remix compiler warning infinite gas requirement

Question

I'm trying to deploy a trivial faucet program which compiles OK with remix but I get the following error. "Gas requirement of function Faucet.withdraw(uint256) high: infinite. " This means that while it compiles I cannot deploy it to my Ganache blockchain. I understand the concept of gas for a function but I cannot see what is potentially infinite here: I have put a tiny limit on any withdrawal amount.

Could someone please explain?

pragma solidity >=0.5.0;

contract Faucet {

    function withdraw(uint256 withdraw_amount) public   {    
        require(withdraw_amount <= 2000000);
        msg.sender.transfer(withdraw_amount);
        }

    // Accept any incoming amount
    function () external payable {}
}

Answer 1

Gas requirement of function Faucet.withdraw(uint256) high: infinite.

Thisis a misleading warning caused by the require(). It can be safely ignored.

This means that while it compiles I cannot deploy it to my Ganache blockchain

Not true. You can deploy it.

pragma solidity >=0.5.0;

In my opinion, this is bad form except in librarys and inheritable contracts. You do indeed have a problem with 0.6.x and above because the fallback syntax is changed from an unnamed function to an explicitly named fallback() function.

One cannot know what breaking changes will be introduced in the future, so top-level contracts (to deploy) should indicate precisely what compiler to use. One can safely use ^ and >= for inherited modules that will not be deployed on their own.

I did not know what you used because it is ambiguous. However, I can see that it compiles and deploys with 0.5.16, and it does not with 0.6.x so ...

pragma solidity 0.5.16;

contract Faucet {

    function withdraw(uint256 withdraw_amount) public   {    
        require(withdraw_amount <= 2000000);
        msg.sender.transfer(withdraw_amount);
        }

    // Accept any incoming amount
    function () external payable {}
}

Hope it helps.