hen@bu-cs.UUCP (Bill Henneman) (09/20/85)
Judging from recent traffic, there seems to be an overwhelmingly popular opinion that detection of recursion has to be done in the dumbest possible fashion. Yes, it is true that you can write a routine which would make both errors of inclusion and errors of exclusion when trying to build a call graph: it is equally true that you can build an editor with no command to save the buffer, or a mail routine that will not send mail to the local site. But you don't have to. Compiled languages place restrictions on what the programmer can say. LISP may allow (go (read)) but this is disallowed in any compiled language I know: the set of possible labels must be explicitly available. Same with calls. The point of the above observation is that, in every language I'm familiar with, you can write a symbolic execution module to help build your call tree without fear of running into a halting problem situation. It takes a lot more investment in coding (you have to write a bunch of simplification routines for assertions, etc.), but you can write a recursion detector which is not quite as stupid as the netters assume. Bill Henneman Boston University