It seems this problem is related to Arduino IDE cache. And some people are looking for the way to clear it in order to rid of the "old stuff". And there is no convenient way to do that as for now
I use a build_opt.h file in the sketch to set options in the processor core and or/library.
The problem is that swapping between sketches with different build options fails to work correctly because of caching.
The clumsy way around this is to swap to a different processor and compile to force a cache flush. Closing the IDE and opening again no longer clears the cache.
I understand that the Arduino IDE is for "beginners" but with new features like debugging etc it seems to be moving away from…
The pre-compiling and caching is really convenient most of the time, but what can I do to force the IDE to compile everything again, including all libs, and core, and what have you?