Re: [RFD] Combine diff improvements

[Junio C Hamano <gitster@pobox.com>]

Antoine Pelisse <apelisse@gmail.com> writes:

> While if we invert the two parents order we will have:
> - 3
> --1
> --2
> - 4
>  -3
>  -4
>
> While clearly, in both cases, the optimal solution would be close to:
> - 3
> --1
> --2
>  -3
> --4

We should shoot for better readability as the primary goal.  When I
am viewing "--cc" output, I find it easier to read if the lines for
the same parent are consecutive.  That is, I find the right one far
easier to grok than the left one:

     - 1                - 1
      -2                - 3
     - 3                 -2
      -4                 -4

when trying to see what got changed from the first parent (we had 1
and then 3 and whatever comes after this block; 2 and 4 are noise
and it makes it easier to skip them because they are together).

This can probably be done as a post-process phase after you find the
coalescing matches to express the result in the smallest number of
lines, but I thought it is worth mentioning that not all solutions
with the same number of lines are equally good.