Re: generating combined diff without an existing merge commit

[Jacob Keller <jacob.keller@gmail.com>]

On Fri, Oct 21, 2016 at 2:40 PM, Jacob Keller <jacob.keller@gmail.com> wrote:
> Hi,
>
> I recently determined that I can produce an interdiff for a series
> that handles rebasing nicely and shows the conflicts resolved when
> rebasing plus any other changes.
>
> The basic idea is something like the following, assuming that v1 is a
> tag that points to the first version, v2 is a tag that points to the
> rebased new version, and base is a tag that points to the new base of
> the series (ie: the upstream if the v2 is on a branch and has been
> fully rebased)
>
> git checkout v1
> git merge base
> #perform any further edits to get everything looking like v2
> git commit
> git show -cc HEAD
>
> This is also equivalent to the following without having to actually do
> the merge manually:
>
> git commit-tree v2^{head} -p v1 -p master -m "some merge message"
> git show <output from the commit tree above)
>
> this nicely shows us the combined diff format which correctly shows
> any conflicts required to fix up during the rebase (which we already
> did because we have v2) and it also shows any *other* changes caused
> by v2 but without showing changes which we didn't actually make. (I
> think?)
>
> The result is that we can nicely see what was required to produce v2
> from v1 but without being cluttered by what changed in base.
>
> However, I have to actually generate the commit to do this. I am
> wondering if it is possible today to actually just do something like:
>
> git diff <treeish> <treeish> <treeish> and get the result that I want?
>
> I've already started digging to see if I can do that but haven't found
> anything yet.
>
> Thanks,
> Jake

Turns out that somehow I must have messed up my command because "git
diff <treeish> <treeish> <treeish>" does indeed do exactly what I
want.

Thanks,
Jake