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From: Felipe Contreras <felipe.contreras@gmail.com>
To: Elijah Newren <newren@gmail.com>,
	Felipe Contreras <felipe.contreras@gmail.com>
Cc: "Sergey Organov" <sorganov@gmail.com>,
	"Junio C Hamano" <gitster@pobox.com>,
	"Johannes Sixt" <j6t@kdbg.org>, "Jeff King" <peff@peff.net>,
	"David Aguilar" <davvid@gmail.com>,
	"Bagas Sanjaya" <bagasdotme@gmail.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Denton Liu" <liu.denton@gmail.com>,
	"Git Mailing List" <git@vger.kernel.org>
Subject: Re: [PATCH 7/7] xdiff: make diff3 the default conflictStyle
Date: Sun, 13 Jun 2021 09:34:04 -0500	[thread overview]
Message-ID: <60c6175ca6840_41f2b208fc@natae.notmuch> (raw)
In-Reply-To: <CABPp-BGhaSJmqXFKpCVcUKexNXaa8sLEms-6q-qno7uETzGQ=A@mail.gmail.com>

Elijah Newren wrote:
> On Fri, Jun 11, 2021 at 2:05 PM Felipe Contreras
> <felipe.contreras@gmail.com> wrote:
> >
> > Elijah Newren wrote:
> > > On Fri, Jun 11, 2021 at 10:57 AM Felipe Contreras <felipe.contreras@gmail.com> wrote:
> >
> > > > Or just use the base of the virtual merge:
> > > >
> > > >   <<<<<<< HEAD
> > > >   D
> > > >   ||||||| merged common ancestors
> > > >   1
> > > >   =======
> > > >   C
> > > >   >>>>>>> C
> > >
> > > I think that implementing this choice would look like this (again, not
> > > compiled or tested and I'm not familiar with xdiff so take it with a
> > > big grain of salt):
> > >
> > >
> > > diff --git a/ll-merge.c b/ll-merge.c
> > > index 095a4d820e..dbc7f76951 100644
> > > --- a/ll-merge.c
> > > +++ b/ll-merge.c
> > > @@ -130,6 +130,8 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
> > >       memset(&xmp, 0, sizeof(xmp));
> > >       xmp.level = XDL_MERGE_ZEALOUS;
> > >       xmp.favor = opts->variant;
> > > +     if (git_xmerge_style >= 0 && opts->virtual_ancestor)
> > > +             xmp.favor = XDL_MERGE_FAVOR_BASE;
> >
> > The only time git_xmerge_style isn't >= 0 is when no merge style has
> > been configured by the user.
> 
> Yep, probably should have just been
> 
> +     if (opts->virtual_ancestor)
> +             xmp.favor = XDL_MERGE_FAVOR_BASE;
> 
> Though the difference doesn't matter a lot.  Since
> merge.conflictStyle=merge (which is the current default) doesn't
> display the contents from the merge base in a three-way content merge,
> setting xmp.favor to XDL_MERGE_FAVOR_BASE vs. leaving it as 0 for the
> recursive/intermediate merges won't generally end up affecting the end
> result.  It'd only matter for diff3 and zdiff3 users.

OK, so:

  if (git_xmerge_style > 0 && opts->virtual_ancestor)

> Going on a slight tangent, I think there's actually a related bug
> here.  We probably should not honor XDL_MERGE_FAVOR_{OURS,THEIRS} when
> opts->virtual_ancestor is true; that's just asking for trouble.  I
> think it'd paradoxically result in reversing the desired behavior
> (e.g. users would see what they'd consider XDL_MERGE_FAVOR_THEIRS
> behavior when they asked for XDL_MERGE_FAVOR_OURS) in some cases as a
> result.

Maybe write a test-case and find out?

> > In fact, I don't see why any style should change that desired behavior.
> > If you said there's issues with the "merge" style too, perhaps the above
> > will help for those cases too.
> >
> > > > We don't have to use diff3 all the way.
> > >
> > > Right, thus my mention in the other email to consider adding a
> > > XDL_MERGE_FAVOR_BASE -- which you then also mention here in your third
> > > option, and which I've now given at least a partial patch for.  Not
> > > sure if it's a crazy idea or a great idea, since I don't do very many
> > > criss-cross merges myself.
> >
> > I thought you meant as a separate configurable flag, not something done
> > by default.
> >
> > Now that I understand what you meant I think it could be a great idea.
> 
> If someone that does lots of criss-cross merges can comment on the
> idea, and agree that it's worth a shot, I can try to turn it into real
> patches.

I would flip the conditional: if nobody that does lots of criss-crosses
objects...

If we waited for a tiny minority of users to speak up before doing
something we migth wait forever.

> (I might even try to investigate the zdiff3 stuff too, which sounds
> like something I've wanted many times...but I'd really rather
> concentrate on merge-ort until its upstreaming is finished.)

