Is it possible for a macro to expand to nothing?

[Alan Mackenzie]

That is, not to a call to a null defun, but truly to nothing: i.e., the
ensuing code (as least, when byte compiled) will be identical to what it
would have been, had the macro invocation been omitted.

I want something like this:

(defmacro ifdef (condition &rest forms)
  "If the compile time CONDITION is non-nil, dump the FORMS to the
calling defun.  Otherwise do nothing."
  ......)

-- 
Alan Mackenzie (Nuremberg, Germany).