Qt6 signals and slots connect issue

[JonB]

@Agostinho
You have shown the error messages but not the code causing them.

In file included from ../../untitled5/mainwindow.cpp:2:

./ui_mainwindow.h:56:18: error: no matching member function for call to 'connect'

Show us the first couple of lines from mainwindow.cpp, and more importantly let's see the ui_mainwindow.h generated.

[jsulm]

@JonB said in Qt6 signals and slots connect issue:

You have shown the error messages but not the code causing them.

He connects in the designer, not in code

[Agostinho]

@JonB I did not modify the default mainwindow.cpp and mainwindow.h created by qt designer.

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QAbstractSlider>
#include <QLCDNumber>
MainWindow::MainWindow(QWidget *parent)
  : QMainWindow(parent)
  , ui(new Ui::MainWindow)
{
  ui->setupUi(this);
}

MainWindow::~MainWindow()
{
  delete ui;
}

In fact, the error is produced on ui_mainwindow.h in the following line:

  QObject::connect(horizontalSlider, &QSlider::valueChanged, lcdNumber, &QLCDNumber::display);

It is just where the new signal/slot connect syntax changes from the old syntax!

[jsulm]

@Agostinho The problem is that there are several overloaded versions of the display() slot

[jsulm]

@Agostinho You can connect manually like this:

connect(ui->horizontalSlider, &QSlider::valueChanged, ui->lcdNumber, QOverload<int>::of(&QLCDNumber::display));

See https://doc.qt.io/qt-5/qtglobal.html#qOverload

[Pl45m4]

@jsulm said in Qt6 signals and slots connect issue:

The problem is that there are several overloaded versions of the display() slot

Thought the same, but can't you select one of them by clicking, when connecting widgets in QtCreator's Design mode?!
Haven't used it for a long time. And I problably never will. For a reason :)

[Agostinho]

@jsulm I works, but this exact line should be generated automatically by the uic. Should I blame uic? I hope so! :)

[jsulm]

@Pl45m4 said in Qt6 signals and slots connect issue:

Haven't used it for a long time.

I also don't use Designer to connect signals/slots, so don't know

[jsulm]

@Pl45m4 Qt5 uses old connect syntax, so it looks like this:

QObject::connect(horizontalSlider, SIGNAL(valueChanged(int)), lcdNumber, SLOT(display(int)));

Qt6 seems to use new connect syntax, but I did not check how the generated connect looks like (don't have Qt6 at hand).

[Agostinho]

@jsulm Anyway, thanks for help. Best regards.