Subject: Re: [PATCH v5 1/1] diff.c: When appropriate, use utf8_strwidth()

From: Junio C Hamano <[email-masked]>
Date: Fri, 21 Oct 2022 14:59:09 -0700

Torsten Bögershausen <[email-masked]> writes:

> For the moment I don't have any spare time to spend on Git.
> All your comments are noted, and I hope to get time to address them later.
> If you kick out the branch from seen and the whats cooking list,
> that would be fine with me.

I'd rather not waste the efforts so far.  I am tempted to queue the
following on top or squash it in.

----- >8 --------- >8 --------- >8 --------- >8 --------- >8 -----
Subject: [PATCH] diff: leave NEEDWORK notes in show_stats() function

The previous step made an attempt to correctly compute display
columns allocated and padded different parts of diffstat output.
There are at least two known codepaths in the function that still
mixes up display widths and byte length that need to be fixed.

Signed-off-by: Junio C Hamano <[email-masked]>
---
 diff.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/diff.c b/diff.c
index 2751cae131..1d222d87b2 100644
--- a/diff.c
+++ b/diff.c
@@ -2675,6 +2675,11 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 	 * 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);
 	else
@@ -2750,6 +2755,16 @@ static void show_stats(struct diffstat_t *data, struct diff_options *options)
 			char *slash;
 			prefix = "...";
 			len -= 3;
+			/*
+			 * NEEDSWORK: (name_len - len) counts the display
+			 * width, which would be shorter than the byte
+			 * length of the corresponding substring.
+			 * Advancing "name" by that number of bytes does
+			 * *NOT* skip over that many columns, so it is
+			 * very likely that chomping the pathname at the
+			 * slash we will find starting from "name" will
+			 * leave the resulting string still too long.
+			 */
 			name += name_len - len;
 			slash = strchr(name, '/');
 			if (slash)
-- 
2.38.1-320-g901e6a2134