The title explains it all, I'll just add an example.

class MyObject : public QObject
{
    Q_OBJECT
    Q_CLASSINFO("DefaultProperty", "data")
...
};

MOC will generate this C++ code for Q_CLASSINFO:

...

static const char qt_meta_stringdata_MyObject[] = {
    "MyObject\0data\0DefaultProperty\0"
};  

const QMetaObject MyObject::staticMetaObject = {
    { &QObject::staticMetaObject, qt_meta_stringdata_MyObject,
      qt_meta_data_MyObject, 0 }
};