if you're looking for callers, use the built-in caller() function.

You are correct, in that there will not be an error message until the non-existant function is (attempted to be) called. This is because when the program is invoked, perl has no way to know whether or not the function will exist when it is called. Functions can be created at run time, additional code can be imported dynamically, etc. There was a thread about this the other day, but i cant locate it right now. :(