On Tuesday, 3 May 2016 at 16:44:32 UTC, Jack Stouffer wrote: > On Tuesday, 3 May 2016 at 16:15:27 UTC, Jeremy DeHaan wrote: >> I agree, but a precise heap scan should be the easiest part of this project. Rainer Schuetze has already implemented this and presented it at a dconf a few years ago(2013?). My plan is to use that since I know it works, and that frees up my time to focus on pretty much everything else. > > I don't remember all the details, but I'm pretty sure that Rainer, or maybe someone else, was talking about how a precise GC is not completely possible in D because D has unions. I am reading a paper on how one could use extra information about what was last assigned to a union in order to scan them precisely. I haven't read the whole thing yet, but it looks like it could be done. Not sure if it is something I can get to in the course of my project though. Scanning only unions conservatively is still pretty good.