Avoid unused variables

Unusued variables should not be defined on contracts, either as state variables or as local variables. This corresponds to SWC-103.

Apply with the Grit CLI

grit apply NoUnusedVariables

State Variable

BEFORE

pragma solidity >=0.5.0;
pragma experimental ABIEncoderV2;

import "./base.sol";

contract DerivedA is Base {
    // i is not used in the current contract
    A i = A(1);

    int internal j = 500;

    function assign3(A memory x) public returns (uint) {
        return g[1] + x.a + uint(j);
    }
}

AFTER

pragma solidity >=0.5.0;
pragma experimental ABIEncoderV2;

import "./base.sol";

contract DerivedA is Base {
    // i is not used in the current contract
    A i = A(1);

    int internal j = 500;

    function assign3(A memory x) public returns (uint) {
        return g[1] + x.a + uint(j);
    }
}

Local Variable

BEFORE

pragma solidity ^0.5.0;

contract UnusedVariables {
    int a = 1;

    // x is not accessed
    function neverAccessed(int test) public pure returns (int) {
        int z = 10;

        if (test > z) {
            // x is not used
            int x = test - z;

            return test - z;
        }

        return z;
    }
}

AFTER

pragma solidity ^0.5.0;

contract UnusedVariables {
    int a = 1;

    // x is not accessed
    function neverAccessed(int test) public pure returns (int) {
        int z = 10;

        if (test > z) {
            // x is not used
            int x = test - z;

            return test - z;
        }

        return z;
    }
}