Bad address of function type

[charles-liu]

The address of a function type loses the first byte after ABI encoding.

pragma soliditypp ^0.8.0;

contract A {
    function add(uint a, uint b, function(uint) external callback) external {
        if (callback.address != address(0)) {
            // the callback.address is broken here (lose the first byte)
            callback(a + b);
        }
    }
}

contract B {
    A contractA;
    uint public data;

    constructor (address addr) {
        contractA = A(addr);
    }

    function test() external {
        // the following assert is ok
        require(this.callback_onAdd.address == address(this));
        contractA.add(1, 2, this.callback_onAdd);
    }

    function callback_onAdd(uint result) external {
        require(msg.sender == address(contractA));
        data = result;
    }
}

Cause: It's an address format issue, a Vite addresse has 168 bits rather than 160 bits like Ethereum.