@mmel I also find it odd that you were the first to suggest an enum.
That's a misunderstanding. It seems I was too brief and probably inaccurate. I apologize for that.
I always meant to say that INTR_TYPE should not be a #define with bitfield-like values, but with enum-like values.
Given my aversion to having enum in interfaces, it didn't occur to me at all that someone might take that as a recommendation to use enum. My bad, I'll try not to repeat it next time.