Re: [PATCH v4] revision: add `--ignore-missing-links` user option

From: Karthik Nayak <karthik.188@gmail.com>
Date: Sep 24, 2023, 16:14 UTC
Message-ID: <CAOLa=ZThB0DrRKg98tr7JLu8yPRyDXe_ngkpS3ZfesHQ-f1DLg@mail.gmail.com>
In-Reply-To: <xmqq5y435obx.fsf@gitster.g>

On Thu, Sep 21, 2023 at 9:16 PM Junio C Hamano <gitster@pobox.com> wrote:

Show 19 quoted lines

>
> Karthik Nayak <karthik.188@gmail.com> writes:
>
> > I was thinking about this, but mostly didn't do this, because the
> > interaction with `--missing` is only for non-commit
> > objects. Because for missing commits, `--ignore-missing-links`
> > skips the commit and the value of `--missing` doesn't make any
> > difference.
>
> Hmph, somehow that smells like an existing bug.  So does the "trees
> are not shown by --missing=print, and show_object() is never called
> for missing objects unless they are blobs" you mention.  When the
> user asks "instead of dying, list them so that I can ask around and
> fetch them to repair this repository", shouldn't we do just that?
>
> I wonder if these bugs are something people may be taking advatage
> of and cannot be fixed retroactively?  If we can fix these and nobody
> complains, that would give us the ideal outcome, I would think.
>

Let me prefix with saying that I was partly wrong. `--missing` does work for trees, only that it's ineffective when used along with the `ignore_missing_links` bit.

But for commits, `--missing` was never configured to work with. I did a quick look at the code, we can do something like this for commits too, i.e. add support for the `--missing` option. We'll have to add a new flag (maybe MISSING) so it can be set during within `repo_parse_commit_gently` so we can parse this as a missing object in rev-list.c and act accordingly.

It would invalidate this patch series in some sense. But I'm okay with that. Does that sound good to you?