Re: [PATCH 3/4] diff-lib: refactor functions

> Unlike the original, this always makes two needless structure
> assignments for anything that is not a submodule.
>
> Can we fix that regression before moving forward?
>
> Even when ce_mode is a gitlink, if .ignore_submodules bit is set,
> the two structure assignments between diffopt->flags and orig_flags
> become necessary, so the original was already doing extra copies but
> we do not have to make it worse.

> Strange indentation.  It is unclear why this bottom 1/3 of the loop
> body of run_diff_files() need to be a separate helper function,
> while the top 2/3 does not.  The resulting loop (below) becomes very
> hard to follow because the reader cannot tell when diff_change() is
> called and when it is not.
>
> Overall, I see this change detrimental to diff-lib API at this step
> in the series.  Later steps may show something more rewarding than
> the downsides we see here, hopefully.