what would lead to crash while getting QwtPlotItem rtti value ?

[lwz]

I have a snap of code like this :

void updateCurves {
QwtPlotItemList list = plot->itemList();
foreach (QwtPlotItem * item, list) {
qDebug() << " updateCurvesPosition1 " << item;
qDebug() << "updateCurvesPosition 1 " << item->rtti();
if (item->rtti() == QwtPlotItem::RttiValues(BaseCurve::Rtti_BaseCurveS tyle) ) {
BaseCurve *curve = static_cast<BaseCurve *>(item);
BaseLegendConfigData::CurveType type = curve->curveConfig()->getCurveType();
......

}
}

replot();

QwtPlotItemList curlist = plot->itemList();
foreach (QwtPlotItem *item, curlist) {
qDebug() << " updateCurvesPosition 2" << item;
qDebug() << "updateCurvesPosition 2 " << item->rtti(); /// crash here .
if (item->rtti() == QwtPlotItem::RttiValues(BaseCurve::Rtti_BaseCurveS tyle)) {
BaseCurve *curve = static_cast<BaseCurve *>(item);
.........
}
}
}
}



The first part and the second part are almost the same, but the red line would cause crash.

---

Added after 16 minutes:

o , i know why , sorry ,my mistake.