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From: Junio C Hamano <>
To: Jonathan Tan <>
Subject: Re: [PATCH] apply: when -R, also reverse list of sections
Date: Tue, 20 Oct 2020 13:06:19 -0700	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <> (Jonathan Tan's message of "Tue, 20 Oct 2020 12:12:06 -0700")

Jonathan Tan <> writes:

>> But I have to wonder if it breaks the support for (arguably outside
>> the Git usecase) input that has more than one patch that touches the
>> same path to blindly reverse the order of all patches
> Sorry for getting back to this so late.
> The only other case I can think of (besides symlink<->file) is
> directory<->file, and even in that case, I think blindly reversing the
> order still works.
> If a more sophisticated rearrangement was needed, I would think that
> even applying the patches in the forward direction (that is, without
> "-R") wouldn't work, since Git is sensitive to the order of the patches.
> So I don't think we need to support such input (since they wouldn't work
> in the forward direction anyway).

I wish you told that to those who added fn_table kludge to apply.c
back when they did so.  They apparently wanted to have a patch that
has more than one "diff --git a/hello.c b/hello.c" that talks about
the same file applied with a single invocation of "git apply".
Perhaps what they did is already broken with "apply -R", and blind
reversal of everything magically makes it work?  Or what they did
already works with "apply -R" and your blind reversal would break,
unless you undo what they did?

>> (instead of
>> the obvious implementation of the fix for the above stated problem
>> --- i.e. make sure the first patch is a deletion of a symlink and
>> what immediately follows is a creation of a regular file, and swap
>> them only in such a case).
> This would make patch application more robust, but I still appreciate
> the relative simplicity of the existing approach

I'd rather want to see that we keep the normal cases simple,
i.e. majority parts of a patch with "apply -R" that did *not* have
to futz with the application order will keep what we do, and if
there are tricky cases like typechange diff, only special case them.


  reply	other threads:[~2020-10-20 20:06 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-28 21:20 [PATCH] apply: when -R, also reverse list of sections Jonathan Tan
2020-09-28 22:07 ` Junio C Hamano
2020-10-20 19:12   ` Jonathan Tan
2020-10-20 20:06     ` Junio C Hamano [this message]
2020-10-20 20:50       ` Junio C Hamano
2020-10-20 21:36         ` Jonathan Tan
2020-10-20 21:48           ` Junio C Hamano
2020-10-20 22:04             ` [PATCH v2] " Jonathan Tan

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