hide-ifdefs
hide-ifdefs is an interactive compiled Lisp function in `hideif.el
'.
(hide-ifdefs &optional NOMSG)
Hide the contents of some #ifdefs.
Assume that defined symbols have been added to `hide-ifdef-env'.
The text hidden is the text that would not be included by the C
preprocessor if it were given the file with those symbols defined.
With prefix command presents it will also hide the #ifdefs themselves.
Turn off hiding by calling `show-ifdefs'.