patch, 21 partst4205: add test for trailer in log with nonstandard separator

diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 757575d3f6..42544fb07a 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -757,6 +757,18 @@ test_expect_success 'pretty format %(trailers) combining separator/key/valueonly
 	test_cmp expect actual
 '
 
+test_expect_success 'pretty format %(trailers) with nonstandard separator' '
+	git commit --allow-empty -F - <<-\EOF &&
+	Some fix
+
+	Closes #1234
+	EOF
+
+	git -c "trailer.separators=:#" log --no-walk --pretty="format:%s% (trailers:key=Closes)"  >actual &&
+	echo "Some fix Closes: 1234" >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'trailer parsing not fooled by --- line' '
 	git commit --allow-empty -F - <<-\EOF &&
 	this is the subject

diff --git a/Documentation/git-interpret-trailers.txt b/Documentation/git-interpret-trailers.txt
index 96ec6499f0..a4be8aed66 100644
--- a/Documentation/git-interpret-trailers.txt
+++ b/Documentation/git-interpret-trailers.txt
@@ -25,6 +25,11 @@ Otherwise, this command applies the arguments passed using the
 `--trailer` option, if any, to the commit message part of each input
 file. The result is emitted on the standard output.
 
+When trailers read from input they will be changed into "canonical"
+form if the trailer has a corresponding 'trailer.<token>.key'
+configuration value. This means that it will use the exact spelling
+(upper case vs lower case and separator) defined in configuration.
+
 Some configuration variables control the way the `--trailer` arguments
 are applied to each commit message and the way any existing trailer in
 the commit message is changed. They also make it possible to

diff --git a/trailer.c b/trailer.c
index 02061877b4..0db3bba3b1 100644
--- a/trailer.c
+++ b/trailer.c
@@ -656,8 +656,7 @@ static ssize_t find_separator(const char *line, const char *separators)
  * If separator_pos is -1, interpret the whole trailer as a token.
  */
 static void parse_trailer(struct strbuf *tok, struct strbuf *val, struct strbuf *sep,
-			 const struct conf_info **conf, const char *trailer,
-			 ssize_t separator_pos)
+			 const char *trailer, ssize_t separator_pos)
 {
 	if (separator_pos != -1) {
 		size_t sep_spacing_begin = separator_pos;
@@ -677,9 +676,6 @@ static void parse_trailer(struct strbuf *tok, struct strbuf *val, struct strbuf
 		strbuf_addstr(tok, trailer);
 		strbuf_trim(tok);
 	}
-
-	if (conf)
-		*conf = lookup_conf_for_tok (tok);
 }
 
 static struct trailer_item *add_trailer_item(struct list_head *head, char *tok,
@@ -752,8 +748,9 @@ static void process_command_line_args(struct list_head *arg_head,
 			      (int) sb.len, sb.buf);
 			strbuf_release(&sb);
 		} else {
-			parse_trailer(&tok, &val, NULL, &conf, tr->text,
+			parse_trailer(&tok, &val, NULL, tr->text,
 				      separator_pos);
+			conf = lookup_conf_for_tok(&tok);
 			add_arg_item(arg_head,
 				     strbuf_detach(&tok, NULL),
 				     strbuf_detach(&val, NULL),
@@ -1026,8 +1023,9 @@ static size_t process_input_file(FILE *outfile,
 		separator_pos = find_separator(trailer, separators);
 		if (separator_pos >= 1) {
 			const struct conf_info *conf;
-			parse_trailer(&tok, &val, &sep, &conf, trailer,
+			parse_trailer(&tok, &val, &sep, trailer,
 				      separator_pos);
+			conf = lookup_conf_for_tok(&tok);
 			if (opts->unfold)
 				unfold_value(&val);
 			add_trailer_item(head,
@@ -1221,7 +1219,8 @@ static void format_trailer_info(struct strbuf *out,
 
 			const struct conf_info *conf;
 
