This entire thread has gone seriously off the rails.
We are not going to invent a whole new language mechanism for expressing parameter function optionality. It should be quite straightforward to extend escape analysis to optional parameter functions and allow them to be explicitly marked as @escaping or @nonEscaping (or however we want to spell that). We can also investigate changing the default language rule for optional parameter functions so that it's consistent for different optionalities, but that's a separable question.