QObject::connect: signal not found in promoted widget with Lambda syntax - c++

Question

I have an overloaded QTreeWidget class, with my SIGNALS: I have promoted it in my UI and when I listen promoted QTreeWidget object with a lambda syntax I have an error.
QObject::connect: signal not found in CustomTreeWidget.
MY CustomTreeWidget looks like:
.h
class CustomTreeWidget : public QTreeWidget
{
Q_OBJECT
public:
explicit CustomTreeWidget(QWidget *parent = 0);
~CustomTreeWidget() {
}
signals:
void currentNodeChanged(QSet<int> uids);
void deleteRequest(QVector<int> uids);
}
.cpp
CustomTreeWidget::CustomTreeWidget(QWidget *parent) : QTreeWidget(parent)
{
setAnimated(true);
connect(this, &CustomTreeWidget::customContextMenuRequested, this, [=](const QPoint &pos) {
this->m_bCustomMenuOpen = true;
const auto &&item = this->itemAt(pos);
QMenu myMenu;
bool ok = !(item) ? false : true;
if (ok) {
//თუ topLevelItem -ია მხოლოდ დამატების action -ი უნდა იყოს ჩართული.
if (item == this->topLevelItem(0) || item == this->topLevelItem(0)->child(0)) {
ok = false;
}
}
QAction *Removecnt = myMenu.addAction(tr("&წაშლა"), this, SLOT(DeleteNode()));
Removecnt->setIcon(QIcon(":/global_res/delete.png"));
Removecnt->setEnabled(ok);
myMenu.exec(this->mapToGlobal(pos));
});
}
void CustomTreeWidget::BFS(QTreeWidgetItem *item, QSet<int> &out)
{
std::queue<QTreeWidgetItem *> Q;
Q.push(item);
while (!Q.empty()) {
QTreeWidgetItem *now = Q.front(); Q.pop();
out.insert(this->m_mapUids[now]);
for (int i = 0; i < now->childCount(); i++) {
Q.push(now->child(i));
}
}
}
QSet<int> CustomTreeWidget::GetCurrentNodeUids()
{
QSet<int> uids;
if (!this->currentItem())
return uids;
this->BFS(this->currentItem(), uids);
return uids;
}
void CustomTreeWidget::DeleteNode()
{
QSet<int> nodes = this->GetCurrentNodeUids();
QVector<int> uids;
for (auto it : nodes) {
uids.push_back(it);
}
emit deleteRequest(uids);
}
My lambda looks like:
connect(ui->productTree, &CustomTreeWidget::deleteRequest, this, [=](QVector<int> uids) {
//logic
});
But this signal works with old syntax.
connect(ui->productTree, SIGNAL(deleteRequest(QVector<int>)), this, SLOT(checkSlot(QVector<int>)));
And this slot is.
void ProductForm::checkSlot(QVector<int> uids)
{
qDebug() << uids.size();
}
So what is problem lambda syntax?

Answer 1

This smells like the violation of the one definition rule (ODR) - perhaps due to a stale build folder. The problem is that the address of deleteRequest passed to the connect method is not the same as the address of the method visible from moc_CustomTreeWidget.cpp. Remove the build folder and try again. If it still doesn't work, start reducing your problem:
Create a minimization branch in the repository (if you're not using version control, you won't go anywhere with minimization).
Copy-paste the contents of the ui_CustomTreeWidget.h file into the CustomTreeWidget.cpp file, remove the #include line.
Inspect the pasted contents for instantiation of the productTree object with the correct type.
If that's correct, then remove everything else from the code, step-by-step, rebuilding and committing to the repository at each step that still reproduces. You should end up with a test case that is 20-30 lines long at most. And it'll be either obvious what's wrong, or you can modify the question with the test case.