Re: [PATCH v3 0/3] Maintenance: adapt custom refspecs

[Tom Saeger <tom.saeger@oracle.com>]

On Mon, Apr 12, 2021 at 12:24:27PM -0500, Tom Saeger wrote:
> On Mon, Apr 12, 2021 at 11:48:09AM -0500, Tom Saeger wrote:
> > On Sat, Apr 10, 2021 at 06:35:40PM -0700, Junio C Hamano wrote:
> > > "Derrick Stolee via GitGitGadget" <gitgitgadget@gmail.com> writes:
> > > 
> > > >  * The fix is almost completely rewritten as an update to 'git fetch'. See
> > > >    the new PATCH 2 for this update.
> > > 
> > > I do agree that it gives us the most flexibility there with nice
> > > encapsulation.  Nobody other than "git fetch" needs to know how it
> > > computes which remote refs are fetched given the real pathspec, and
> > > the only thing the caller with "--prefetch" is interested in is that
> > > the prefetch operation would not contaminate the remote-tracking
> > > refs.
> > > 
> > > Great idea.  I wish I were the one who thought of it first ;-)
> > 
> > Yes - this simplifies things greatly!
> > 
> > I do have one case that fails prefetch though.
> > It's a case where all the remote's fetch configs are filtered out.
> > 
> > Example:
> > 
> > 	[remote "pr-924"]
> > 	    url = https://github.com/gitgitgadget/git
> > 	    fetch = +refs/tags/pr-924/derrickstolee/maintenance/refspec-v3
> > 	    skipfetchall = true
> > 	    tagopt = --no-tags
> > 
> > 
> > In this case, running `git fetch pr-924` will fetch and update
> > FETCH_HEAD, but running with maintenance prefetch task results in:
> > 
> > fatal: Couldn't find remote ref HEAD
> > error: failed to prefetch remotes
> > error: task 'prefetch' failed
> > 
> > I tracked this down a bit, but don't have a suggestion how to fix it.
> 
> This ugly hack fixes this failure.  I'll keep staring at it.
> 
> 
> diff --git a/builtin/fetch.c b/builtin/fetch.c
> index 30856b442b79..6489ce7d8d3b 100644
> --- a/builtin/fetch.c
> +++ b/builtin/fetch.c
> @@ -508,6 +508,9 @@ static struct ref *get_ref_map(struct remote *remote,
>         if (remote)
>                 filter_prefetch_refspec(&remote->fetch);
> 
> +       if (prefetch && !rs->nr && remote && !remote->fetch.nr)
> +               return NULL;
> +
>         if (rs->nr) {
>                 struct refspec *fetch_refspec;
> 
> --
> 

Less ugly fix...

diff --git a/builtin/fetch.c b/builtin/fetch.c
index 30856b442b79..5fbffbd17d7d 100644
--- a/builtin/fetch.c
+++ b/builtin/fetch.c
@@ -576,6 +576,8 @@ static struct ref *get_ref_map(struct remote *remote,
                        if (has_merge &&
                            !strcmp(branch->remote_name, remote->name))
                                add_merge_config(&ref_map, remote_refs, branch, &tail);
+               } else if (prefetch) {
+                       ;
                } else {
                        ref_map = get_remote_ref(remote_refs, "HEAD");
                        if (!ref_map)
--

Other ideas?


> 
> 
> > 
> > builtin/fetch.c `get_ref_map` makes two calls to `filter_prefetch_refspec`,
> > one for 'rs' and another for 'remote->fetch'.
> > 
> > `filter_prefetch_refspec` works and filters out the above fetch config.
> > This correctly yields condition
> > `rs->nr == 0` and `remote->fetch.nr == 0`
> > 
> > Later a call is made to `get_remote_ref(remote_refs, "HEAD")` which
> > fails, leading to `fatal: Couldn't find remote ref HEAD`
> > 
> > Should this be expected, or should this now be special-cased for 'prefetch'
> > somehow?
> > 
> > Regards,
> > 
> > --Tom