Hi, I'm "this guy". Thanks for pointing out -fpermissive, which was needed during the conversion for the legacy code. Since then I fixed all the warnings, so I can remove the flag (https://github.com/das-labor/neopg/commit/5359aab7885628554c...).

I would love to do code review, but I need a second developer for that!

Thank you for your interest and taking the time to write down your criticism.