Stefan Xenos <sxenos@xxxxxxxxxx> writes: >> And the other half is that while I consider the "origin" thing is >> unnecessary for the above reasons, having it means we need to not >> just transfer the history reading to aa7ce555 and d664309ee (which >> are necessary anyway while we have histories to transplant from >> d664309ee to aa7ce555) but also have to pull in the history leading >> to 7e1bbcd and we cannot discard it. > > I'll assume that by "history" you're referring to the change graph > (the metacommits) and not the branches (the commits), which would have > no origin edges or connection between replacements. I meant the project's history, not the meta-graph thing. By having a "this was cherry-picked from that commit" in a commit that is not GC'ed, the original commit that has no longer have any relevance (because the newer one that is the result of the cherry-pick is the surviving version people will be building on) is kept reachable. It is very much delierate that "cherry-pick -x" does not make the "origin" reachable and merely notes it in the human readable form that is ignored by the reachablity machinery. > If the user has kept a change around in their metas namespace, it's an > indication that they (or their collaborators) are still working on it > and want its history to be retained. This is where we differ. If commit X was rewritten (perhaps with help from change cherry-picked from commit Z, or without any) to produce Y, I do agree that it would be logical to keep X around until every dependent commit on it are migrated to be on top of Y. But we do not need Z to transplant what used to be on X on top of Y, do we? So I do agree that in such a situation they want the relevant parts of the history retained, but I do not agree that "origin" is among them. Side note. As long as we have commits yet to be migrated to be on Y that still is on X, ew do not need the meta-commit to be protecting from getting GC'ed, as X is reachable from these "need to be updated" branch tips anyway. What we gain from extra reachability brought in by the meta commits is that by fetching the "change", we get Y (and its anestors), even if we are not following any branch that contains it, so that we can migrate those that are still based on X to it.
