Tuple assignments done element wise

[hajduakos]

Currently, tuple assignments are performed element-wise in a left-to-right order, which gives an incorrect result. Example:

pragma solidity >=0.5.0;

contract Swap {
    uint a;
    uint b;

    function() external payable {
        uint x = 1;
        uint y = 2;
        (x, y) = (y, x);
        assert(x == 2);
        assert(y == 1);

        a = 1;
        b = 2;
        (a, b) = (b, a);
        assert(a == 2);
        assert(b == 1);
    }
}

The assertions should hold in this case, but fail in solc-verify.

[hajduakos]

Fixed in 9185d2d and b4e41d4