False positive on external-function

[mrice32]

When a function is declared by and called within the base class and overridden by the derived class, slither generates an error on the derived class saying that the function could be made external because the derived class doesn't call the function internally. However, the internal linkage is being used by the base class, and Solidity doesn't allow a derived class to change the visibility of a function when overriding it. Feel free to close if you think this detector is working as intended. I've built a minimal example that shows the false positive.

/*
  Test
*/
pragma solidity ^0.5.0;


contract Base {
    // Meant to be customized/overridden by derived classes.
    function abstractFunction() public;
    function callAbstract() external {
        abstractFunction();
    }
}


contract Derived is Base {
    function abstractFunction() public {
        // Some custom functionality.
    }
}

[montyly]

Thanks @mrice32 for the report! It's a valid issue.

We are going to update the detector to avoid this FP