If f1 calls f2 that calls f1 why can't the compiler inline f2 into the body of f1? It's not so complicated if the compiler has annotations or other hints to guide it.
I once wrote an interpreter in continuation-passing style, meaning every final line of a function called the next function in the interpreter, passing a continuation and error continuation on.
Such a program never returns until it finishes interpreting, and can make an unlimited number of such calls.
