diff: handle ANSI escape codes in prefix when calculating diffstat width

The diffstat width is calculated by taking the terminal width and incorrectly subtracting the `strlen()` of `line_prefix`, instead of the actual display width of `line_prefix`, which may contain ANSI escape codes (e.g., ANSI-colored strings in `log --graph --stat`). Utilize the display width instead, obtained via `utf8_strnwidth()` with the flag `skip_ansi`. Signed-off-by: LorenzoPegorari <lorenzo.pegorari2002@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>

LorenzoPegorari committed Feb 27, 2026 at 22:45 UTC 1a9df8de368cbebd881336f64e424422f3dbb993
1 file changed +4 -8
diff.c
+4 -8
@@ -2713,7 +2713,9 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
2713 count = i; /* where we can stop scanning in data->files[] */
2714
2715 /*
2716 - * We have width = stat_width or term_columns() columns total.
2716 + * We have width = stat_width or term_columns() columns total minus the
2717 + * length of line_prefix skipping ANSI escape codes to get the display
2718 + * width (e.g., skip ANSI-colored strings in "log --graph --stat").
2719 * We want a maximum of min(max_len, stat_name_width) for the name part.
2720 * We want a maximum of min(max_change, stat_graph_width) for the +- part.
2721 * We also need 1 for " " and 4 + decimal_width(max_change)
@@ -2740,14 +2742,8 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
2742 * separators and this message, this message will "overflow"
2743 * making the line longer than the maximum width.
2744 */
2743 -
2744 - /*
2745 - * NEEDSWORK: line_prefix is often used for "log --graph" output
2746 - * and contains ANSI-colored string. utf8_strnwidth() should be
2747 - * used to correctly count the display width instead of strlen().
2748 - */
2745 if (options->stat_width == -1)
2750 - width = term_columns() - strlen(line_prefix);
2746 + width = term_columns() - utf8_strnwidth(line_prefix, strlen(line_prefix), 1);
2747 else
2748 width = options->stat_width ? options->stat_width : 80;
2749 number_width = decimal_width(max_change) > number_width ?