Re: [PATCH] setup_revisions(): turn on diffs for all-negative diff filter

> Argh, I forgot to add Johannes to the cc. Fortunately since then I had a
> moment to look at this, and the solution is pretty simple. So here it is
> as a patch with a test.
>
> -- >8 --
> Subject: setup_revisions(): turn on diffs for all-negative diff filter
>
> When the user gives us a diff filter like --diff-filter=D, we need to do
> a tree diff even if we're not planning to show the diff result itself,
> in order to decide whether to show the commit at all. So there's an
> explicit check of revs->diffopt.filter in setup_revisions(), and we set
> revs->diff if any bits are set.
>
> Originally that "filter" field covered both positive capital-letter
> filters (like "D") and also negative lowercase filters (like "d"), so it
> was sufficient for both cases. But later, 75408ca949 (diff-filter: be
> more careful when looking for negative bits, 2022-01-28) split the
> negative bits out into a "filter_not" field.