Openzeppelin-contracts: Warnings for this.balance in contracts since 0.4.21

[shyheim103]

🎉 Description

wallet.transfer(this.balance); throws a warning: "Using contract member "balance" inherited from the address type is deprecated. Convert the contract to "address" type to access the member."

• [x] 🐛 This is a bug report.
• [ ] 📈 This is a feature request.

[shrugs]

The solution to this is probably to change line https://github.com/OpenZeppelin/zeppelin-solidity/blob/master/contracts/crowdsale/distribution/utils/RefundVault.sol#L47 to

wallet.transfer(address(this).balance);

Because .balance is a property of the address type, not the Contract type.

[shrugs]

@shyheim103 which compiler version are you using?

[frangio]

This warning is showing up since Solidity 0.4.21. It comes up in Travis after #876.

[shyheim103]

I solved it the way @Shrugs mentioned. It wasn't a problem for me, I was just informing the community about it in case someone else runs across it. Easy fix. But I was using compiler version 0.4.18 or 21