Cannot mint ERC223 token

Question

Hello I have a simple implementation for a ERC223 Token. I use this repository: ERC223-token-standard

Here is my contract Code:

pragma solidity ^0.5.8;

import "./ERC223-token-standard-development/token/ERC223/ERC223Burnable.sol";
import "./ERC223-token-standard-development/token/ERC223/ERC223Mintable.sol";

contract MyToken is ERC223Burnable, ERC223Mintable{
}

The first strange Thing is that I get this warning when compiling:

Warning: Function state mutability can be restricted to view
    function mint(address account, uint256 amount) public onlyMinter returns (bool) {
    ^ (Relevant source part starts here and spans across multiple lines).

I think this is weird because to my understanding it changes the state of the contract and should not be a view function

However after creating my contract and using the mint function the totalSupply is still 0 even though isMinter(myaddr) returns true. I thought that I was just doing something wrong in the truffle testfile but after I pushed my code into Remix I still get the same warning and the total supply is still 0.

I hope you can help me with this issue.

Answer 1

The implementation of mint is wrong

function mint(address account, uint256 amount) public onlyMinter returns (bool) {
    _totalSupply.add(amount);
    balances[msg.sender].add(amount);
    return true;
}

It should be

function mint(address account, uint256 amount) public onlyMinter returns (bool) {
    bytes memory empty = hex"00000000";
    _totalSupply = _totalSupply.add(amount);
    balances[msg.sender] = balances[msg.sender].add(amount);
    emit Transfer(address(0x0), msg.sender, amount, empty);
    return true;
}