error C2440: 'static_cast': cannot convert from 'const QObject *' to 'T'

[Pradson]

Hi,

I am facing the below mentioned compilation error when I am porting my Qt5 application to Qt6. Kindly suggest the solution-

------------Compilation Error------------
C:\Qt\Qt6.4.0\6.4.0\msvc2019_64\include\QtCore\qobject.h(455): error C2440: 'static_cast': cannot convert from 'const QObject *' to 'T'
with
[
T=QDesignerCustomWidgetInterface *
]
C:\Qt\Qt6.4.0\6.4.0\msvc2019_64\include\QtCore\qobject.h(455): note: Conversion loses qualifiers
sharedFiles\pluginwidgetmanager.cpp(545): note: see reference to function template instantiation 'T qobject_cast<QDesignerCustomWidgetInterface>(const QObject *)' being compiled
with
[
T=QDesignerCustomWidgetInterface *
]

Thanks,

[jsulm]

@Pradson You're trying to cast a const object to a non-const object. Either cast from const to const or change "const QObject *" to "QObject *" depending on your needs. Or cast to "const QDesignerCustomWidgetInterface *".

[Pradson]

@jsulm

Thanks a lot.

Now, I am getting the below mentioned another compilation error when porting from Qt5 to Qt6-

---------- Compilation Error -----------
widgets.table(113): error C2027: use of undefined type 'QOpenGLWidget'

Kindly suggest the solution.

Thanks,

[jsulm]

@Pradson said in error C2440: 'static_cast': cannot convert from 'const QObject *' to 'T':

Kindly suggest the solution

Documentation already does: https://doc.qt.io/qt-6/qopenglwidget.html
Do you have this line in your pro file:

QT += openglwidgets

Or, in case you're using CMake:

find_package(Qt6 REQUIRED COMPONENTS OpenGLWidgets)
target_link_libraries(mytarget PRIVATE Qt6::OpenGLWidgets)

in CMakeLists.txt

[Pradson]

@jsulm

Hi,

I have already added the the above suggestion (QT += openglwidgets) in my .pro file. Still, I am getting the same error as mentioned below-

------------ Compilation Error-------------
..\lib\myuilib\widgets.table(113): error C2027: use of undefined type 'QOpenGLWidget'
C:\Qt\Qt6.4.0\6.4.0\msvc2019_64\include\QtGui/qpixmap.h(137): note: see declaration of 'QOpenGLWidget'

Thanks,

[jsulm]

@Pradson Did you also include the header file (#include <QOpenGLWidget>)?

[Pradson]

@jsulm

Thanks a lot for your kind support.

Now, the compilation errors have been gone.

Thanks,