Re: [PATCH v2 3/7] packfile: extend `is_delta` field to allow for "unknown" state

> Patrick Steinhardt <ps@pks.im> writes:
> 
> > The `struct object_info::u::packed::is_delta` field determines whether
> > or not a specific object is stored as a delta. It only stores whether or
> > not the object is stored as delta, so it is treated as a boolean value.
> >
> > This boolean is insufficient though: when reading a packed object via
> > `packfile_store_read_object_info()` we know to skip parsing the actual
> > object when the user didn't request any object-specific data. In that
> > case we won't read the object itself, but will only look up its position
> > in the packfile. Consequently, we do not know whether it is a delta or
> > not.
> 
> This explains why you're introducing "unknown", but I'm having trouble
> understanding why we need distinction between ofs-delta and ref-delta?
> 
> (To any other reader: If you want to know what those two are, check
> "Deltified representation" in Documentation/gitformat-pack.adoc)

> > This isn't really an issue right now, as the check for an empty request
> > is broken. But a subsequent commit will fix it, and once we do we will
> > have the need to also represent an "unknown" delta state.
> >
> > Prepare for this change by introducing a new enum that encodes the
> > object type. We don't use the "unknown" state just yet, but will start
> > to do so in the next commit.
> 
> A little bit confusing this "next commit" is [PATCH 6/7], but that's a
> note to any other reader and not so much a nitpick worth addressing.