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  1. Qt
  2. QTBUG-90308

REG: uic creates ambiguous signal/slot connections

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    • 98a89fb711a15fcf9f541f7b4a8ae7492e5a445c (qt/qtbase/dev) e0fecdc7bc7b3dbd6a6f9046d43450b3bdd38a60 (qt/qtbase/6.0)

    Description

      Since Qt 6, uic has started producing invalid connection statements when the signal or slot has overloads.

      To reproduce (how the attached example was produced):
      1. Create a "Qt Widgets" application using the template in Qt Creator
      2. Go to the form editor and add a vertical slider to the form
      3. Enter signal/slot editing mode and create a connection from slider to widget parent
      4. Make sure "inherited from QWidget" is checked, then pick "valueChanged(int)" on the slider and "repaint()" on the widget.
      5. Try to compile.

      With Qt 5.15 it produces the following code:

      QObject::connect(verticalSlider, SIGNAL(valueChanged(int)), Widget, SLOT(repaint()));

      Which works fine.

      But with Qt 6 uic produces the following code: 

      QObject::connect(verticalSlider, &QSlider::valueChanged, Widget, &QWidget::repaint);

      This fails to compile, because QWidget::repaint is ambiguous:

      C:\dev\diverse\bugs\build-uicSignals-Qt_dev-Debug\ui_widget.h(41): error C2665: 'QObject::connect': none of the 3 overloads could convert all the argument types
C:\dev\qt5-dev\base\include\QtCore\../../src/corelib/kernel/qobject.h(441): note: could be 'QMetaObject::Connection QObject::connect(const QObject *,const char *,const char *,Qt::ConnectionType) const'
C:\dev\qt5-dev\base\include\QtCore\../../src/corelib/kernel/qobject.h(198): note: or       'QMetaObject::Connection QObject::connect(const QObject *,const QMetaMethod &,const QObject *,const QMetaMethod &,Qt::ConnectionType)'
C:\dev\qt5-dev\base\include\QtCore\../../src/corelib/kernel/qobject.h(195): note: or       'QMetaObject::Connection QObject::connect(const QObject *,const char *,const QObject *,const char *,Qt::ConnectionType)'
C:\dev\diverse\bugs\build-uicSignals-Qt_dev-Debug\ui_widget.h(41): note: while trying to match the argument list '(QSlider *, void (__cdecl QAbstractSlider::* )(int), QWidget *, overloaded-function)'

      In this case, I think qOverload() is needed to disambiguate the slot.

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          resulted from

          Bug - A problem which impairs or prevents the functions of the product. QTBUG-76375 Qt 6: Connection syntax migration

          • P2: Important - Urgent, should be fixed, but will not stop the release.
          • Reported
          For Gerrit Dashboard: QTBUG-90308
          # Subject Branch Project Status CR V
          330196,9 Hardcode a special case of using qOverload for slots without arguments dev qt/qtbase Status: MERGED +2 0
          330351,2 Hardcode a special case of using qOverload for slots without arguments 6.0 qt/qtbase Status: MERGED +2 0

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            People

              jkobus Jarek Kobus
              esabraha Eskil Abrahamsen Blomfeldt
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              Dates

                Created:
                Updated:
                Resolved:

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