-			parse_trailer(&tok, &val, NULL, &conf, trailer, separator_pos);
+			parse_trailer(&tok, &val, NULL, trailer, separator_pos);
+			conf = lookup_conf_for_tok(&tok);
 			if (!opts->filter ||
 			    opts->filter(&tok, conf ? conf->name : NULL, opts->filter_data)) {
 				if (opts->unfold)
@@ -1282,7 +1281,7 @@ int trailer_iterator_advance(struct trailer_iterator *iter)
 
 		strbuf_reset(&iter->key);
 		strbuf_reset(&iter->val);
-		parse_trailer(&iter->key, &iter->val, NULL, NULL,
+		parse_trailer(&iter->key, &iter->val, NULL,
 			      trailer, separator_pos);
 		unfold_value(&iter->val);
 		return 1;

diff --git a/t/t7513-interpret-trailers.sh b/t/t7513-interpret-trailers.sh
index 6ddc2f5573..a99d6d7e3b 100755
--- a/t/t7513-interpret-trailers.sh
+++ b/t/t7513-interpret-trailers.sh
@@ -151,6 +151,41 @@ test_expect_success 'spelling and separators are not canonicalized with --parse
 	test_cmp expected actual
 '
 
+# Matching currently is prefix matching, causing "This-trailer" to be normalized too
+test_expect_failure 'config option matches exact only' '
+	cat >patch <<-\EOF &&
+
+		This-trailer: a
+		 b
+		This-trailer-exact: b
+		 c
+		This-trailer-exact-plus-some: c
+		 d
+	EOF
+	cat >expected <<-\EOF &&
+		This-trailer: a b
+		THIS-TRAILER-EXACT: b c
+		This-trailer-exact-plus-some: c d
+	EOF
+	git -c "trailer.tte.key=THIS-TRAILER-EXACT" interpret-trailers --only-input --only-trailers --unfold patch >actual &&
+	test_cmp expected actual
+'
+
+# Matching currently uses the config key even if key value is different
+test_expect_failure 'config option matches exact only' '
+	cat >patch <<-\EOF &&
+
+		Ticket: 1234
+		Reference-ticket: 99
+	EOF
+	cat >expected <<-\EOF &&
+		Ticket: 1234
+		Reference-Ticket: 99
+	EOF
+	git -c "trailer.ticket.key=Reference-Ticket" interpret-trailers --only-input --only-trailers patch >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'with only a title in the message' '
 	cat >expected <<-\EOF &&
 		area: change

Documentation/git-interpret-trailers.txt, builtin/interpret-trailers.c, t/t7513-interpret-trailers.sh, trailer.c, trailer.h

diff --git a/Documentation/git-interpret-trailers.txt b/Documentation/git-interpret-trailers.txt
index a4be8aed66..a9e6816525 100644
--- a/Documentation/git-interpret-trailers.txt
+++ b/Documentation/git-interpret-trailers.txt
@@ -129,13 +129,16 @@ OPTIONS
 
 --parse::
 	A convenience alias for `--only-trailers --only-input
-	--unfold`.
+	--unfold --no-canonicalize`.
 
 --no-divider::
 	Do not treat `---` as the end of the commit message. Use this
 	when you know your input contains just the commit message itself
 	(and not an email or the output of `git format-patch`).
 
+--no-canonicalize::
+	Disable canonicalization of input trailers.
+
 CONFIGURATION VARIABLES
 -----------------------
 
diff --git a/builtin/interpret-trailers.c b/builtin/interpret-trailers.c
index 84748eafc0..51678657a3 100644
--- a/builtin/interpret-trailers.c
+++ b/builtin/interpret-trailers.c
@@ -81,6 +81,7 @@ static int parse_opt_parse(const struct option *opt, const char *arg,
 	v->only_trailers = 1;
 	v->only_input = 1;
 	v->unfold = 1;
+	v->canonicalize = 0;
 	BUG_ON_OPT_NEG(unset);
 	BUG_ON_OPT_ARG(arg);
 	return 0;
@@ -105,6 +106,7 @@ int cmd_interpret_trailers(int argc, const char **argv, const char *prefix)
 		OPT_BOOL(0, "only-trailers", &opts.only_trailers, N_("output only the trailers")),
 		OPT_BOOL(0, "only-input", &opts.only_input, N_("do not apply config rules")),
 		OPT_BOOL(0, "unfold", &opts.unfold, N_("join whitespace-continued values")),
+		OPT_BOOL(0, "canonicalize", &opts.canonicalize, N_("canonicalize spelling for trailers with config")),
 		OPT_CALLBACK_F(0, "parse", &opts, NULL, N_("set parsing options"),
 			PARSE_OPT_NOARG | PARSE_OPT_NONEG, parse_opt_parse),
 		OPT_BOOL(0, "no-divider", &opts.no_divider, N_("do not treat --- specially")),
@@ -112,6 +114,7 @@ int cmd_interpret_trailers(int argc, const char **argv, const char *prefix)
 				N_("trailer(s) to add"), option_parse_trailer),
 		OPT_END()
 	};
+	opts.canonicalize = 1;
 
