supernova - Confusion in gap size

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supernova

low

Confusion in gap size

Summary

According to the comments

Reserve extra slots in the storage layout for future upgrades.
     *         A gap size of 41 was chosen here, so that the first slot used in a child contract
     *         would be a multiple of 50.

Vulnerability Detail

But actually gap is provided for 42 instead of 41 mentioned above . This can lead to presumptions on the minds of the dev that the first slot of the child contract is a multiple of 50 , when it is not .

Impact

Code Snippet

https://github.com/sherlock-audit/2023-01-optimism/blob/main/optimism/packages/contracts-bedrock/contracts/universal/CrossDomainMessenger.sol#L132-L137

Tool used

Manual Review

Recommendation

Clear the collision in the comments and the actual code .