QFormLayout does not calculate width of rows without label properly

#include <QtWidgets>

int main(int argc, char** argv)
{
  QApplication app(argc, argv);
  QWidget w;
  QFormLayout* ll = new QFormLayout(&w);
  ll->setWidget(0, QFormLayout::LabelRole, new QLabel("123245689"));
  ll->setWidget(0, QFormLayout::FieldRole, new QSpinBox);
  ll->setWidget(1, QFormLayout::FieldRole, new QCheckBox("some other text"));
  w.show();
  app.exec();
}