QMAKE_CXX.COMPILER_MACROS is not defined

[Panda281]

Hi together,

I just wanted to work with a "Getting Started with Qt5"-book and a "Hello-World"-project but now I have some difficulties when
using qmake in a termial / console i.e. not using Qt-Creator. So here is my source ( not really spectacular ):

#include <QApplication>
#include <QLabel>
 
int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QLabel label("Hallo Werner!");
    label.show();
    return app.exec();
}

#include <QApplication>
#include <QLabel>

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    QLabel label("Hallo Werner!");
    label.show();
    return app.exec();
}

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"qmake" is not found but "qmake6" is found and returns help-information.
"qmake6 -project" returns "Variable QMAKE_CXX.COMPILER_MACROS is not defined." but a
project-file is created.
When I type "qmake6" again, then a Makefile is also created.

But when I finally type "make" then I get "

hello.cpp:1:10: fatal error: QApplication: Datei oder Verzeichnis nicht gefunden
1 | #include <QApplication>
| ^~~~~~~~~~~~~~

In Qt-Create under settings->kits I get with "Desktop Qt 6.4.2 GCC 64bit" an orange warning
sign and the warning:
The CMAKE-Configuration has set a C-compiler although the kit has no valid toolchain.

Anyway the QLibraries are not found.

Op-system ist OpenSuse-Linux Leap 15.4,
Installation is non commercial and was done using the Qt-Maintenance Tool.

Any hint what is wrong with my installation? Under Qt4 everything worked fine.

Best regards
Werner