qt6 migration issue

[Actarus]

Hi, I'm trying to migrate a project from Q5 to Q6 but trying to build it I get around 1500 errors all related to invalid conversions of all types:

Here an example of the error message:

D:\Development\TestProject\Test\Sampling\Sampling.cpp:11091: error: invalid conversion from 'const char*' to 'char' [-fpermissive]
In file included from D:/Qt/6.5.0/mingw_64/include/QtCore/qstring.h:14,
from D:/Qt/6.5.0/mingw_64/include/QtCore/qobject.h:11,
from D:/Qt/6.5.0/mingw_64/include/QtWidgets/qwidget.h:9,
from D:/Qt/6.5.0/mingw_64/include/QtWidgets/qmainwindow.h:8,
from D:/Qt/6.5.0/mingw_64/include/QtWidgets/QMainWindow:1,
from ..\Test\Sampling\Sampling.h:4,
from ..\Test\Sampling\Sampling.cpp:1:
D:/Qt/6.5.0/mingw_64/include/QtCore/qchar.h:90:45: note: candidate: 'constexpr QChar::QChar(char)' (near match)
90 | QT_ASCII_CAST_WARN constexpr Q_IMPLICIT QChar(char c) noexcept : ucs(uchar(c)) { }
| ^~~~~
D:/Qt/6.5.0/mingw_64/include/QtCore/qchar.h:90:45: note: conversion of argument 1 would be ill-formed:
..\Test\Sampling\Sampling.cpp:11091:42: error: invalid conversion from 'const char*' to 'char' [-fpermissive]

Beeing so many errors all of the same type I assume there is something I made wrong or missing in the environment configuration or installation.

I have the same error also for const char to wchar_t, for const char to short int and many other.

I'm new to sw development so any help is really welcome.

Thanks.

[Christian Ehrlicher]

Please provide a minimal, compileable example of your problem - from the error message I don't see how this should have compiled with Qt5 either - you can not convert a char to a char*.

[Actarus]

@Christian-Ehrlicher Thanks Christian, yes, in QT5 it compiles and runs flowlessly.
Here a piece of code where the error stays in: if(nome.at(c) == " "). error: conversion from 'const char [2]' to 'QChar' is ambiguous

bool ColorRange::on_buttonSalva_pressed()
{
    if(controlloValore())
    {
        if(!ui->checkBoxAutomatico->isChecked())
            cambioDecimali();

        QFile file(folder + /*ui->comboBoxCanali->currentText()*/channelName +".xml");
        if(file.open(QIODevice::WriteOnly))
        {
                       QString nome = channelName;//ui->comboBoxCanali->currentText();
            if(nome.contains(" "))
            {
                for(int c = 0; c < nome.size(); c++)
                    if(nome.at(c) == " ")
                        nome.remove(c, 1);
            }

            QDomDocument xmlDoc(nome);
            QDomElement root = xmlDoc.createElement("root");
            xmlDoc.appendChild(root);

            QDomNode tagAuto = xmlDoc.createElement("Auto");
            root.appendChild(tagAuto);

            QDomText txtAuto;
            if(ui->checkBoxAutomatico->isChecked())
                txtAuto = xmlDoc.createTextNode("1");
            else
                txtAuto = xmlDoc.createTextNode("0");
            tagAuto.appendChild(txtAuto);

            QDomNode tagDecimali = xmlDoc.createElement("Decimali");
            root.appendChild(tagDecimali);

            QDomText txtDecimali = xmlDoc.createTextNode(ui->comboBoxDecimali->currentText());
            tagDecimali.appendChild(txtDecimali);

            for(int i = 0; i <= N_ROWS; i++)
            {
                                if(!ui->table->item(i, 1)->data(Qt::DisplayRole).toString().isEmpty() && ui->table->item(i,0) != nullptr && ui->table->item(i, 2)->checkState() == Qt::CheckState::Checked)
                {
                    QDomNode row = xmlDoc.createElement("Row_" + QString::number(i));
                    root.appendChild(row);

                    QDomElement tagRed = xmlDoc.createElement("R");
                    row.appendChild(tagRed);
                    QDomText txtRed = xmlDoc.createTextNode(QString::number(ui->table->item(i,0)->backgroundColor().red()));
                    tagRed.appendChild(txtRed);

                    QDomElement tagGreen = xmlDoc.createElement("G");
                    row.appendChild(tagGreen);
                    QDomText txtGreen = xmlDoc.createTextNode(QString::number(ui->table->item(i,0)->backgroundColor().green()));
                    tagGreen.appendChild(txtGreen);

                    QDomElement tagBlue = xmlDoc.createElement("B");
                    row.appendChild(tagBlue);
                    QDomText txtBlue = xmlDoc.createTextNode(QString::number(ui->table->item(i,0)->backgroundColor().blue()));
                    tagBlue.appendChild(txtBlue);

