Call to super.owner().transfer(msg.value) giving errors

Question

I have a contract that inherits from Open Zeppelin's Ownable contract. There is a method payFees() in my contract that is expected to transfer funds to the owner of the contract. The definition of payFees is as follows

function payFees() public payable {
        require(students.has(msg.sender), "DOES NOT HAVE STUDENT ROLE");
        if(this.areFeesEnough(msg.value))
        {
            super.owner().transfer(msg.value);
            studentFees[msg.sender] = true;
        }

    }

I expect that a call to super.owner() returns the contract owner given that owner() is a public view function in the parent Ownable contract that returns the owner. Unfortunately, the code fails with the error.

             TypeError: Member "transfer" not found or not visible after argument-dependent lookup in address.
            super.owner().transfer(msg.value);

Any help is appreciated.Thank you.

Answer 1

Assuming the Ownable contract you're using is similar to https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/contracts/ownership/Ownable.sol, the issue is that owner() returns an address, but starting in Solidity 0.5, you can only transfer ether to an address payable.

You can convert by casting through uint160 first, something like this:

address(uint160(_owner)).transfer(msg.value);

Note that you can just use _owner directly or just call owner(). No need to call super.owner() unless you've overridden owner in your contract and need to make sure to call the parent contract.