As far as I know, the following lines should be equivalent :

QObject::connect(ui->button, &QPushButton::clicked, this, []() {});
QObject::connect(ui->button, &QAbstractButton::clicked, this, []() {});

Most examples and Qt sources tends to favor the first using the actual widget class. Does it make any difference ? And if there are, what are the benefits/drawbacks of both ?

The second makes code less susceptible to UI changes (replacing QPushButton with QRadioButton for example), and in any case, if the class/method doesn't match, it would result in a build error. I don't know if this is even possible, but the derived class could hide the signal from the base class causing issues, no ?

Thank you in advance !