How to debug (potential) GC bugs?

[Martin Nowak via Digitalmars-d-learn]

On Saturday, 1 October 2016 at 00:06:05 UTC, Matthias Klumpp 
wrote:
> So, this problem is:
>  A) A compiler / DRuntime bug, or
>  B) A bug in my code (not) triggered by a certain compiler / 
> DRuntime

We actually did change druntime recently to no longer fail when 
using GC.free from a finalizer (will get ignored now). Maybe 
that's what fixed it for you w/ a newer version, but at a quick 
glance I haven't seen any freeing code in destructors.