Missing initializer for ReentrancyGuard in v5.5.0

[aviggiano]

In contracts v5.5.0 ReentrancyGuardUpgradeable was deprecated as part of #5944 in favor of a stateless ReentrancyGuard.

The issue is that the non-upgradeable version initializes the storage value on the constructor, which is a problem for proxy-based contracts.

If I understand correctly, integrators must manually call _reentrancyGuardStorageSlot().getUint256Slot().value = NOT_ENTERED; on the initializer function.

A better solution would be to still provide an initializer for proxy contracts.

[ernestognw]

Hey @aviggiano, thanks for submitting the issue. I also had the same feeling that the change was breaking and expressed it in this comment, but as @Amxx pointed out, the contract would work just fine even if it's not initialized since the first use of the nonReentrant modifier will set the value correctly to ENTERED and then reset it to NOT_ENTERED.

You're essentially right that integrators could manually do _reentrancyGuardStorageSlot().getUint256Slot().value = NOT_ENTERED; but that's not strictly required and there is no negative externality from not initializing the value.

Is there any particular concern we should consider?

[aviggiano]

Hey

Thanks for responding. I agree that this shouldn't be a concern, but I've always called __ReentrancyGuard_init() on the initializer regardless, for the sake of consistency and to defensively make contracts future-proof. If this wasn't necessary, we could argue that the constructor shouldn't set the value to NOT_ENTERED.

Anyway, not a big deal