RFC patch, 2 partstrailer: fix to ignore any line starting with '#'

t/t7513-interpret-trailers.sh, trailer.c

diff --git a/t/t7513-interpret-trailers.sh b/t/t7513-interpret-trailers.sh
index 9aae721..aa63b1b 100755
--- a/t/t7513-interpret-trailers.sh
+++ b/t/t7513-interpret-trailers.sh
@@ -150,6 +150,32 @@ test_expect_success 'with 2 files arguments' '
 	test_cmp expected actual
 '
 
+test_expect_success 'with message that has comments' '
+	cat basic_message >>message_with_comments &&
+	sed -e "s/ Z\$/ /" >>message_with_comments <<-\EOF &&
+		# comment
+
+		# other comment
+		Cc: Z
+		# yet another comment
+		Reviewed-by: Johan
+		Reviewed-by: Z
+		# last comment
+
+	EOF
+	cat basic_patch >>message_with_comments &&
+	cat basic_message >expected &&
+	cat >>expected <<-\EOF &&
+		# comment
+
+		Cc: Peff
+		Reviewed-by: Johan
+	EOF
+	cat basic_patch >>expected &&
+	git interpret-trailers --trim-empty --trailer "Cc: Peff" message_with_comments >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'with commit complex message and trailer args' '
 	cat complex_message_body >expected &&
 	sed -e "s/ Z\$/ /" >>expected <<-\EOF &&
diff --git a/trailer.c b/trailer.c
index 4d32b42..81b2c5c 100644
--- a/trailer.c
+++ b/trailer.c
@@ -644,10 +644,9 @@ static int find_patch_start(struct strbuf **lines, int count)
 /*
  * Return the (0 based) index of the first trailer line or count if
  * there are no trailers. Trailers are searched only in the lines from
- * index (count - 1) down to index 0. The has_blank_line parameter
- * tells if there is a blank line before the trailers.
+ * index (count - 1) down to index 0.
  */
-static int find_trailer_start(struct strbuf **lines, int count, int *has_blank_line)
+static int find_trailer_start(struct strbuf **lines, int count)
 {
 	int start, only_spaces = 1;
 
@@ -656,10 +655,11 @@ static int find_trailer_start(struct strbuf **lines, int count, int *has_blank_l
 	 * for a line with only spaces before lines with one ':'.
 	 */
 	for (start = count - 1; start >= 0; start--) {
+		if (lines[start]->buf[0] == '#')
+			continue;
 		if (contains_only_spaces(lines[start]->buf)) {
 			if (only_spaces)
 				continue;
-			*has_blank_line = 1;
 			return start + 1;
 		}
 		if (strchr(lines[start]->buf, ':')) {
@@ -667,13 +667,20 @@ static int find_trailer_start(struct strbuf **lines, int count, int *has_blank_l
 				only_spaces = 0;
 			continue;
 		}
-		*has_blank_line = start == count - 1 ?
-		  0 : contains_only_spaces(lines[start + 1]->buf);
 		return count;
 	}
 
-	*has_blank_line = only_spaces ? count > 0 : 0;
-	return only_spaces ? count : start + 1;
+	return only_spaces ? count : 0;
+}
+
+static int has_blank_line_before(struct strbuf **lines, int start)
+{
+	for (;start >= 0; start--) {
+		if (lines[start]->buf[0] == '#')
+			continue;
+		return contains_only_spaces(lines[start]->buf);
+	}
+	return 0;
 }
 
 static void print_lines(struct strbuf **lines, int start, int end)
@@ -688,19 +695,19 @@ static int process_input_file(struct strbuf **lines,
 			      struct trailer_item **in_tok_last)
 {
 	int count = 0;
-	int patch_start, trailer_start, has_blank_line, i;
+	int patch_start, trailer_start, i;
 
 	/* Get the line count */
 	while (lines[count])
 		count++;
 
 	patch_start = find_patch_start(lines, count);
-	trailer_start = find_trailer_start(lines, patch_start, &has_blank_line);
+	trailer_start = find_trailer_start(lines, patch_start);
 
