Does PURIFY get rid of the warnings by suppressing them, or by disabling code temporarily for debugging purposes (since it mentions macros)? The FAQ seems unclear on that point.
https://github.com/joyent/node/search?q=PURIFY
Specifically it is these two files:-
https://github.com/joyent/node/blob/5fcd6e40385f45bc90916893...
https://github.com/joyent/node/blob/c20b209dbb7e2f3ac8a75a87...
In the first it just does a memset of the buffer so that the values are not unset.
In the second it doesn't use a (possibly only partially filled) buffer as a source of entropy.