RE: [sv-bc] Mantis 1090: `undefineall

 > Probably the directive should undefine only the `define macros, because
 > otherwise the directive won't be too useful (since once the command line
 > macros are undefined, there will be no way to define them again). In
 > that case, it may be better to change the wording to refer to `define
 > explicitly, to avoid ambiguity.

I would say the opposite.  You *might* want to have a design
whose behavior is independent of any command line -define
switches.  You could do this by first `undefining any and
all macros first.

Paul