inheritance.

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Slide Screenshot

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Slide Text

• ToB Audit Hermez Network Finding 11
• Undefined Behavior
• Empty Functions -> Interfaces -> Error-prone
• Use Interfaces

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References

• Youtube Reference
• ToB's Audit of Hermez Network

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