emscripten_set_mousedown_callback does not call the callback function

[8Observer8]

emscripten_set_mousedown_callback does not call the callback function. I expect to see the output in the console but I see nothing:

#include <QtWidgets/QApplication>
#include <QtWidgets/QWidget>

#include <emscripten.h>
#include <emscripten/html5.h>

class Widget : public QWidget
{

public:

    Widget()
    {
        emscripten_set_mousedown_callback(EMSCRIPTEN_EVENT_TARGET_WINDOW, nullptr, 0, +[](int eventType,
            const EmscriptenMouseEvent* e, void* userData) -> EM_BOOL
        {
            qDebug() << "Mouse down: " << e->button;
            return EM_FALSE;
        });
    }
};

int main(int argc, char *argv[])
{
    QApplication app(argc, argv);
    Widget w;
    w.show();
    return app.exec();
}

[8Observer8]

Bug report: https://bugreports.qt.io/browse/QTBUG-126582

[8Observer8]

I have tried to make an "Empty qmake Project":

pro

wasm: INCLUDEPATH += "C:\emsdk\upstream\emscripten\cache\sysroot\include"

SOURCES += \
    main.cpp

main.cpp

#include <emscripten.h>
#include <emscripten/html5.h>
#include <iostream>

// https://github.com/emscripten-core/emscripten/issues/19266
int main()
{
    // Mouse Button Down:
    emscripten_set_mousedown_callback(
        EMSCRIPTEN_EVENT_TARGET_WINDOW, nullptr, 0, +[](int eventType,
        const EmscriptenMouseEvent *e, void *userData) -> EM_BOOL
        {
            std::cout << "Mouse down: " << e->button << "\n";
            return EM_FALSE;
        });
}

It doesn't print the output to the console when I click.

But it works when I compile from the console:

emcc -g main.cpp -o public/index.html

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The Emscripten issue: emscripten_set_mousedown_callback does not call the callback function from Qt Creator