The PHP and HHVM drivers jailbreak the mongoc API and use several private symbols.
This means that the only way these drivers can be included in Linux standard distribution packages is if mongoc ships its private symbols, which implicitly makes those symbols public and part of the API. This clearly isn't a good idea and there are no intentions for mongoc to move all of its internal symbols into implicit public API that can never change or fixed.
The PHP team needs to compile a list of the internal symbols it uses so we can expose these symbols, one by one, in mongoc in the public API. This epic should contain all the symbols and track the progress of moving them into mongoc API, and removing them from phongo and hippo.