                    QDomElement tagValue = xmlDoc.createElement("Valore");
                    row.appendChild(tagValue);
                    QDomText txtValue = xmlDoc.createTextNode(ui->table->item(i, 1)->text());
                    tagValue.appendChild(txtValue);
                }
            }
            file.resize(0);
            QTextStream write(&file);
            xmlDoc.save(write, 3);
        }
        file.close();

        saved = true;
    }
    else
    {
        qDebug()<<"errore nei valori inseriti "<<ui->comboBoxCanali->currentText();
        saved = false;
    }
    return saved;
}
``

[Christian Ehrlicher]

Even in Qt5 this is ... strange - looks like a deprecated conversion jumps in. QString:.at() returns a char, not a char*/string/whatever - imho this would never evaluate to the stuff you expect.
You have to compare it with a char

if(nome.at(c) == ' ')

[JonB]

@Actarus
Absolutely as @Christian-Ehrlicher says, don't know what this did in Qt5.

The sad thing is that whole loop can just be replaced (presumably a lot more efficiently) with:

nome.remove(' ');

:)

[Actarus]

@JonB You both are right but all this is absolutely weird. I recompiled it now on another machine with the original QT5 and no error at all, everything runs perfectly and looking at the code it's exaclty the same.

Also, in QT6, if I compile in release mode it shows me only like 10 of these errors, if I switch to Debug and compile they jump to around 1500 errors of this type.

[Actarus]

@Actarus For example this is another error I get in QT6:

while in debug mode in QT5 I get the following, even if it compiles with no error in release mode in QT5:

[Christian Ehrlicher]

Yes, because it has changed - see the documentation to QWidget::enterEvent() and fix your code accordingly.

[Actarus]

@Christian-Ehrlicher Thanks, that has been fixed. Now trying to figure out the first issue and guessing why in QT5 it can work.

[Christian Ehrlicher]

@Actarus said in qt6 migration issue:

guessing why in QT5 it can work.

Implictly converting a char* into a QString is wrong so... don't think about it but fix it.

[Actarus]

@Christian-Ehrlicher I'll do. Now I fixed another issue about the following where I changed X, that was deprecated, to position

//if ((0 == m_ChartViewer) || (!isOnPlotArea(event->x(), event->y())))
    if ((0 == m_ChartViewer) || (!isOnPlotArea(event->position().x(), event->position().y())))
        event->ignore();

but now it shows me the following error on that line:

[JonB]

@Actarus
The implication is that isOnPlotArea() only accepts a QPointF. (Documentation seemingly at https://www.advsofteng.com/doc/cdcppdoc/ViewPortControlBase.isOnPlotArea.htm notwithstanding.)
Put your cursor in that method name and press F2. Does it take you to the header file? What overloads of isOnPlotArea() are there?
Also does this error occur when you compile or only visible within Creator?

[Actarus]

@JonB Thanks Jon, fixed, pressing F2 it jumped to the header where I had:
bool isOnPlotArea(QPointF x, QPointF y)

changed to: bool isOnPlotArea(double x, double y) and now it's fine.

[JonB]

@Actarus said in qt6 migration issue:

changed to: bool isOnPlotArea(double x, double y) and now it's fine.

Ummm, gulp :) Your header file or Qt's??

[Actarus]

@JonB Mine, it had been edited wrongly to fix a previous error message.

I have fixed tons of parts now but I'm still struggling with around 15 errors like this:

error: qualified-id in declaration before '(' token
error: qualified-id in declaration before '(' token
| void ChartsAxis::sectionHasBeenClicked(int logicalIndex)
|

Here the example code:

void ChartsAxis::sectionHasBeenClicked(int logicalIndex)
{
    if((isComp)&&(logicalIndex > 0))
    {
        bool found = false;
        int index = 0;
        for(int is = 0; is < pStructComp->size(); is++)
        {
            for(int il = 0; il < pStructComp->at(is)->giri.size(); il++)
            {
                index++;
                if(index == logicalIndex)
                {
                    QFont f;
                    f.setBold(true);
                    if(this->width()-frame->width() >= 600)
                    {
                        labelOffset->setGeometry((this->width()-frame->width())/2 - 300, 0, 600, 20);
                        f.setPixelSize(15);
                    }
                    else if(this->width()-frame->width() >= 380)
                    {
                        labelOffset->setGeometry((this->width()-frame->width())/2 - 190, 0, 380, 20);
                        f.setPixelSize(11);
                    }
                    else
                    {
                        labelOffset->setGeometry(0, 0, (this->width()-frame->width()), 20);
                        f.setPixelSize(11);
                    }
                    labelOffset->setFont(f);
                    labelOffset->show();
                    found = true;
                    emit setOffsetIndex(is, il);
                    break;
                }
            }
            if(found)
                break;
        }
    }
}

[JonB]

@Actarus
The error message is complaining on the method definition line, so showing its body is not relevant as it does not get that far. For "Function definition not allowed here" you may have to look back a few lines for context, e.g. (only an example) if previous function not properly terminated with a } it might generate this message. Make sure it marries with the included header declaration too.

