c++ - QObject::connect crash at signalOffset(senderMetaObject) due to QMetaObject::superdata contains null data -

my connection code following:

qobject::connect(_scene, &vscene::activeobjectchanged, _scene->manipulatornode(), &vmanipulatornode::onactiveobjectchanged); 

vscene subclass of vnode, subclass of qobject. both of them contain q_object macro.

vscene signal sender:

class vscene : public vnode {     q_object     public slots:     void        markactiveobject(vobject *obj);     void        unmarkactiveobject(vobject *obj); signals:     void        activeobjectchanged(vobject *obj); } 

vnode:

class vnode : public qobject {     q_object } 

vmanipulator:

class vmanipulatornode : public vnode { public:     void onactiveobjectchanged(vobject *obj); } 

the program crashes while calling qobject::connect, @ function

    signal_index += qmetaobjectprivate::signaloffset(sendermetaobject); 

whiling debugging, found out superdatapointer of qmetaobject of sender vscene contains null data.

i see qmetaobject of vscene point qmetaobject of vnode, , then, qmetaobject of vnode point qmetaobject of qobject. here, @ crash position, qmetaobject of vscene contains null data

all moc files, including moc_vscene , moc_vnode, generated qt.

moc_vscene.cpp:

const qmetaobject vk::vscene::staticmetaobject = { { &vnode::staticmetaobject, qt_meta_stringdata_vk__vscene.data,   qt_meta_data_vk__vscene,  qt_static_metacall, q_nullptr, q_nullptr} }; 

moc_vnode.cpp:

struct qt_meta_stringdata_vk__vnode_t { qbytearraydata data[1]; char stringdata0[10]; }; #define qt_moc_literal(idx, ofs, len) \     q_static_byte_array_data_header_initializer_with_offset(len, \     qptrdiff(offsetof(qt_meta_stringdata_vk__vnode_t, stringdata0) + ofs \     - idx * sizeof(qbytearraydata)) \ ) static const qt_meta_stringdata_vk__vnode_t qt_meta_stringdata_vk__vnode = {     {         qt_moc_literal(0, 0, 9) // "vk::vnode"     },     "vk::vnode" }; #undef qt_moc_literal  static const uint qt_meta_data_vk__vnode[] = {   // content:    7,       // revision    0,       // classname    0,    0, // classinfo    0,    0, // methods    0,    0, // properties    0,    0, // enums/sets    0,    0, // constructors    0,       // flags    0,       // signalcount     0        // eod };  void vk::vnode::qt_static_metacall(qobject *_o, qmetaobject::call _c, int     _id, void **_a) {     q_unused(_o);     q_unused(_id);     q_unused(_c);     q_unused(_a); }  const qmetaobject vk::vnode::staticmetaobject = {     { &qobject::staticmetaobject, qt_meta_stringdata_vk__vnode.data,   qt_meta_data_vk__vnode,  qt_static_metacall, q_nullptr, q_nullptr} }; 

note: while debugging in visual studio, it's shown vnode::staticmetaobjectcontains null data, it's strange of static member including qt_meta_stringdata_vk__vnode , qt_meta_data_vk__vnode right (non-null). here evidence

the code emitting signal:

void vscene::markactiveobject(vobject *obj) {     if (obj){         obj->markactive();         emit activeobjectchanged(obj);     } } 

the first thing notice should change:

public:     void onactiveobjectchanged(vobject *obj); 

to:

public slots:     void onactiveobjectchanged(vobject *obj); 

not sure info given if solve it, not right.