enable libc++ debug checks?

Forgive me if I missed this in some documented place (which I couldn’t find with a cursory search), but I was wondering if it is possible to enable any debug checks for libc++ STL. After peeking in the headers I tried:


However this leads to build errors (‘__get_db undeclared’). If this is work in progress, is there a rough expected time when these checks will be completed?