 	git_config(git_default_config, NULL);
 
diff --git a/t/t7513-interpret-trailers.sh b/t/t7513-interpret-trailers.sh
index 6602790b5f..4b3a2484b5 100755
--- a/t/t7513-interpret-trailers.sh
+++ b/t/t7513-interpret-trailers.sh
@@ -99,6 +99,58 @@ test_expect_success 'with config option on the command line' '
 	test_cmp expected actual
 '
 
+test_expect_success 'spelling and separators are canonicalized from configs with key' '
+	cat >patch <<-\EOF &&
+		non-trailer-line
+
+		ReviEweD-bY :abc
+		ReviEwEd-bY) rst
+		ReviEweD-BY ; xyz
+		aCked-bY) only separator gets normalized
+	EOF
+	cat >expected <<-\EOF &&
+		Reviewed-By: abc
+		Reviewed-By: rst
+		Reviewed-By: xyz
+		aCked-bY: only separator gets normalized
+	EOF
+	git \
+		-c "trailer.separators=:);" \
+		-c "trailer.rb.key=Reviewed-By" \
+		-c "trailer.Acked-By.ifmissing=doNothing" \
+		interpret-trailers --only-trailers --only-input patch >actual &&
+	test_cmp expected actual
+'
+
+test_expect_success 'spelling and separators are not canonicalized with --parse or --no-canonicalize' '
+	cat >patch <<-\EOF &&
+		non-trailer-line
+
+		ReviEweD-bY :abc
+		ReviEwEd-bY) rst
+		ReviEweD-BY ; xyz
+		aCked-bY) not normalized
+	EOF
+	cat >expected <<-\EOF &&
+		ReviEweD-bY :abc
+		ReviEwEd-bY) rst
+		ReviEweD-BY ; xyz
+		aCked-bY) not normalized
+	EOF
+	git \
+		-c "trailer.separators=:);" \
+		-c "trailer.rb.key=Reviewed-By" \
+		-c "trailer.Acked-By.ifmissing=doNothing" \
+		interpret-trailers --parse patch >actual &&
+	test_cmp expected actual &&
+	git \
+		-c "trailer.separators=:);" \
+		-c "trailer.rb.key=Reviewed-By" \
+		-c "trailer.Acked-By.ifmissing=doNothing" \
+		interpret-trailers --only-trailers --only-input --no-canonicalize patch >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'with only a title in the message' '
 	cat >expected <<-\EOF &&
 		area: change
diff --git a/trailer.c b/trailer.c
index 102eca0127..110d3ed226 100644
--- a/trailer.c
+++ b/trailer.c
@@ -141,14 +141,18 @@ static void free_arg_item(struct arg_item *item)
 	free(item);
 }
 
-static void print_item(FILE *outfile, const struct trailer_item *item)
+static void print_item(FILE *outfile, const struct trailer_item *item,
+		       const struct process_trailer_options *opts)
 {
 	if (item->token) {
 		const char *tok = item->token;
 		const char *sep = (char []){separators[0], ' ', '\0'};
 		const struct conf_info *conf = item->conf;
 
