Re: [PATCH v4 3/5] unpack-trees: optimize walking same trees with cache-tree

> > +      *
> > +      * D/F conflicts and higher stage entries are not a concern
> > +      * because cache-tree would be invalidated and we would never
> > +      * get here in the first place.
> > +      */
> > +     for (i = 0; i < nr_entries; i++) {
> > +             struct cache_entry *tree_ce;
> > +             int len, rc;
> > +
> > +             src[0] = o->src_index->cache[pos + i];
> > +
> > +             len = ce_namelen(src[0]);
> > +             tree_ce = xcalloc(1, cache_entry_size(len));
> > +
> > +             tree_ce->ce_mode = src[0]->ce_mode;
> > +             tree_ce->ce_flags = create_ce_flags(0);
> > +             tree_ce->ce_namelen = len;
> > +             oidcpy(&tree_ce->oid, &src[0]->oid);
> > +             memcpy(tree_ce->name, src[0]->name, len + 1);
> > +
> > +             for (d = 1; d <= nr_names; d++)
> > +                     src[d] = tree_ce;
> > +
> > +             rc = call_unpack_fn((const struct cache_entry * const *)src, o);
>
> I don't fully understand why this is still necessary since "we detect
> that all trees are the same as cache-tree at this path."  I do know
> (because I tried it :)) that if we don't actually call the unpack
> function the patch fails a bunch of tests so clearly something important
> is being missed.