This is defined in the official core. It is not used anywhere in the official core.
It's a very complicated definition:
#define analogInPinToBit(P) (P)
Anyone know what exactly it does? I'm trying to figure out
a) whether it is in use in the wild or if it's just litter in the files that was left there because nobody knew what it was for but I'd better leave it for compatibility
b) whether any of my cores would need a more complicated definition of this macro if so.
If nothing actually calls it, I should gun it. The only time I've seen it used, it was used like digitalPinToAnalogInput() in an older core - but that ain't what the current form of it does!..... (but there it's internal to the core)
unless I can find evidence of it being used anywhere, I'm sorely tempted to comment it out and see if anyone complains