/* hash structure: */
/* This structure must match the beginning of struct xpvmg in sv.h. */
struct xpvhv {
    HV*         xmg_stash;      /* class package */
    union _xmgu xmg_u;
    STRLEN      xhv_keys;       /* total keys, including placeholders */
    STRLEN      xhv_max;        /* subscript of last element of xhv_array */
};