add-interactive: respect color.diff for diff coloring

The old perl git-add--interactive.perl script used the color.diff config
option to decide whether to color diffs (and if not set, it fell back to
the value of color.ui via git-config's --get-colorbool option). When we
switched to the builtin version, this was lost: we respect only
color.ui. So for example:

  git -c color.diff=false add -p

would color the diff, even when it should not.

The culprit is this line in add-interactive.c's parse_diff():

  if (want_color_fd(1, -1))

That "-1" means "no config has been set", which causes it to fall back
to the color.ui setting. We should instead be passing the value of
color.diff. But the problem is that we never even parse that config
option!

Instead the builtin interactive code parses only the value of
color.interactive, which is used for prompts and other messages. One
could perhaps argue that this should cover interactive diff coloring,
too, but historically it did not. The perl script treated
color.interactive and color.diff separately. So we should grab the
values for both, keeping separate fields in our add_i_state variable,
rather than a single use_color field.

We also load individual color slots (e.g., color.interactive.prompt),
leaving them as the empty string when color is disabled. This happens
via the init_color() helper in add-interactive, which checks that
use_color field. Now that there are two such fields, we need to pass the
appropriate one for each color.

The colors are mostly easy to divide up; color.interactive.* follows
color.interactive, and color.diff.* follows color.diff. But the "reset"
color is tricky. It is used for both types of coloring, but the two can
be configured independently. So we introduce two separate reset colors,
and use each in the appropriate spot.

There are two new tests. The first enables interactive prompt colors but
disables color.diff. We should see a colored prompt but not a colored
diff, showing that we are now respecting color.diff (and not
color.interactive or color.ui).

The second does the opposite. We disable color.interactive but turn on
color.diff with a custom fragment color. When we split a hunk, the
interactive code has to re-color the hunk header, which lets us check
that we correctly loaded the color.diff.frag config based on color.diff,
not color.interactive.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

0 files changed, 0 insertions, 0 deletions