Merge branch 'jc/conflict-hint' into cc/interpret-trailers-more

* jc/conflict-hint:
  merge & sequencer: turn "Conflicts:" hint into a comment
  builtin/commit.c: extract ignore_non_trailer() helper function
  merge & sequencer: unify codepaths that write "Conflicts:" hint
  builtin/merge.c: drop a parameter that is never used
  git-tag.txt: Add a missing hyphen to `-s`

6 files changed, 110 insertions, 65 deletions

diff --git a/Documentation/git-tag.txt b/Documentation/git-tag.txt
index 320908369f..e953ba4439 100644
--- a/Documentation/git-tag.txt
+++ b/Documentation/git-tag.txt
@@ -42,7 +42,7 @@ committer identity for the current user is used to find the
 GnuPG key for signing. 	The configuration variable `gpg.program`
 is used to specify custom GnuPG binary.
 
-Tag objects (created with `-a`, `s`, or `-u`) are called "annotated"
+Tag objects (created with `-a`, `-s`, or `-u`) are called "annotated"
 tags; they contain a creation date, the tagger name and e-mail, a
 tagging message, and an optional GnuPG signature. Whereas a
 "lightweight" tag is simply a name for an object (usually a commit
diff --git a/builtin/commit.c b/builtin/commit.c
index 41f481bd03..80a618fe13 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c
@@ -669,6 +669,52 @@ static void adjust_comment_line_char(const struct strbuf *sb)
 	comment_line_char = *p;
 }
 
+/*
+ * Inspect sb and determine the true "end" of the log message, in
+ * order to find where to put a new Signed-off-by: line.  Ignored are
+ * trailing comment lines and blank lines, and also the traditional
+ * "Conflicts:" block that is not commented out, so that we can use
+ * "git commit -s --amend" on an existing commit that forgot to remove
+ * it.
+ *
+ * Returns the number of bytes from the tail to ignore, to be fed as
+ * the second parameter to append_signoff().
+ */
+static int ignore_non_trailer(struct strbuf *sb)
+{
+	int boc = 0;
+	int bol = 0;
+	int in_old_conflicts_block = 0;
+
+	while (bol < sb->len) {
+		char *next_line;
+
+		if (!(next_line = memchr(sb->buf + bol, '\n', sb->len - bol)))
+			next_line = sb->buf + sb->len;
+		else
+			next_line++;
+
+		if (sb->buf[bol] == comment_line_char || sb->buf[bol] == '\n') {
+			/* is this the first of the run of comments? */
+			if (!boc)
+				boc = bol;
+			/* otherwise, it is just continuing */
+		} else if (starts_with(sb->buf + bol, "Conflicts:\n")) {
+			in_old_conflicts_block = 1;
+			if (!boc)
+				boc = bol;
+		} else if (in_old_conflicts_block && sb->buf[bol] == '\t') {
+			; /* a pathname in the conflicts block */
+		} else if (boc) {
+			/* the previous was not trailing comment */
+			boc = 0;
+			in_old_conflicts_block = 0;
+		}
+		bol = next_line - sb->buf;
+	}
+	return boc ? sb->len - boc : 0;
+}
+
 static int prepare_to_commit(const char *index_file, const char *prefix,
 			     struct commit *current_head,
 			     struct wt_status *s,
@@ -792,32 +838,8 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 	if (clean_message_contents)
 		stripspace(&sb, 0);
 
-	if (signoff) {
-		/*
-		 * See if we have a Conflicts: block at the end. If yes, count
-		 * its size, so we can ignore it.
-		 */
-		int ignore_footer = 0;
-		int i, eol, previous = 0;
-		const char *nl;
-
-		for (i = 0; i < sb.len; i++) {
-			nl = memchr(sb.buf + i, '\n', sb.len - i);
-			if (nl)
-				eol = nl - sb.buf;
-			else
-				eol = sb.len;
-			if (starts_with(sb.buf + previous, "\nConflicts:\n")) {
-				ignore_footer = sb.len - previous;
-				break;
-			}
-			while (i < eol)
-				i++;
-			previous = eol;
-		}
-
-		append_signoff(&sb, ignore_footer, 0);
-	}
+	if (signoff)
+		append_signoff(&sb, ignore_non_trailer(&sb), 0);
 
 	if (fwrite(sb.buf, 1, sb.len, s->fp) < sb.len)
 		die_errno(_("could not write commit template"));
diff --git a/builtin/merge.c b/builtin/merge.c
index 9da9e30d9b..5370412e00 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -28,6 +28,7 @@
 #include "remote.h"
 #include "fmt-merge-msg.h"
 #include "gpg-interface.h"
+#include "sequencer.h"
 
 #define DEFAULT_TWOHEAD (1<<0)
 #define DEFAULT_OCTOPUS (1<<1)
@@ -880,28 +881,19 @@ static int finish_automerge(struct commit *head,
 	return 0;
 }
 
