Re: Fwd: Errors when diff'ing arbitrary upstream remotes are not intuitive if git pull --all hasn't been done

From: Johan Herland <johan@herland.net>
Date: Oct 25, 2013, 07:25 UTC
Message-ID: <CALKQrgdfcDzq+M4Pi=DdbSPXCDCcXRtk6qV7qhvyHviJoJXA8A@mail.gmail.com>
In-Reply-To: <20131025071048.GA16856@sigill.intra.peff.net>

On Fri, Oct 25, 2013 at 9:10 AM, Jeff King <peff@peff.net> wrote:

Show 22 quoted lines

> On Fri, Oct 25, 2013 at 09:03:41AM +0200, Johan Herland wrote:
>>  1. Split the input on the first '/' into $remote/$branch, and use the
>> preceding part ($remote) as a potential remote name, and the following
>> part ($branch) as a potential branch name. (Although it is
>> theoretically possible to have remote names containing slashes, I
>> don't think anybody uses them, and we have considered disallowing
>> them, mainly because of this very issue: it makes "$remote/$branch"
>> parsing (even more) ambiguous)
>
> What I specifically meant is that this breaks with a remote like:
>
>   [remote "foo"]
>     fetch = +refs/heads/*:refs/remotes/bar/*
>
> The correct advice for "bar/branch" is to recommend "git fetch foo", and
> the correct advice for "foo/branch" is nothing at all.
>
> I know such config is unusual, but I thought there was a recent push for
> us to be accurate about finding the local side of remote tracking
> branches, rather than just assuming they start with "$remote". Maybe I
> am misremembering, though; I thought it was related to potentially
> shifting the default refspecs.

Obviously, you're right. Sorry about that, haven't had my morning coffee yet. :(

Show 9 quoted lines

> The procedure along those lines would be:
>
>   for each remote
>     for each fetch-refspec in remote
>       if refspec.rhs contains "refs/remotes/$failed_branch"
>         recommend "git fetch $remote"
>
> I was just wondering if we had something to make that "does this refspec
> contain this ref" part easier.

Yes, I found the following code in branch.c (added in 41c21f2), which does a similar thing. Might want to refactor that into something more general:

+static int check_tracking_branch(struct remote *remote, void *cb_data)
+{
+       char *tracking_branch = cb_data;
+       struct refspec query;
+       memset(&query, 0, sizeof(struct refspec));
+       query.dst = tracking_branch;
+       return !(remote_find_tracking(remote, &query) ||
+                prefixcmp(query.src, "refs/heads/"));
+}
+
+static int validate_remote_tracking_branch(char *ref)
+{
+       return !for_each_remote(check_tracking_branch, ref);
+}

Hope this helps,

...Johan

-- 
Johan Herland, <johan@herland.net>
www.herland.net