Subject: Re: What's cooking in git.git (Feb 2014, #06; Wed, 19)

From: Junio C Hamano <[email-masked]>
Date: Mon, 24 Feb 2014 08:57:23 -0800

Max Horn <[email-masked]> writes:

> On 21.02.2014, at 19:04, Junio C Hamano <[email-masked]> wrote:
>
>>  Isn't it possible for some helpers to _do_ want to
>> tell us that it did not have to force after all by _not_ saying
>> "forced update" and overwrite ->forced_update with zero?
>
> Yes to the first part, no to the last bit: Yes, a transport helper
> can (and frequently does) tell us that no force happened -- by not
> saying "forced update".
> ...
>>  How do we tell helpers that do want to do so apart from other
>> helpers that say "forced update" only when they noticed they are
>> indeed forcing?
>
> I am not completely sure I even understand that bit?

I think I phrased it too imprecisely.

If nobody even knew about the "forced update" before hg helper, then
they by definition do not wish to overwrite, of course.  But I was
worried if we are closing the door for this possible scenario:

 * the calling side sets ref->forced_update to true before invoking
   the helper, knowing that this update is not fast-forward; and

 * the helper does a "magic" (after all, we are talking with an
   external mechanism, which may be a different SCM like darcs) to
   rebase our change on top of the history that the other side
   already have, and makes it a fast-forward, non-forced push.

Such a helper would want a way to say "You may have thought that
this does not fast-forward, but the push result ended up to be a
fast-forward update", and if we wanted to support that, one thing we
may need to allow it to do is to reset ref->forced_update to zero.

But I think I was worried too much into the future---I agree that
the code can stay as you proposed until such a remote-helper needs
more support, because "overwrite with zero" is necessary but is
probably not sufficient---it also may need to be able to tell us
what the final resulting commit of the push is, for example.