Re: [PATCH v2 11/25] object_array_remove_duplicates(): rewrite to reduce copying

Michael Haggerty [off-list ref] writes:

quoted

The only caller of remove-duplicates is bundle.c, which gets many
starting points and end points from the command line and tries to be
nice by removing obvious duplicates, e.g.

	git bundle create t.bundle master master

but I think its logic of deduping is wrong.  It runs dwim_ref() on
the incoming refs after the remove-duplicates call, so

	git bundle create t.bundle master heads/mater

will end up with two copies of refs/heads/master.  To fix it, the
code must dedup the result of running dwim_ref(), and at that point,
there is no reason to call object_array_remove_duplicates().

That sounds reasonable.

I poked around this code a bit to understand what is going on, and it
occurred to me that the object_array can include both positive and
negative references, right?  And yet object_array_remove_duplicates()
only considers names, not flags.  So it seems to me that if the deduping
code would see the same reference twice, once positive and once
negative, then it would throw an arbitrary one of them out, which would
be wrong.

But I couldn't provoke this situation, so perhaps setup_revisions()
already specially treats combinations like "master ^master"?  (If that's
true then why? and wouldn't it get confused by "master ^heads/master"?)

With "git bundle create t.bundle ^master master", you see two
entries in revs.pending.objects[] but they are the same object and
is already marked as uninteresting, so you will not see 'master' in
the result.

This parsing loop predates the more recent revs->cmdline mechanism,
that treats these two command line arguments as separate entities,
so that we can more reliably tell what the real end-user input is.