Почему не дает shared_ptr от this? - C++ - Ответ 7205901

OwnProject::OwnProject(OwnManager * Manager, const QString & Filename)
    : manager(/*Manager->get_shared_ptr()*/ shared_ptr<OwnManager>(Manager)),
      filename(Filename)
{
    qDebug() << "[dbg]\t\tCalling c-tor for OwnProject (2nd)";
    nameOfProject =
            QFileInfo(filename).completeBaseName();
    file =
            make_shared<OwnProjectFile> (this, filename);
    rootNode =
            make_shared<OwnProjectNode> (this, file);
 
    Core::DocumentManager::addDocument(file.get(), false); //or true? or even - are we need this?
 
}

std::shared_ptr<OwnProject> OwnProject::get_shared_ptr()
{
    qDebug() << "[dbg]\t\tGetting shared_ptr from this of OwnProject instance";
    return shared_from_this();
}
/*mem

return /*nullptr*/ new OwnProject(get_shared_ptr(), Filename);

OwnProject::OwnProject(shared_ptr<Internal::OwnManager> Manager, const QString & Filename)
    : manager(Manager),
      filename(Filename)
{
    qDebug() << "[dbg]\t\tCalling c-tor for OwnProject (1st)";
    nameOfProject =
            QFileInfo(filename).completeBaseName();
    file =
            make_shared<OwnProjectFile> (this, filename);
    rootNode =
            make_shared<OwnProjectNode> (this, file);
 
    Core::DocumentManager::addDocument(file.get(), false); //or true? or even - are we need this?
    
}