Re: [RFC 3/3] refspec: add support for negative refspecs

>
> On Tue, Aug 18, 2020 at 10:41 AM Jeff King <peff@peff.net> wrote:
> > Hmm. I think the behavior we'd want is something like:
> >
> >   # make sure the other side has three refs
> >   git branch prune/one HEAD
> >   git branch prune/two HEAD
> >   git branch prune/three HEAD
> >   git push dst.git refs/heads/prune/*
> >
> >   # now drop two of ours, which are eligible for pruning
> >   git branch -d prune/one
> >   git branch -d prune/two
> >
> >   # push with pruning, omitting "two"
> >   git push --prune dst.git refs/heads/prune/* ^refs/heads/prune/two
> >
> >   # we should leave "two" but still deleted "one"
> >   test_write_lines one three >expect
> >   git -C dst.git for-each-ref --format='%(refname:lstrip=3)' refs/heads/prune/ >actual
> >   test_cmp expect actual
> >
> > I.e., the negative refspec shrinks the space we're considering pruning.
> > And we'd probably want a similar test for "fetch --prune".
> >
> > I just tried that, though, and got an interesting result. The push
> > actually complains:
> >
> >   $ git push --prune dst.git refs/heads/prune/* ^refs/heads/prune/two
> >   error: src refspec refs/heads/prune/two does not match any
> >   error: failed to push some refs to 'dst.git'
> >
> > For negative refspecs, would we want to loosen the "must-exist" check?
> > Or really, is this getting into the "are we negative on the src or dst"
> > thing you brought up earlier? Especially with --prune, what I really
> > want to say is "do not touch the remote refs/heads/two".
> >
> > We can get work around it by using a wildcard:
> >
> >   $ git push --prune dst.git refs/heads/prune/* ^refs/heads/prune/two*
> >   To dst.git
> >    - [deleted]         prune/one
> >
> > So it works as I'd expect already with your patch. But I do wonder if
> > there are corner cases around the src/dst thing that might not behave
> > sensibly.
> >
>
> Hmm. So this raises a good point. I added a variation of this test
> where I used separate names for the source and destination. It looks
> like with the current implementation, negative refspecs always apply
> to the destination.