Attempting to send a synthetic XInput2 event through XSendEvent() fails with a BadValue error:

    Display display = /* ... */;
    Window window = /* ... */;
    XIDeviceEvent event = {
        .type = GenericEvent,
        .display = display,
        .extension = xinput2_opcode,
        .evtype = XI_TouchBegin,
        /* ... */
    };
    XSendEvent(display, window, False, 0, (XEvent *)&event);  // => BadValue

The same happens if I try to wrap the XIDeviceEvent in an XGenericEventCookie:

    XGenericEventCookie cookie;
    memcpy(&cookie, &event, sizeof(cookie));
    cookie.cookie = 0;
    cookie.data = &event;
    XSendEvent(display, window, False, 0, (XEvent *)&cookie);  // => BadValue

This issue appears to have been raised previously in bug 30357 (through 30361), but despite that being marked FIXED, XSendEvent() still fails with xorg-server 1.17.1, libX11 1.6.2, and libXi 1.7.4, and I don't see that any of the patches from those bugs have been applied.  FWIW, after applying those patches (with minor tweaks) I can successfully send wrapped XIDeviceEvent events through XSendEvent().