Re: [PATCH 0/4] Re: cherry-pick and 'log --no-walk' and ordering

From: Martin von Zweigbergk <martin.von.zweigbergk@gmail.com>
Date: Aug 13, 2012, 16:09 UTC
Message-ID: <CAOeW2eHprw73+zqVbJRird1eE7ayU_KjCUSoieYsGi1rbL5QBQ@mail.gmail.com>
In-Reply-To: <7vhas7fefs.fsf@alter.siamese.dyndns.org>

On Mon, Aug 13, 2012 at 12:17 AM, Junio C Hamano <gitster@pobox.com> wrote:

> y@google.com writes:
>
> [Administrivia: I somehow doubt y@google.com would reach you, and
> futzed with the To: line above]

:-( Sorry, sendemail.from now set. (I apparently answered "y" instead of just <enter> to accept the default.)

> I actually think --no-walk, especially when given any negative
> revision, that sorts is fundamentally a flawed concept (it led to
> the inconsistency that made "git show A..B C" vs "git show C A..B"
> behave differently, which we had to fix recently).

I completely agree.

> Would anything break if we take your patch, but without two
> possibilities to revs->no_walk option (i.e. we never sort under
> no_walk)?  That is, the core of your change would become something
> like this:

I also thought the sorting was just a bug. From what I understand by looking how the code has evolved, the sorting in the no-walk case was not intentional, but more of a consequence of the implementation. That patch you suggested was my first attempt and led me to find the broken cherry-pick test cases that I then fixed in patch 2/4. But, it clearly would break the test case in t4202 called 'git log --no-walk <commits> sorts by commit time'. So I started digging from there and found e.g.

http://thread.gmane.org/gmane.comp.version-control.git/123205/focus=123216

For convenience, I have pasted the commit message of the commit mentioned in that thread at the end of this email. So we would be breaking at least Johannes's use case if we changed it. I would think almost everyone who doesn't already know would expect "git rev-list A B" to list them in that order, so is a migration desired? Or just change the default for --no-walk from "sorted" to "unsorted" in git 2.0?

By the way, git-log's documentation says "By default, the commits are shown in reverse chronological order.", which to some degree is in support of the current behavior.

commit 8e64006eee9c82eba513b98306c179c9e2385e4e
Author: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Date:   Tue Jul 24 00:38:40 2007 +0100

    Teach revision machinery about --no-walk

    The flag "no_walk" is present in struct rev_info since a long time, but
    so far has been in use exclusively by "git show".

    With this flag, you can see all your refs, ordered by date of the last
    commit:

    $ git log --abbrev-commit --pretty=oneline --decorate --all --no-walk

    which is extremely helpful if you have to juggle with a lot topic
    branches, and do not remember in which one you introduced that uber
    debug option, or simply want to get an overview what is cooking.

    (Note that the "git log" invocation above does not output the same as

     $ git show --abbrev-commit --pretty=oneline --decorate --all --quiet

     since "git show" keeps the alphabetic order that "--all" returns the
     refs in, even if the option "--date-order" was passed.)

    For good measure, this also adds the "--do-walk" option which overrides
    "--no-walk".

    Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
    Signed-off-by: Junio C Hamano <gitster@pobox.com>