Linearization of inheritance graph impossible as of v1.11.0

[mswezey23]

🎉 Description

• [X ] 🐛 This is a bug report.

💻 Environment

OZ version: v1.10.0 and v1.11.0
Network: Ganache
Tooling: Truffle

📝 Details

TypeError: Linearization of inheritance graph impossible as of v1.10.0
The contracts: WhitelistedCrowdsale & FinalizableCrowdsale with Ownable being the cause.

🔢 Code To Reproduce Issue [ Good To Have ]

CustomCrowdsale is CappedCrowdsale, MintedCrowdsale, WhitelistedCrowdsale, FinalizableCrowdsale

👍 Other Information

This was working okay in v1.9.0. WhitelistedCrowdsale was update in v1.10.0 which introduced this 🐛.

[frangio]

Thanks for reporting @mswezey23! I was able to reproduce this in 1.11.0, but not in 1.10.0. My understanding is that the bug was introduced in #981, which was only included in 1.11.0.

I think the problem is caused by this line:
https://github.com/OpenZeppelin/openzeppelin-solidity/blob/73be06412fdeb0453c11fa708d4e211947569ec3/contracts/crowdsale/distribution/FinalizableCrowdsale.sol#L13

Swapping Ownable and TimedCrowdsale makes linearization possible.

It should've been like that from the beginning because of the rule that "most base-like" goes to the left of the inheritance list.

[mswezey23]

Ah, that could have been my mix up. Yarn and I were having some issues & we had to duke it out. Apparently manually updating the versions in the package.json file to downgrade the OZ version doesn't work. It keeps the latest in the yarn.lock file. Had to run the commands yarn remove ... and yarn add ... for a successful downgraded version... back to topic now.

Thanks, @frangio, for the additional insight and confirming the bug!

Glad the fix is easy as swapping the order 😎