Re: [PATCH 2/7] merge-ort: add ability to record conflict messages in a file

[Elijah Newren <newren@gmail.com>]

On Wed, Sep 29, 2021 at 9:14 AM Junio C Hamano <gitster@pobox.com> wrote:
>
> Elijah Newren <newren@gmail.com> writes:
>
> > I also don't like how diff.orderFile provides a global ordering of the
> > files listed, rather than providing some scheme for relative
> > orderings.  That'd either force me to precompute the diff to determine
> > all the files that were different so I can list _all_ of them,...
>
> Don't we determine all the files that would be listed in the diff
> anyway?  The diffcore pipeline collects all the different filepairs,
> matches them up for rename/copy detection, and finally do the output
> formatting for each individual filepair.

merge-ort is missing one side of the diff.  It only has the parents of
the merge commit, and their merge base.  So, merge-ort would now need
to know about an additional commit (the original merge), and compute
the diff between that and the merge-result it is creating, in advance
of an external caller (log) calling diff to compute the result between
those two trees.

> > So, I'm not so sure about this solution; it feels like it introduces
> > bigger holes than the ugly space character it is fixing.
> >
> >>  - there can be other non-diff data between the individual segments. For
> >>    example, "patch" will skip over non-diff lines. And certainly in Git
> >>    we have our own custom headers. I'm wondering if we could attach
> >>    these annotations to the diff-pair somehow, and then show something
> >>    like:
> >>
> >>      diff --git a/foo.c b/foo.c
> >>      index 1234abcd..5678cdef 100644
> >>      conflict modify/delete foo.c
> >
> > A couple things here...
> >
> > First, I'm not so sure I like the abbreviation here.  Just knowing
> > "modify/delete" might be enough in some cases, but I'd rather have the
> > full messages that would have been printed to the console...
> >
> > Second, what about when there are multiple ...
> >
> > Third, what about the cases where there is no diff, ...
>
> None of the above seems like a problem to me at least from the
> presentation and consumption sides.  There is no rule that extended
> diff headers has to fit on a 72-char line, cannot use line folding
> by inserting LF-SP in the middle of a logical line, and there
> already is at least one case we give an extended diff header without
> a single line of content change (namely, "chmod +x README").

Cool, that's good to hear.  I'll look into it.