Patchdiff

> Heya,
> 
> Do we have anything that allows me to compare two versions of a patch?
> In theory it'd do something like "apply both patches to the their
> merge base, then show the diff between the results". I don't think we
> have something like that, since there's probably some major caveats
> about conflicts when applying the patches to their merge-base. Or
> perhaps my theory is silly, and there's an easier way to compare two
> patches (other than looking at a diff's diff, which I've never been
> good at).

>> Do we have anything that allows me to compare two versions of a patch?
>> In theory it'd do something like "apply both patches to the their
>> merge base, then show the diff between the results". I don't think we
>> have something like that, since there's probably some major caveats
>> about conflicts when applying the patches to their merge-base. Or
>> perhaps my theory is silly, and there's an easier way to compare two
>> patches (other than looking at a diff's diff, which I've never been
>> good at).
>
> What about Git's diff -c/--cc ?  You'd have to reverse the parenthood 
> logic though.

> When showing a merge, there is one end result (the merged version), so it
> fits the model that is a natural extension of two-way diff.  In the "two
> patches walked in a bar, modified the same version and produced two
> different results" case, the common thing is the preimage, not postimage.
> I couldn't come up with a combined output format that visually makes sense
> for that mode of operation.

> Nicolas Pitre <nico@fluxnic.net> writes:
>
>>> Do we have anything that allows me to compare two versions of a patch?
>>> In theory it'd do something like "apply both patches to the their
>>> merge base, then show the diff between the results". I don't think we
>>> have something like that, since there's probably some major caveats
>>> about conflicts when applying the patches to their merge-base. Or
>>> perhaps my theory is silly, and there's an easier way to compare two
>>> patches (other than looking at a diff's diff, which I've never been
>>> good at).
>>
>> What about Git's diff -c/--cc ?  You'd have to reverse the parenthood
>> logic though.
>
> When I did "diff --cc" originally, I thought about its interaction with
> reverse (-R), and gave up.