 	/* Print lines before the trailers as is */
 	print_lines(lines, 0, trailer_start);
 
-	if (!has_blank_line)
+	if (!has_blank_line_before(lines, trailer_start - 1))
 		printf("\n");
 
 	/* Parse trailer lines */

diff --git a/Documentation/git-interpret-trailers.txt b/Documentation/git-interpret-trailers.txt
index 450ec54..42c2f71 100644
--- a/Documentation/git-interpret-trailers.txt
+++ b/Documentation/git-interpret-trailers.txt
@@ -134,9 +134,105 @@ If the command contains the `$ARG` string, this string will be
 replaced with the <value> part of an existing trailer with the same
 <token>, if any, before the command is launched.
 
+EXAMPLES
+--------
+
+* Configure a 'sign' trailer with a 'Signed-off-by: ' key, and then
+  add two of these trailers to a message:
++
+------------
+$ git config trailer.sign.key "Signed-off-by: "
+$ cat msg.txt
+subject
+
+message
+$ cat msg.txt | git interpret-trailers --trailer 'sign: Alice <alice@example.com>' --trailer 'sign: Bob <bob@example.com>'
+subject
+
+message
+
+Signed-off-by: Alice <alice@example.com>
+Signed-off-by: Bob <bob@example.com>
+------------
+
+* Extract the last commit as a patch, and add a 'Cc' and a
+  'Reviewed-by' trailer to it:
++
+------------
+$ git format-patch -1
+0001-foo.patch
+$ git interpret-trailers --trailer 'Cc: Alice <alice@example.com>' --trailer 'Reviewed-by: Bob <bob@example.com>' 0001-foo.patch >0001-bar.patch
+------------
+
+* Configure a 'sign' trailer with a command to automatically add a
+  'Signed-off-by: ' with the author information only if there is no
+  'Signed-off-by: ' already, and show how it works:
++
+------------
+$ git config trailer.sign.key "Signed-off-by: "
+$ git config trailer.sign.ifmissing add
+$ git config trailer.sign.ifexists doNothing
+$ git config trailer.sign.command 'echo "$(git config user.name) <$(git config user.email)>"'
+$ git interpret-trailers <<EOF
+> EOF
+
+Signed-off-by: Bob <bob@example.com>
+$ git interpret-trailers <<EOF
+> Signed-off-by: Alice <alice@example.com>
+> EOF
+
+Signed-off-by: Alice <alice@example.com>
+------------
+
+* Configure a 'fix' trailer with a command to show the subject of a
+  commit that is fixed, and show how it works:
++
+------------
+$ git config trailer.fix.key "Fixes #"
+$ git config trailer.fix.ifExists "overwrite"
+$ git config trailer.fix.command "git log -1 --oneline --format=\"%h (%s)\" --abbrev-commit --abbrev=14 \$ARG"
+$ git interpret-trailers <<EOF
+> subject
+> 
+> message
+> 
+> fix: HEAD~2
+> EOF
+subject
+
+message
+
+Fixes #fe3187489d69c4 (subject of fixed commit)
+------------
+
+* Configure a commit template with some trailers with empty values,
+  then configure a commit-msg hook that uses git interpret-trailers to
+  remove trailers with empty values and to add a 'git-version'
+  trailer:
++
+------------
+$ cat >commit_template.txt <<EOF
+> ***subject***
+> 
+> ***message***
+> 
+> Fixes: 
+> Cc: 
+> Reviewed-by: 
+> Signed-off-by: 
+> EOF
+$ git config commit.template commit_template.txt
+$ cat >.git/hooks/commit-msg <<EOF
+#!/bin/sh
+git interpret-trailers --trim-empty --trailer "git-version: \$(git describe)" "\$1" > "\$1.new"
+mv "\$1.new" "\$1"
+EOF
+$ chmod +x .git/hooks/commit-msg
+------------
+
 SEE ALSO
 --------
-linkgit:git-commit[1]
+linkgit:git-commit[1], linkgit:git-format-patch[1], linkgit:git-config[1]
 
 GIT
 ---