Well, I just re-sent the patch:

https://lore.kernel.org/git/20210613143155.836591-1-felipe.contreras@gmail.com/

Cheers.

-- 
Felipe Contreras

  reply	other threads:[~2021-06-13 14:37 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-09 19:28 [PATCH 0/7] Make diff3 the default conflict style Felipe Contreras
2021-06-09 19:28 ` [PATCH 1/7] test: add merge style config test Felipe Contreras
2021-06-09 19:42   ` Eric Sunshine
2021-06-09 20:29     ` Felipe Contreras
2021-06-10  9:18   ` Phillip Wood
2021-06-10 13:26     ` Felipe Contreras
2021-06-10 14:54       ` Phillip Wood
2021-06-10 16:34         ` Felipe Contreras
2021-06-10 14:58       ` Phillip Wood
2021-06-10 16:47         ` Felipe Contreras
2021-06-11  9:19           ` Phillip Wood
2021-06-11 14:39             ` Felipe Contreras
2021-06-09 19:28 ` [PATCH 2/7] merge-tree: fix merge.conflictstyle handling Felipe Contreras
2021-06-09 19:28 ` [PATCH 3/7] notes: " Felipe Contreras
2021-06-09 19:28 ` [PATCH 4/7] checkout: " Felipe Contreras
2021-06-10  9:32   ` Phillip Wood
2021-06-10 14:11     ` Felipe Contreras
2021-06-10 14:50       ` Phillip Wood
2021-06-10 16:32         ` Felipe Contreras
2021-06-11  9:18           ` Phillip Wood
2021-06-11 14:34             ` Felipe Contreras
2021-06-11  9:18   ` Phillip Wood
2021-06-09 19:28 ` [PATCH 5/7] xdiff: rename XDL_MERGE_STYLE_DIFF3 Felipe Contreras
2021-06-10  9:21   ` Phillip Wood
2021-06-10 13:33     ` Felipe Contreras
2021-06-11  3:17     ` Junio C Hamano
2021-06-11 13:42       ` Felipe Contreras
2021-06-09 19:28 ` [PATCH 6/7] xdiff: simplify style assignments Felipe Contreras
2021-06-10  9:26   ` Phillip Wood
2021-06-10 13:50     ` Felipe Contreras
2021-06-09 19:28 ` [PATCH 7/7] xdiff: make diff3 the default conflictStyle Felipe Contreras
2021-06-10  6:41   ` Johannes Sixt
2021-06-10  7:53     ` Đoàn Trần Công Danh
2021-06-10 13:18       ` Felipe Contreras
2021-06-10 13:18     ` Felipe Contreras
2021-06-10 13:49     ` Jeff King
2021-06-10 16:00       ` Felipe Contreras
2021-06-10 16:31         ` Jeff King
2021-06-11  1:20       ` Junio C Hamano
2021-06-11  6:23         ` Johannes Sixt
2021-06-11  6:43           ` Junio C Hamano
2021-06-11  7:02             ` Johannes Sixt
2021-06-11  7:14               ` Junio C Hamano
2021-06-11 11:51                 ` Sergey Organov
2021-06-11 15:32                   ` Felipe Contreras
2021-06-11 15:52                     ` Sergey Organov
2021-06-11 16:36                       ` Felipe Contreras
     [not found]                     ` <CABPp-BHRQSF2_aYTBfpfnW4Bh3Hz7vLFj_QNGj8R4WeCS6_utw@mail.gmail.com>
2021-06-11 17:57                       ` Felipe Contreras
2021-06-11 19:02                         ` Elijah Newren
2021-06-11 21:05                           ` Felipe Contreras
2021-06-11 21:40                             ` Elijah Newren
2021-06-13 14:34                               ` Felipe Contreras [this message]
2021-06-11 16:41                   ` Johannes Sixt
2021-06-11 17:21                     ` Felipe Contreras
2021-06-11 17:40                       ` Sergey Organov
2021-06-11 18:10                         ` Felipe Contreras
2021-06-11 18:22                           ` Sergey Organov
2021-06-11 14:28                 ` Felipe Contreras
2021-06-11 14:25               ` Felipe Contreras
2021-06-11 16:53                 ` Johannes Sixt
     [not found]                 ` <CABPp-BH0aRiSUw03nSK6jHRNQ+zcpUzr6WjeJ5GpdUCqCKxbag@mail.gmail.com>
2021-06-11 17:32                   ` Felipe Contreras
2021-06-11 17:57                     ` Elijah Newren
2021-06-11 18:28                       ` Felipe Contreras
2021-06-11 14:20           ` Felipe Contreras
2021-06-11 14:09         ` Felipe Contreras
2021-06-10  9:40   ` Phillip Wood
2021-06-10 14:19     ` Felipe Contreras
2021-06-17 17:40 ` [PATCH 0/7] Make diff3 the default conflict style Phillip Wood
2021-06-17 18:24   ` Felipe Contreras

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