[GSoC PATCH 1/2] diff: handle ANSI chars in prefix when calculating diffstat width

From

LorenzoPegorari <lorenzo.pegorari2002@gmail.com>

Date

Feb 24, 2026, 01:11 UTC

Message-ID

<a798eda511c23ce15df1280a73861ac951459315.1771894207.git.lorenzo.pegorari2002@gmail.com>

In-Reply-To

<cover.1771894207.git.lorenzo.pegorari2002@gmail.com>

Signed-off-by: LorenzoPegorari <lorenzo.pegorari2002@gmail.com>
---
 diff.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/diff.c b/diff.c
index 35b903a9a0..de1db28714 100644
--- a/diff.c
+++ b/diff.c
@@ -2749,7 +2749,9 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 	count = i; /* where we can stop scanning in data->files[] */
 
 	/*
-	 * We have width = stat_width or term_columns() columns total.
+	 * We have width = stat_width or term_columns() columns total
+	 * minus the length of line_prefix skipping ANSI chars to get the
+	 * display width (e.g., to skip ANSI-colored strings in "log --graph").
 	 * We want a maximum of min(max_len, stat_name_width) for the name part.
 	 * We want a maximum of min(max_change, stat_graph_width) for the +- part.
 	 * We also need 1 for " " and 4 + decimal_width(max_change)
@@ -2776,14 +2778,8 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 	 * separators and this message, this message will "overflow"
 	 * making the line longer than the maximum width.
 	 */
-
-	/*
-	 * NEEDSWORK: line_prefix is often used for "log --graph" output
-	 * and contains ANSI-colored string.  utf8_strnwidth() should be
-	 * used to correctly count the display width instead of strlen().
-	 */
 	if (options->stat_width == -1)
-		width = term_columns() - strlen(line_prefix);
+		width = term_columns() - utf8_strnwidth(line_prefix, strlen(line_prefix), 1);
 	else
 		width = options->stat_width ? options->stat_width : 80;
 	number_width = decimal_width(max_change) > number_width ?

-- 
2.43.0