Subject: [PATCH 06/13] diff: pass o->use_color directly to fill_metainfo()

From: Jeff King <[email-masked]>
Date: Tue, 16 Sep 2025 16:20:26 -0400

We pass the use_color parameter of fill_metainfo() as a strict boolean,
using:

  want_color(o->use_color) && !pgm

to derive its value. But then inside the function, we pass it to
diff_get_color(), which expects one of the git_colorbool enum values,
and so feeds it to want_color() again.

Even though want_color() produces a strict 0/1 boolean, this doesn't
produce wrong results because want_color() is idempotent. Since
GIT_COLOR_ALWAYS and NEVER are defined as 1 and 0, and because
want_color() passes through those values, evaluating "want_color(foo)"
and "want_color(want_color(foo))" will return the same result.

But as part of a longer strategy to align the types we use for storing
these values, let's pass through the colorbool directly. To handle the
"&&" case here, we'll convert the presence of "pgm" into "NEVER", which
arguably makes the intent of the code more clear anyway.

Signed-off-by: Jeff King <[email-masked]>
---
 diff.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/diff.c b/diff.c
index cc3542e7f4..6b12596642 100644
--- a/diff.c
+++ b/diff.c
@@ -4596,7 +4596,7 @@ static void run_diff_cmd(const struct external_diff *pgm,
 		 */
 		fill_metainfo(msg, name, other, one, two, o, p,
 			      &must_show_header,
-			      want_color(o->use_color) && !pgm);
+			      pgm ? GIT_COLOR_NEVER : o->use_color);
 		xfrm_msg = msg->len ? msg->buf : NULL;
 	}
 
-- 
2.51.0.527.g34bc42dacd