-static int suggest_conflicts(int renormalizing)
+static int suggest_conflicts(void)
 {
 	const char *filename;
 	FILE *fp;
-	int pos;
+	struct strbuf msgbuf = STRBUF_INIT;
 
 	filename = git_path("MERGE_MSG");
 	fp = fopen(filename, "a");
 	if (!fp)
 		die_errno(_("Could not open '%s' for writing"), filename);
-	fprintf(fp, "\nConflicts:\n");
-	for (pos = 0; pos < active_nr; pos++) {
-		const struct cache_entry *ce = active_cache[pos];
-
-		if (ce_stage(ce)) {
-			fprintf(fp, "\t%s\n", ce->name);
-			while (pos + 1 < active_nr &&
-					!strcmp(ce->name,
-						active_cache[pos + 1]->name))
-				pos++;
-		}
-	}
+
+	append_conflicts_hint(&msgbuf);
+	fputs(msgbuf.buf, fp);
 	fclose(fp);
 	rerere(allow_rerere_auto);
 	printf(_("Automatic merge failed; "
@@ -1550,7 +1542,7 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 		fprintf(stderr, _("Automatic merge went well; "
 			"stopped before committing as requested\n"));
 	else
-		ret = suggest_conflicts(option_renormalize);
+		ret = suggest_conflicts();
 
 done:
 	free(branch_to_free);
diff --git a/sequencer.c b/sequencer.c
index 5e8a207474..f00fd7ce03 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -266,6 +266,23 @@ static int fast_forward_to(const unsigned char *to, const unsigned char *from,
 	return 0;
 }
 
+void append_conflicts_hint(struct strbuf *msgbuf)
+{
+	int i;
+
+	strbuf_addch(msgbuf, '\n');
+	strbuf_commented_addf(msgbuf, "Conflicts:\n");
+	for (i = 0; i < active_nr;) {
+		const struct cache_entry *ce = active_cache[i++];
+		if (ce_stage(ce)) {
+			strbuf_commented_addf(msgbuf, "\t%s\n", ce->name);
+			while (i < active_nr && !strcmp(ce->name,
+							active_cache[i]->name))
+				i++;
+		}
+	}
+}
+
 static int do_recursive_merge(struct commit *base, struct commit *next,
 			      const char *base_label, const char *next_label,
 			      unsigned char *head, struct strbuf *msgbuf,
@@ -306,21 +323,8 @@ static int do_recursive_merge(struct commit *base, struct commit *next,
 	if (opts->signoff)
 		append_signoff(msgbuf, 0, 0);
 
-	if (!clean) {
-		int i;
-		strbuf_addstr(msgbuf, "\nConflicts:\n");
-		for (i = 0; i < active_nr;) {
-			const struct cache_entry *ce = active_cache[i++];
-			if (ce_stage(ce)) {
-				strbuf_addch(msgbuf, '\t');
-				strbuf_addstr(msgbuf, ce->name);
-				strbuf_addch(msgbuf, '\n');
-				while (i < active_nr && !strcmp(ce->name,
-						active_cache[i]->name))
-					i++;
-			}
-		}
-	}
+	if (!clean)
+		append_conflicts_hint(msgbuf);
 
 	return !clean;
 }
diff --git a/sequencer.h b/sequencer.h
index db43e9cf86..5ed5cb1d97 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -53,5 +53,6 @@ int sequencer_pick_revisions(struct replay_opts *opts);
 extern const char sign_off_header[];
 
 void append_signoff(struct strbuf *msgbuf, int ignore_footer, unsigned flag);
+void append_conflicts_hint(struct strbuf *msgbuf);
 
 #endif
diff --git a/t/t3507-cherry-pick-conflict.sh b/t/t3507-cherry-pick-conflict.sh
index 223b98433c..7c5ad08626 100755
--- a/t/t3507-cherry-pick-conflict.sh
+++ b/t/t3507-cherry-pick-conflict.sh
@@ -351,19 +351,45 @@ test_expect_success 'commit after failed cherry-pick does not add duplicated -s'
 test_expect_success 'commit after failed cherry-pick adds -s at the right place' '
 	pristine_detach initial &&
 	test_must_fail git cherry-pick picked &&
+
 	git commit -a -s &&
-	pwd &&
-	cat <<EOF > expected &&
-picked
 
-Signed-off-by: C O Mitter <committer@example.com>
+	# Do S-o-b and Conflicts appear in the right order?
+	cat <<-\EOF >expect &&
+	Signed-off-by: C O Mitter <committer@example.com>
+	# Conflicts:
+	EOF
+	grep -e "^# Conflicts:" -e '^Signed-off-by' <.git/COMMIT_EDITMSG >actual &&
+	test_cmp expect actual &&
+
+	cat <<-\EOF >expected &&
+	picked
 
-Conflicts:
-	foo
-EOF
+	Signed-off-by: C O Mitter <committer@example.com>
+	EOF
 
-	git show -s --pretty=format:%B > actual &&
+	git show -s --pretty=format:%B >actual &&
 	test_cmp expected actual
 '
 
+test_expect_success 'commit --amend -s places the sign-off at the right place' '
+	pristine_detach initial &&
+	test_must_fail git cherry-pick picked &&
+
+	# emulate old-style conflicts block
+	mv .git/MERGE_MSG .git/MERGE_MSG+ &&
+	sed -e "/^# Conflicts:/,\$s/^# *//" <.git/MERGE_MSG+ >.git/MERGE_MSG &&
+
+	git commit -a &&
+	git commit --amend -s &&
+
+	# Do S-o-b and Conflicts appear in the right order?
+	cat <<-\EOF >expect &&
+	Signed-off-by: C O Mitter <committer@example.com>
+	Conflicts:
+	EOF
+	grep -e "^Conflicts:" -e '^Signed-off-by' <.git/COMMIT_EDITMSG >actual &&
+	test_cmp expect actual
+'
+
 test_done