Re: [PATCH] diff-files: treat "i-t-a" files as "not-in-index"

Srinidhi Kaushik [off-list ref] writes:

The `diff-files' command and related commands which call `cmd_diff_files()',
consider the "intent-to-add" files as a part of the index when comparing the
work-tree against it. This was previously addressed in [1] and [2] by turning
the option `--ita-invisible-in-index' (introduced in [3]) on by default.

For `diff-files' (and `add -p' as a consequence) to show the i-t-a files as
as new, `ita_invisible_in_index' will be enabled by default here as well.

[1] 0231ae71d3 (diff: turn --ita-invisible-in-index on by default, 2018-05-26)
[2] 425a28e0a4 (diff-lib: allow ita entries treated as "not yet exist in
                index", 2016-10-24)
[3] b42b451919 (diff: add --ita-[in]visible-in-index, 2016-10-24)

Is there any place where we still run the internal diff machinery to
compare the index and the working tree without setting the
ita_invisible_in_index bit on with this patch applied, and if so,
why?  Does the justification why that other place needs to leave
the bit off apply to this codepath as well?

What I am trying to get at is if this is helping only one usecase
for "diff-files" while breaking other usecases.

On the other hand, if there is no longer anybody who wants
ita_invisible_in_index off, perhaps we can get rid of the bit and
lose many conditionals.