New Base Contract in Upgradeable Contract

Support Upgrades
1

I have upgradeable contracts (ERC20/ERC721). I would like to add a new base contract ERC2771Context.
Is that upgrade safe?

2

Hi, the problem is that by adding a new base class, you're going to have a storage layout incompatibility. But if you are using the OZ contracts, we apply a storage variable called gap at the end of the storage variables to keep the ability to add new storage variables.

Maybe this question answer might be of help: Updating inheritance of contract during contract upgrade - #2 by nyg

3

Thank you very much indeed for your advice, @JulissaDantes !