Re: [PATCH/RFC] commit: warn when a new commit is dated before its parent

From: Yashwanth Sai <ysaimuppineni789@gmail.com>
Date: Sep 19, 2026, 15:46 UTC
Message-ID: <CABykktEd-rn04SeFQqqpnB0npDaSxVLx5vQ1f9LmJGJpVckv6w@mail.gmail.com>
In-Reply-To: <aq6j2yg16L2iNHoR@fruit.crustytoothpaste.net>

Thanks for looking at it, and for the pointer.

You're right. I hadn't read the AI section of SubmittingPatches before sending, and I should have. The patch was written with AI assistance to the extent that I can't honestly claim it as my own work under the DCO, so I'm withdrawing it. I've closed the pull request.

Sorry for the noise. If I come back to this, I'll write it myself.

On Sat, Sep 19, 2026 at 8:32 PM brian m. carlson <sandals@crustytoothpaste.net> wrote:

Show 45 quoted lines

>
> On 2026-09-19 at 14:04:25, Yashwanth Sai via GitGitGadget wrote:
> > From: Yashwanth Sai <ysaimuppineni789@gmail.com>
> >
> > Git writes whatever the clock says into the commit object and validates
> > nothing: a commit dated years in the future, or earlier than its own
> > parent, is accepted silently. "git fsck --strict" does not object either,
> > since fsck's badDate and badDateOverflow checks are purely syntactic.
> >
> > That would be harmless if history traversal did not assume commit dates
> > are non-decreasing, but it does. "git log --since" stops walking at the
> > first commit older than the cutoff, so a single out-of-order date hides
> > every commit behind it:
> >
> >       $ git log --pretty='%cd %s' --date=short
> >       2026-09-25 C3 - inside the window
> >       2026-09-01 C2 - outside the window
> >       2026-09-20 C1 - inside the window
> >
> >       $ git log --pretty='%cd %s' --date=short --since=2026-09-13
> >       2026-09-25 C3 - inside the window
> >
> > C1 is inside the window and silently missing. This is understood --
> > 96697781e0 (revision: add "--since-as-filter" option, 2022-07-19) added
> > an opt-in traversal mode for it -- but nothing tells the person whose
> > clock caused it, at the moment they could still fix it cheaply.
> >
> > Warn at commit time when the new commit's date precedes a parent's, gated
> > on a new advice.clockSkew setting. Warning rather than refusing is
> > deliberate: only the committer can tell whether their clock or the
> > parent's is the wrong one. Once the commit is published the date is part
> > of its object name, and correcting it means rewriting every descendant,
> > so the warning is worth little later and quite a lot now.
>
> I think such a change is useful and it certainly has been discussed on
> the list quite a bit.
>
> > Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>
>
> I don't think this is allowed by the `ai` section of
> `Documentation/SubmittingPatches`. I wouldn't be opposed to seeing such
> a patch if it were not produced in any way by AI, though.
> --
> brian m. carlson (they/them)
> Toronto, Ontario, CA

-- 
Yours Sincerely,
M Yashwanth Sai
9491363067