Re: [PATCH 4/5] allow deepening of a shallow repository

> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
> 
> >> Although I am reasonably sure we can eventually make it work, it
> >> is very subtle and fragile -- somebody touching this code can
> >> easily break it.
> >
> > I fully agree. Even the OA did not understand the code fully ;-)
> >
> > How about adding "int force_reparse" to the signature of 
> > unregister_shallow()? (Just like we added "int cleanup" to 
> > get_merge_bases() to avoid pilot errors.)
> 
> I do not think that's where its fragility lies.  It is that any
> random place can later call parse_object() on the commit, after
> you elaborately pre-parsed it with shallow so that it appears to
> have fewer parents, with the expectation that nobody ever would
> clear the parsed bit and cause it to be reparsed again.  With
> that assumption, find_common() manipulated the shallow entry
> after setting that scheme up.  A mechanism to prevent the commit
> >from getting re-parsed would have made it more robust.