a warning to implement

[Robert Dewar]

<<Concluding the discussion on the ML, I can say that it's desirable to
have compiler emit the warning when it is run with `-Wall', and, of
course, there should be option for turning off the very warning.
>>

well I see nothing special about this warning, it is just one particular
case of accessing a variable before it has a defined value, and that is
a reasonable thing to warn about in general.