Suggested improvement on your token contracts

General
1

Hi,
I have a use case to replace the way balances are calculated. In fact to replace _balances mapping and some logic with my own.
Found out that I couldn’t do it without modifying your code for ERC777.sol (and I guess ERC20.sol if I need that as well).
The required changes to your contract were minimal. The transferFrom function is fine because it has a _move function that I can override. Unfortunately, this isn’t the case for your _burn and _mint functions. Here’s my amendment to your contract for _burn

    function _burn(
        address from,
        uint256 amount,
        bytes memory data,
        bytes memory operatorData
    ) internal virtual {
.
.

        _beforeTokenTransfer(operator, from, address(0), amount);

        _burnState(from, amount);

        emit Burned(operator, from, amount, data, operatorData);
.
.
    }

    function _burnState(
        address from,
        uint256 amount
        )
        internal virtual {
        // Update state variables
        uint256 fromBalance = _balances[from];
        require(fromBalance >= amount, "ERC777: burn amount exceeds balance");
        unchecked {
            _balances[from] = fromBalance - amount;
        }
        _totalSupply -= amount;           
    }

I did something the same for _mint.

So these minor changes, might be useful for others as well? And allow your contracts to be used without modification.

Jules