Re: difftool sends malformed path to exernal tool on Windows

From: David Aguilar <davvid@gmail.com>
Date: Mar 16, 2014, 07:27 UTC
Message-ID: <CAJDDKr7=OVF0eJQFjFqrzNvOW0K0pZfRJL+CHB32kHoJFJ_csg@mail.gmail.com>
In-Reply-To: <019d01cf3a1f$4ebfe5f0$ec3fb1d0$@lsst.org>

On Fri, Mar 7, 2014 at 8:07 AM, Paul Lotz <plotz@lsst.org> wrote:

Show 5 quoted lines

> David,
>
> I investigated further and found that \"$LOCAL\" \"$REMOTE\" return the remote and local files (reversed).  (One can easily see this in my 2/28 e-mail.)  Reversing these (\"$REMOTE\" \"$LOCAL\") does indeed reverse the output.  It is easy to work around this issue, but how can this be?
>
> Paul

It's probably working as intended.

The $LOCAL and $REMOTE names come from "git mergetool", where they have better defined semantics.

In the context of a diff, where we're really comparing "A" and "B" they have a little less meaning, but the behavior is well-defined.

When you modify a file locally, the default behavior for "git diff" is to compare your working tree against the index.

The diff will show the changes that will permute the index's copy into the the worktree's copy. In a sense, your modifications are the "remote" thing that is being compared against.

That's why you see a temporary file for $LOCAL ("A") and your worktree's file for $REMOTE (B).

If compare two other things, e.g. "git difftool HEAD~3 HEAD~" then $LOCAL is HEAD~3 and $REMOTE is HEAD~, and they'll all be temporary files.

One analogy is that the $LOCAL thing is the starting point and the $REMOTE thing is what was modified (by the merge) if you think of it from the merging perspective.

Specific tools (e.g. lvcompare) may need the arguments to be specified in a specific order for them to make sense, so it's perfectly acceptable for specific tools to require that $LOCAL and $REMOTE are swapped.

BTW.. we went through a lot of back-and-forth getting the difftool setup correct for lvcompare. In the Git source tree there's a mergetools/ directory where all of the built-in diff/merge tools are defined. Do you think you might be able to contribute a scriptlet for lvcompare so that it is natively supported? That'll save future poor souls from needing to rediscover the correct recipe for getting lvcompare working with difftool. Just a thought.

cheers,

-- 
David