I tried to copy some source from here for compiling and ran into the old "stray '\240' in program" error. I tried MicroGoldED, MutliEdit, NotePad, Ed and Memacs. None filtered it out nor did I see any option to filter it down to basic ASCII.
I also tried my own program that cuts off the high bit and can replace non-ASCII chars but found it just messes up all the lines and caused an error in the code.
So what Amiga/OS4 programs are there or editors that can save a program in generic ASCII?