From: Junio C Hamano <gitster@pobox.com>
To: Kevin Daudt <me@ikke.info>
Cc: git@vger.kernel.org
Subject: Re: [PATCH v4] rev-list: refuse --first-parent combined with --bisect
Date: Wed, 11 Mar 2015 13:13:48 -0700 [thread overview]
Message-ID: <xmqqsidb5m2r.fsf@gitster.dls.corp.google.com> (raw)
In-Reply-To: <20150311184512.GB5442@vps892.directvps.nl> (Kevin Daudt's message of "Wed, 11 Mar 2015 19:45:12 +0100")
Kevin Daudt <me@ikke.info> writes:
> On Tue, Mar 10, 2015 at 04:12:18PM -0700, Junio C Hamano wrote:
>
>> What does such a command line _mean_? It tells us this:
>>
>> Define a set by having the "bad" ref as a positive end, and
>> having all the "good" refs as negative (uninteresting) boundary.
>>
>> That is a way to show commits that are reachable from the bad one
>> and excluding the ones that are reachable from any of the known-good
>> commits. The area of the graph in the current bisection that
>> contains suspect commits.
>>
>> Now, what does it mean to pull only the first-parent chain starting
>> from the bad one in such a set in the first place? What does the
>> resulting set of commits mean?
>
> In that case it will leave out any merged in branches.
Needs a bit more thinking (hint: branches merged into *what*?).
> I recalled reading something about this. Searching found me the GSoC
> idea:
>
> When your project is strictly "new features are merged into trunk,
> never the other way around", it is handy to be able to first find a
> merge on the trunk that merged a topic to point fingers at when a
> bug appears, instead of having to drill down to the individual
> commit on the faulty side branch.
>
> So there is definitely a use case for --bisect --first-parent, which
> would show you those commits that would be part of the bisection.
Step back and think why "git bisect --first-parent" is sometimes
desired in the first place.
It is because in the regular bisection, you will almost always end
up on a commit that is _not_ on the first-parent chain and asked to
check that commit at a random place on a side branch in the first
place. And you mark such a commit as "bad".
The thing is, traversing from that "bad" commit that is almost
always is on a side branch, following the first-parent chain, will
not be a useful history that "leaves out any merged in branches".
When "git bisect --first-parent" feature gets implemented, "do not
use --first-parent with --bisect" limitation has to be lifted
anyway, but until then, not allowing "--first-parent --bisect" for
"rev-list" but allowing it for "log" does not buy our users much.
The output does not give us a nice "show me which merges on the
trunk may have caused the breakage to be examined with the remainder
of this bisect session".
So, yes, there is a use case for "log --bisect --first-parent", once
there is a working "bisect --first-parent", but not until then, the
command is not useful, I would think.
next prev parent reply other threads:[~2015-03-11 20:13 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-03 14:19 [BUG] Segfault with rev-list --bisect Troy Moure
2015-03-04 5:33 ` Jeff King
2015-03-04 23:44 ` Junio C Hamano
2015-03-05 2:15 ` Troy Moure
2015-03-07 21:31 ` [PATCH] rev-list: refuse --first-parent combined with --bisect Kevin Daudt
2015-03-07 23:13 ` Kevin Daudt
2015-03-08 8:00 ` Junio C Hamano
2015-03-08 14:18 ` [PATCH v2] " Kevin Daudt
2015-03-08 15:02 ` [PATCH v3] " Kevin Daudt
2015-03-08 15:03 ` Kevin Daudt
2015-03-08 21:58 ` Eric Sunshine
2015-03-09 11:57 ` Kevin Daudt
2015-03-09 20:56 ` [PATCH v4] " Kevin Daudt
2015-03-10 22:09 ` Junio C Hamano
2015-03-10 22:55 ` Kevin Daudt
2015-03-10 23:12 ` Junio C Hamano
2015-03-11 18:45 ` Kevin Daudt
2015-03-11 20:13 ` Junio C Hamano [this message]
2015-03-16 16:33 ` Kevin Daudt
2015-03-16 18:53 ` Junio C Hamano
2015-03-16 20:25 ` Philip Oakley
2015-03-16 21:05 ` Junio C Hamano
2015-03-17 16:09 ` Christian Couder
2015-03-17 18:33 ` Junio C Hamano
2015-03-17 19:49 ` Christian Couder
2015-03-17 20:46 ` Junio C Hamano
2015-03-18 10:36 ` Christian Couder
2015-03-19 23:51 ` Philip Oakley
2015-03-20 13:02 ` Scott Schmit
2015-03-19 22:14 ` [PATCH v5] " Kevin Daudt
2015-03-19 22:43 ` Junio C Hamano
2015-03-21 22:01 ` Kevin Daudt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: http://vger.kernel.org/majordomo-info.html
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=xmqqsidb5m2r.fsf@gitster.dls.corp.google.com \
--to=gitster@pobox.com \
--cc=git@vger.kernel.org \
--cc=me@ikke.info \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://80x24.org/mirrors/git.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).