Typedef report joystick USB

typedef union {
    char bytes[4];
    struct {
        char x_value;
        char y_value;
        unsigned pov_hat :4;
        unsigned button_1 :1;
        unsigned button_2 :1;
        unsigned button_3 :1;
        unsigned button_4 :1;
        unsigned button_5 :1;
        unsigned button_6 :1;
        unsigned button_7 :1;
        unsigned button_8 :1;
        unsigned button_9 :1;
        unsigned button_10:1;
    };
} T_USB_Report;