commit -v: strip diffs and submodule shortlogs from the commit messagejl/commit-v-strip-marker

When using the '-v' option of "git commit" the diff added to the commit
message temporarily for editing is stripped off after the user exited the
editor by searching for "\ndiff --git " and truncating the commmit message
there if it is found.

But this approach has two problems:

- when the commit message itself contains a line starting with
  "diff --git" it will be truncated there prematurely; and

- when the "diff.submodule" setting is set to "log", the diff may
  start with "Submodule <hash1>..<hash2>", which will be left in
  the commit message while it shouldn't.

Fix that by introducing a special scissor separator line starting with the
comment character ('#' or the core.commentChar config if set) followed by
two lines describing what it is for. The scissor line - which will not be
translated - is used to reliably detect the start of the diff so it can be
chopped off from the commit message, no matter what the user enters there.

Turn a known test failure fixed by this change into a successful test;
also add one for a diff starting with a submodule log and another one for
proper handling of the comment char.

Reported-by: Ari Pollak <ari@debian.org>
Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 27 insertions, 2 deletions

diff --git a/wt-status.c b/wt-status.c
index b4e44baa29..85390b813f 100644
--- a/wt-status.c
+++ b/wt-status.c
@@ -16,6 +16,9 @@
 #include "column.h"
 #include "strbuf.h"
 
+static char cut_line[] =
+"------------------------ >8 ------------------------\n";
+
 static char default_wt_status_colors[][COLOR_MAXLEN] = {
 	GIT_COLOR_NORMAL, /* WT_STATUS_HEADER */
 	GIT_COLOR_GREEN,  /* WT_STATUS_UPDATED */
@@ -767,6 +770,18 @@ conclude:
 	status_printf_ln(s, GIT_COLOR_NORMAL, "");
 }
 
+void wt_status_truncate_message_at_cut_line(struct strbuf *buf)
+{
+	const char *p;
+	struct strbuf pattern = STRBUF_INIT;
+
+	strbuf_addf(&pattern, "%c %s", comment_line_char, cut_line);
+	p = strstr(buf->buf, pattern.buf);
+	if (p && (p == buf->buf || p[-1] == '\n'))
+		strbuf_setlen(buf, p - buf->buf);
+	strbuf_release(&pattern);
+}
+
 static void wt_status_print_verbose(struct wt_status *s)
 {
 	struct rev_info rev;
@@ -787,10 +802,20 @@ static void wt_status_print_verbose(struct wt_status *s)
 	 * If we're not going to stdout, then we definitely don't
 	 * want color, since we are going to the commit message
 	 * file (and even the "auto" setting won't work, since it
-	 * will have checked isatty on stdout).
+	 * will have checked isatty on stdout). But we then do want
+	 * to insert the scissor line here to reliably remove the
+	 * diff before committing.
 	 */
-	if (s->fp != stdout)
+	if (s->fp != stdout) {
+		const char *explanation = _("Do not touch the line above.\nEverything below will be removed.");
+		struct strbuf buf = STRBUF_INIT;
+
 		rev.diffopt.use_color = 0;
+		fprintf(s->fp, "%c %s", comment_line_char, cut_line);
+		strbuf_add_commented_lines(&buf, explanation, strlen(explanation));
+		fputs(buf.buf, s->fp);
+		strbuf_release(&buf);
+	}
 	run_diff_index(&rev, 1);
 }