No matching declaration found after argument-dependent lookup

Question

Currently I'm trying to find a solution for this problem TypeError: Member "toTimestamp" is not available in contract DateTime outside of storage , and I decided to take another approach. I've inherited the DateTime contract and rewritten the method to be as follows:

function _incrementMonths(uint16 _months, uint _timestamp) internal returns (uint){
    uint16 year = getYear(_timestamp);
    uint16 month = getMonth(_timestamp);

    uint16 newMonth = month + _months;
    while(newMonth > 12){
        newMonth -= 12;
        year++;
    }

    // get new timestamp
    uint time = toTimestamp(
        year,
        newMonth,
        getDay(_timestamp),
        getHour(_timestamp),
        getMinute(_timestamp),
        getSecond(_timestamp)
    );
}

However now the compiler gives me this new error:

browser/Payroll.sol:326:21: TypeError: No matching declaration found after argument-dependent lookup.
        uint time = toTimestamp(
                    ^---------^

Again, the contract I'm referencing is found here: https://github.com/pipermerriam/ethereum-datetime/blob/master/contracts/DateTime.sol . The method I'm calling is found here https://github.com/pipermerriam/ethereum-datetime/blob/master/contracts/DateTime.sol#L165

I've been trying to debug this, but I don't see what is causing this error. What could be the cause?

---

Edit:

Please see the code in the IDE I've been working with https://ethereum.github.io/browser-solidity/#version=soljson-v0.4.17+commit.bdeb9e52.js&gist=03e5543f137d3ec464462cc190104de3

Answer 1

Your newMonth variable is a uint16. The toTimestamp function expects the month parameter to be a uint8.

uint time = toTimestamp(
    year,
    uint8(newMonth),   // <--- if you cast to uint8 the error goes away
    getDay(_timestamp),
    getHour(_timestamp),
    getMinute(_timestamp),
    getSecond(_timestamp)
);

Answer 2

For this error: TypeError: No matching declaration found after argument-dependent lookup:

It might happen because toTimestamp(... should has a public visibility.