main.cpp

#include <QtWidgets>

int main(int argc, char **argv)
{
    QApplication app(argc, argv);

    QToolButton button;
    QAction action(&button);
    action.setShortcut(QKeySequence("X"));
    button.addAction(&action);
    QObject::connect(&action, &QAction::triggered, [=]() {
        qDebug() << "test";
    });

    button.show();
    return app.exec();
}