Subject: Re: [PATCH v14 14/27] bisect--helper: `bisect_next` and `bisect_auto_next` shell function in C

From: Junio C Hamano <[email-masked]>
Date: Tue, 30 Aug 2016 12:33:55 -0700

Pranit Bauva <[email-masked]> writes:

> This is a very tricky one. I have purposely not included this after a
> lot of testing. I have hand tested with the original git and with this
> branch. The reason why anyone wouldn't be able to catch this is
> because its not covered in the test suite. I am including a patch with
> this as an attachment (because I am behind a proxy right now but don't
> worry I will include this as a commit in the next series). The
> original behaviour of git does not clean the bisect state when this
> situation occurs.

"We sometimes clean and we sometimes don't and this follows the
original" may be a valid justification but it is not a very useful
explanation.  The real issue is if not cleaning is intended (and if
so why; otherwise, if it is clear that it is simply forgotten, we
can just fix it in the series as a follow-up step).

If not cleaning in some cases (but not others) is the right thing,
at least there needs an in-code comment to warn others against
"fixing" the lack of cleanups (e.g. "don't clean state here, because
the caller still wants to see what state we were for this and that
reason").

>>> +     if (bisect_next_check(terms, terms->term_good.buf))
>>> +             return -1;
>>
>> Mental note.  The "autostart" in the original is gone.  Perhaps it
>> is done by next_check in this code, but we haven't seen that yet.
>
> This will be added back again in a coming patch[1].

In other words, this series is broken at this step and the breakage
stay with the codebase until a later step?

I do not know if reordering the patches in the series is enough to
fix that, or if it is even worth to avoid such a temporary breakage.
It depends on how serious the circularity is, but I would understand
if it is too hard and not worth the effort (I think in a very early
review round some people advised against the bottom-up rewrite
because they anticipated this exact reason).  At least the omission
(and later resurrection) needs to be mentioned in the log so that
people understand what is going on when they later need to bisect.

Thanks.