How can I properly import functions from gcx in object.di?

[Antti-Ville Tuunainen]

I'm working on the precise gc patches. I now have a bunch of 
templates and all the other infrastructure, but what's holding me 
back is that I don't quite understand the .di files.

In order for user-defined datastructures to instantiate the 
correct templates, the template code needs to live (/be imported 
into) the object.di file. However, for any kind of efficiency, 
the templates also need to be able to directly call functions 
and/or access the state from src/gc/gcx.d. I cannot just import 
it, because it won't be available during (user code) compilation. 
What is the correct approach?

Currently, I'm leaning on creating a new public gc.di (or 
similar), with functions to scan ranges and single pointers, and 
add implementations of those to the gcx side. Is this the correct 
way forward?