On Sun, Nov 22, 2020 at 10:46:41AM -0600, Felipe Contreras wrote:
> Since commit 9ba89f484e git learned how to push to a remote branch using
> the source @, for example:
>
> git push origin @:master
>
> However, if the right-hand side is missing, the push fails:
>
> git push origin @
Yeah, I think this probably makes sense. I find the "@:master" refspec a
bit weird, but it is a natural consequence of parsing "@" on the LHS as
an arbitrary object to lookup (not a ref).
I did find the implementation a little curious:
> - item->src = xstrndup(lhs, llen);
> + if (llen == 1 && *lhs == '@')
> + item->src = xstrdup("HEAD");
> + else
> + item->src = xstrndup(lhs, llen);
We already know we are parsing the LHS, so why must we expand a bare @,
whereas we do not in "@:master". The answer is that the "@" is not
expanded until later, and parse_refspec() gets unhappy that "@" is also
the implicit value for the RHS.
This also means that:
git push origin @:foo
will now work when "foo" doesn't exist on the remote (if we find no
match on the remote, we guess how it should be fully qualified; one of
our heuristics involves seeing that HEAD points to a branch, and
therefore the other side should be a branch, too).
> It is obvious what is the desired behavior, and allowing the push makes
> things more consistent.
This same code is used by fetch, as well. There "git fetch origin
@:master" does not work at all now. This would make that work (to fetch
the remote HEAD into master), along with "git fetch origin @" (into
FETCH_HEAD only). Both seem sensible, and I cannot think of any other
reasonable meaning for them.
> ---
> refspec.c | 5 ++++-
> t/t5511-refspec.sh | 2 ++
> t/t5516-fetch-push.sh | 9 +++++++++
> 3 files changed, 15 insertions(+), 1 deletion(-)
Would we want to cover the extra cases I mentioned above (@:foo, and the
two fetches), as well?
I wondered if there was a good place to mention this in the refspec
documentation, but it may just be an obvious fallout of the "@ is a
shortcut for HEAD" definition in gitrevisions(7). The only change is
that we're resolving the shortcut sooner so that more code can take
advantage of it.
-Peff
