From: Junio C Hamano <gitster@pobox•com>
To: Christian Couder <chriscool@tuxfamily•org>
Cc: Johannes Schindelin <Johannes.Schindelin@gmx•de>,
Michael Haggerty <mhagger@alum•mit.edu>,
Jeff King <peff@peff•net>,
git@vger•kernel.org,
Linus Torvalds <torvalds@linux-foundation•org>
Subject: Re: [PATCH] bisect: error out when given any good rev that is not an ancestor of the bad rev
Date: Mon, 30 Jun 2008 15:48:49 -0700 [thread overview]
Message-ID: <7vy74mtu7i.fsf@gitster.siamese.dyndns.org> (raw)
In-Reply-To: <7v3amuv8yg.fsf@gitster.siamese.dyndns.org> (Junio C. Hamano's message of "Mon, 30 Jun 2008 15:44:55 -0700")
Junio C Hamano <gitster@pobox•com> writes:
> Christian Couder <chriscool@tuxfamily•org> writes:
>
>> Before this patch "git bisect" doesn't really work when it is given
>> some good revs that are siblings of the bad rev.
>>
>> For example if there is the following history:
>>
>> A-B-C-D
>> \E-F
>>
>> and we launch "git bisect start D F" then only C and D will be
>> considered as possible first bad commit. This is wrong because A, B and
>> E may be bad too if the bug exists everywhere except in F that fixes it.
>
> Please don't.
>
> bisect is about finding a single regression by partitioning the graph into
> older good section and newer bad section with a *single* "first bad
> commit".
>
> Your "this could also be possible" scenario is already outside the
> realm. You are assuming A, B and F is good, and D is bad. But if E is
> bad, then that breakage cannot possibly affect the transition between B
> and D from good to bad (E cannot break D), so C must *also* be bad.
... which means you are dealing with *two* breakages. That's outside what
bisect deals with.
And this does not need to have forked development. If the graph were like
this:
A-B-C-D-E-F
and if F is bad and B is good, with your logic, after checking that D is
already bad, we cannot discount E --- after somehow fixing D, we _might_
also be introducing another breakage with E. You cannot even check for
that anyway, but the logic is the same.
next prev parent reply other threads:[~2008-06-30 22:50 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-30 22:42 [PATCH] bisect: error out when given any good rev that is not an ancestor of the bad rev Christian Couder
2008-06-30 22:44 ` Junio C Hamano
2008-06-30 22:48 ` Junio C Hamano [this message]
2008-06-30 23:16 ` Christian Couder
2008-06-30 23:27 ` Junio C Hamano
2008-06-30 23:32 ` Junio C Hamano
2008-06-30 23:42 ` Junio C Hamano
2008-06-30 23:46 ` Christian Couder
2008-06-30 23:52 ` Junio C Hamano
2008-07-01 0:20 ` Christian Couder
2008-07-01 1:13 ` Junio C Hamano
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