Contract always out of gas in Remix

Question

I am trying to test and deploy my contract using the latest ganache-cli v6.0.3 (ganache-core: 2.0.2) with Remix (http! version) on http://remix.ethereum.org. So, after starting ganache-cli without any extra parameters on standard port 8545, I connect on Remix via web3 Provider http://127.0.0.1:8545 and my accounts show up, as displayed by Ganache.

This is the contract I want to deploy:

pragma solidity ^0.4.20;

contract Test {

    uint[4] public arr; // [0,0,0,0]
    event TestLog(string logmessage);

    function Test() public {
        arr[0] = 1; // [1,0,0,0]
    }

    function checkArray() public {
        if(arr[0] == 1) { // arr == [1,?,?,?]
            arr[1] = 1;
            arr[0] = 0; // switch values [0,1,0,0]
        }
        TestLog("some log");
    }

}

It works fine with the in-built Javascript VM in Remix: [vm] from:0xca3...a733c, to:Test.checkArray() 0x692...77b3a, value:0 wei, data:0x7b3...f7296, 1 logs, hash:0xa6f...87209

If i try to run the checkArray function in Remix connected to ganache via web3 Provider, I get an transact to Test.checkArray errored: VM Exception while processing transaction: out of gas error.

What am I doing wrong here? Bumping up gasLimit with ganache-cli -l 5000000did not help, as well as even higher values and a follow up test with a very small gasPrice and high gas limit. Is it a Remix problem setting wrong gas limits on the Remix website when building the transaction? I also tried it on a private geth node with the same result: out of gas...

Any help gladly appreciated!

Answer 1

This seems to be a testrpc/ganache bug. The line making trouble is setting respectively resetting the array value at position 0 to zero arr[0] = 0;.

I used Rinkeby with the same contract and it works as initially expected. You may test it here: https://rinkeby.etherscan.io/address/0x78aC7667BdeDC3b1CdF43611AdF7a88e05b600F5

As this is some very basic functionality, I'm left to say: what the fuck?

Answer 2

In my opinion, setting arr[0] is incorrect because that element doesn't exist. It is/was always walking off the end of the array. Use arr.push(1) to extend the length of the array.

Hope it helps.