contract Test {
    struct S {
        uint8 a;
        mapping(uint256 => uint256) b;
        uint8 c;
    }
    S s;

    function f() public returns (uint256) {
        S memory x;
        if (x.a != 0 || x.c != 0) return 1;
        x.a = 4;
        x.c = 5;
        s = x;
        if (s.a != 4 || s.c != 5) return 2;
        x = S(2, 3);
        if (x.a != 2 || x.c != 3) return 3;
        x = s;
        if (s.a != 4 || s.c != 5) return 4;
    }
}

// ----
// f() -> 0