Re: [PATCH] gc --auto: warn garbage collection happens soon

> Especially now that prune has learned about progress reporting, it's
> easy to see in "git gc" that the "Counting objects" phase of the repack
> and the connectivity search in prune are counting the same objects.  It
> would obviously be easy to just dump the set of sha1s in packed binary
> format, and let git-prune reference that.
>
> But it doesn't work in the general case. Running "git gc" will repack
> everything, and so it looks at all reachable objects. But "git gc
> --auto" will typically do an incremental pack (unless you have too many
> packs), which means its counting objects phase only looks at part of
> the graph.  So that result can't be used for object reachability, since
> many objects won't be marked[1].