Re: [PATCH 02/14] format-patch: add --interdiff option to embed diff in cover letter

> Add an --interdiff option to automate this process. The argument to
> --interdiff specifies the tip of the previous attempt against which to
> generate the interdiff.
>
> Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
> ---
> diff --git a/interdiff.c b/interdiff.c
> @@ -0,0 +1,17 @@
> +void show_interdiff(struct rev_info *rev)
> +{
> +       struct diff_options opts;
> +
> +       memcpy(&opts, &rev->diffopt, sizeof(opts));
> +       opts.output_format = DIFF_FORMAT_PATCH;
> +       diff_setup_done(&opts);
> +
> +       diff_tree_oid(rev->idiff_oid1, rev->idiff_oid2, "", &opts);