Gas: Reorder conditions in claimGovernanceTribute

[code423n4]

Handle

cmichel

Vulnerability details

The FSD.claimGovernanceTribute function first performs the expensive getPriorConvictionScore instead of the cheap isGovernance[msg.sender] check.

function claimGovernanceTribute(uint256 num) external {
    require(
        governanceThreshold <=
            getPriorConvictionScore(
                msg.sender,
                governanceTributes[num].blockNumber
            ) &&
            // @audit gas: rearrange this to be first for short circuiting
            isGovernance[msg.sender],
        "FSD::claimGovernanceTribute: Not a governance member"
    );
    _claimGovernanceTribute(num);
}

Reordering the conditions to first do the cheap governance check would allow this function to short-circuit if the user is not a governor, which will save gas on average.
The last assignment membership[msg.sender] = user; is not required.

[pauliax]

Valid optimization.