小编occ*_*zor的帖子

基本上,我有一个

struct foo {
        /* variable denoting active member of union */
        enum whichmember w;
        union {
                struct some_struct my_struct;
                struct some_struct2 my_struct2;
                struct some_struct3 my_struct3;
                /* let's say that my_struct is the largest member */
        };
};

main()
{
        /*...*/
        /* earlier in main, we get some struct foo d with an */
        /* unknown union assignment; d.w is correct, however */
        struct foo f;
        f.my_struct = d.my_struct; /* mystruct isn't necessarily the */
                                /* active member, but is …