Re: git-diff bug?

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

Eli Barzilay <eli@barzilay.org> writes:

>> This matches your results.  That the order makes a difference is a bit
>> odd.  Both are valid diffs of the inputs and neither one changes blank
>> lines, though, so it doesn't look like a bug.
>
> How is it valid?

Just this part.  Any patch output that correctly explains how the
preimage text changed to the postimage text is a "valid" diff, and
that is how René used the word.  There are multiple "valid" diff
to bring the preimage to the postimage:

    (preimage)          (postimage)
    aaa                 aaa
    bbb                 bbb
    ccc
                        ccc

In an extreme case, this diff is even valid.

    @@ -1,4 +1,4 @@
    -aaa
    -bbb
    -ccc
    -
    +aaa
    +bbb
    +
    +ccc

It's just that it is not as _useful_ as other valid diff that
explains how the preimage changed to the postimage.

HTH.