[Actarus]

@JonB Thanks Jon, all sorted with } a few lines above.

Can you help in correcting the sintax for QT6 for the following line of QTableWidgetItem:

colorPicker = new QColorDialog(ui->table->item(r, 0)->backgroundColor(), nullptr

I corrected replacing backgroundColor with background, but I can't get the correct sintax.

I still have only 2 last errors to fix, the first is the one above and the last one is this below, for which I can't find anything online:

Thanks

[jsulm]

@Actarus said in qt6 migration issue:

and the last one is this below

This is not the error message.
Please post the real error which is above that line...
It is also better to post error as text not images.

[Actarus]

@jsulm This is what above that line in Compile Output window:

g++ -c -fno-keep-inline-dllexport -g -Wall -Wextra -Wextra -fexceptions -mthreads -DUNICODE -D_UNICODE -DWIN32 -DMINGW_HAS_SECURE_API=1 -DQT_DEPRECATED_WARNINGS -DCHARTDIR_HIDE_OBSOLETE -D_CRT_SECURE_NO_WARNINGS -DQT_PRINTSUPPORT_LIB -DQT_QUICKWIDGETS_LIB -DQT_WIDGETS_LIB -DQT_QUICK_LIB -DQT_OPENGL_LIB -DQT_GUI_LIB -DQT_CORE5COMPAT_LIB -DQT_QMLMODELS_LIB -DQT_QML_LIB -DQT_QMLINTEGRATION_LIB -DQT_BLUETOOTH_LIB -DQT_NETWORK_LIB -DQT_SQL_LIB -DQT_SERIALPORT_LIB -DQT_POSITIONING_LIB -DQT_XML_LIB -DQT_CORE_LIB -DQT_NEEDS_QMAIN -I../Test -I. -I../Test/Charts -I../Test/Charts/Tables -I../Test/Charts/JSONObjects -I../Test/Archivio -I../Test/Comp -I../Test/Parse -I../Test/Bluetooth -I../Test/MD5 -I../Test/Devs -I../Test/Devs/DevicesFactory -I../Test/Conf -I../Test/Usb -I../Test/Triggers -I../Test/SubClass -I../Test/Server -I../Test/Exporter -I../Test/Wifi -IC:/Projects/QT_Project/Test/ZipPack/include -IC:/Projects/QT_Project/Test/LimeReport/Release/include -I../include -I../../../Qt/6.5.0/mingw_64/include -I../../../Qt/6.5.0/mingw_64/include/QtPrintSupport -I../../../Qt/6.5.0/mingw_64/include/QtQuickWidgets -I../../../Qt/6.5.0/mingw_64/include/QtWidgets -I../../../Qt/6.5.0/mingw_64/include/QtQuick -I../../../Qt/6.5.0/mingw_64/include/QtOpenGL -I../../../Qt/6.5.0/mingw_64/include/QtGui -I../../../Qt/6.5.0/mingw_64/include/QtCore5Compat -I../../../Qt/6.5.0/mingw_64/include/QtQmlModels -I../../../Qt/6.5.0/mingw_64/include/QtQml -I../../../Qt/6.5.0/mingw_64/include/QtQmlIntegration -I../../../Qt/6.5.0/mingw_64/include/QtBluetooth -I../../../Qt/6.5.0/mingw_64/include/QtNetwork -I../../../Qt/6.5.0/mingw_64/include/QtSql -I../../../Qt/6.5.0/mingw_64/include/QtSerialPort -I../../../Qt/6.5.0/mingw_64/include/QtPositioning -I../../../Qt/6.5.0/mingw_64/include/QtXml -I../../../Qt/6.5.0/mingw_64/include/QtCore -Idebug -I. -I/include -I../../../Qt/6.5.0/mingw_64/mkspecs/win32-g++ -o debug\chartmappa.o ..\Test\Charts\chartmappa.cpp
mingw32-make[1]: *** [Makefile.Debug:32897: debug/colorrange.o] Error 1

[JonB]

@Actarus said in qt6 migration issue:

debug/colorrange.o] Error 1

Strange, because that colorrage.o file is not even mentioned on the previous line, which may have been completed successfully. make may be moving on to build the next file alphabetically. Errno 1 would be "EPERM". Does debug/colorrange.o already exist? Are you able to delete it?