SetVisible doesn't work on action set as a separator in a QToolBar

I create a QAction as a separator (use setSeparator on the QAction).

I had the QAction in a QToolBar.

I don't want to show this separator (because icons between two separators are hidden, or because separators are at the beginning of the toolbar or at the end).

I call action->setVisible(false)

The separator is always visible in the QToolBar.

Thanks