connecting overloaded signals to overloaded slots fails

user4592357

i have two signals:

void someSignal();
void someSignal(SomeType type);

and two slots in another class:

void onSomeSignal();
void onSomeSignal(ThatClass::SomeType type);

but when i connect them like this:

connect(widget, qOverload<>(&ThatClass::someSignal,
   this, qOverload<>(&ThisClass::onSomeSignal));
connect(widget, qOverload<ThatClass::Type>(&ThatClass::someSignal),
   this, qOverload<ThatClass::Type>(&ThisClass::onSomeSignal));

i get this error:

error: no match for call to (const QOverload<>) (<unresolved overloaded function type>, ThisClass *, void (ThisClass::*)())
    this, qOverload<>(&ThisClass::onSomeSignal));
                                              ^

also found this somewhere in error:

types R (T::)() const and void (ThatClass::)(ThatClass::Type) have incompatible cv-qualifiers

any idea?

i've also tried to use the old connect style. in that case the first connection (without args) succeeded, the second one (with args) failed.

Christian Ehrlicher

I don't see a major mistake above. Please provide a compilable example.
It does not work with the old style since your signal does not fully qualify the type and therefore the string comparison fails.

user4592357

i think this will do. what i have is similar, but this one compiles fine.
EDIT: found out the problem, in the first connect in what i have i hadn't put a parentheses after signal name...

// header.h
class Widget : public QWidget
{
	Q_OBJECT
public:
	enum Type { ERR };
	Widget()
	{
		emit someSignal();
		emit someSignal(Type::ERR);
	}

signals:
	void someSignal();
	void someSignal(Type type);
};

class Container : public QWidget
{
	Q_OBJECT
public:
	Container(QWidget *parent = nullptr)
	{
		auto widget = new Widget;
		connect(widget, qOverload<>(&Widget::someSignal),
			this, qOverload<>(&Container::onSomeSignal));
		connect(widget, qOverload<Widget::Type>(&Widget::someSignal),
			this, qOverload<Widget::Type>(&Container::onSomeSignal));
	}

public slots:
	void onSomeSignal() {}
	void onSomeSignal(Widget::Type /* type */) {}
};

// main.cpp
#include <QApplication>
#include "header.h"
int main(int argc, char **argv)
{
	QApplication app(argc, argv);

	Container c;
	c.show();

	return QApplication::exec();
}

dheerendra

Did you miss adding closing bracket for the first connect statement ?

user4592357

@dheerendra
yes, i just noticed while copy-pasting the code to a small example.

dheerendra

Missing bracket was the issue.