Thank you, as always, very much for getting back to us!
For the sake of transparency: ListenerList crashes on AudioProcessor destruction - #41 by Rincewind
this is the comment we are talking about and it was also concerning a „missing“ garantee of ListenerList to be thread safe when only calling from multiple threads. And I believe this is the main point outlined by the OP.
I also think your conclusion is correct, that making call const would solve this problem, even though it never was const in the first place.
I’m making the case, that a lot of code used this function as if it were const (with all benefits of it) after looking at the implementation detail and noticing it would not be a problem for thread safety or real time threads.
EDIT: of course @anthony-nicholls your are correct from a programmers point of view. I’m just making the case for the legacy code base and beginners or people, that looked for thread safety and deemed it to be. Before the changes to ListenerList the past months, it was a very simple class IMO. That’s not the case anymore and that suprised at least me. I have been using the class a lot not needing all the safety rails.