-		if (conf) {
+		if (!opts->canonicalize && item->used_separator)
+			sep = item->used_separator;
+
+		if (opts->canonicalize && conf) {
 			if (conf->key)
 				tok = conf->key;
 			if (conf->nondefault_separator)
@@ -170,7 +174,7 @@ static void print_all(FILE *outfile, struct list_head *head,
 		item = list_entry(pos, struct trailer_item, list);
 		if ((!opts->trim_empty || strlen(item->value) > 0) &&
 		    (!opts->only_trailers || item->token))
-			print_item(outfile, item);
+			print_item(outfile, item, opts);
 	}
 }
 
diff --git a/trailer.h b/trailer.h
index b362b0d44d..aad856da8c 100644
--- a/trailer.h
+++ b/trailer.h
@@ -72,6 +72,7 @@ struct process_trailer_options {
 	int unfold;
 	int no_divider;
 	int value_only;
+	int canonicalize;
 	const struct strbuf *separator;
 	int (*filter)(const struct strbuf *, const char *alias, void *);
 	void *filter_data;

diff --git a/trailer.c b/trailer.c
index 227df1c0ef..047781463a 100644
--- a/trailer.c
+++ b/trailer.c
@@ -177,13 +177,11 @@ static void print_all(FILE *outfile, struct list_head *head,
 	}
 }
 
-static struct trailer_item *trailer_from_arg(struct arg_item *arg_tok)
+static struct trailer_item *trailer_from_arg(const struct arg_item *arg_tok)
 {
 	struct trailer_item *new_item = xcalloc(sizeof(*new_item), 1);
-	new_item->token = arg_tok->token;
-	new_item->value = arg_tok->value;
-	arg_tok->token = arg_tok->value = NULL;
-	free_arg_item(arg_tok);
+	new_item->token = xstrdup(arg_tok->token);
+	new_item->value = xstrdup(arg_tok->value);
 	return new_item;
 }
 
@@ -274,7 +272,6 @@ static void apply_arg_if_exists(struct trailer_item *in_tok,
 {
 	switch (arg_tok->conf.if_exists) {
 	case EXISTS_DO_NOTHING:
-		free_arg_item(arg_tok);
 		break;
 	case EXISTS_REPLACE:
 		apply_item_command(in_tok, arg_tok);
@@ -290,15 +287,11 @@ static void apply_arg_if_exists(struct trailer_item *in_tok,
 		apply_item_command(in_tok, arg_tok);
 		if (check_if_different(in_tok, arg_tok, 1, head))
 			add_arg_to_input_list(on_tok, arg_tok);
-		else
-			free_arg_item(arg_tok);
 		break;
 	case EXISTS_ADD_IF_DIFFERENT_NEIGHBOR:
 		apply_item_command(in_tok, arg_tok);
 		if (check_if_different(on_tok, arg_tok, 0, head))
 			add_arg_to_input_list(on_tok, arg_tok);
-		else
-			free_arg_item(arg_tok);
 		break;
 	default:
 		BUG("trailer.c: unhandled value %d",
@@ -314,7 +307,6 @@ static void apply_arg_if_missing(struct list_head *head,
 
 	switch (arg_tok->conf.if_missing) {
 	case MISSING_DO_NOTHING:
-		free_arg_item(arg_tok);
 		break;
 	case MISSING_ADD:
 		where = arg_tok->conf.where;
@@ -364,15 +356,13 @@ static int find_same_and_apply_arg(struct list_head *head,
 static void process_trailers_lists(struct list_head *head,
 				   struct list_head *arg_head)
 {
-	struct list_head *pos, *p;
+	struct list_head *pos;
 	struct arg_item *arg_tok;
 
-	list_for_each_safe(pos, p, arg_head) {
+	list_for_each(pos, arg_head) {
 		int applied = 0;
 		arg_tok = list_entry(pos, struct arg_item, list);
 
-		list_del(pos);
-
 		applied = find_same_and_apply_arg(head, arg_tok);
 
 		if (!applied)
@@ -999,6 +989,15 @@ static void free_all_trailer_items(struct list_head *head)
 	}
 }
 
+static void free_all_arg_items(struct list_head *head)
+{
+	struct list_head *pos, *p;
+	list_for_each_safe(pos, p, head) {
+		list_del(pos);
+		free_arg_item(list_entry(pos, struct arg_item, list));
+	}
+}
+
 static struct tempfile *trailers_tempfile;
 
 static FILE *create_in_place_tempfile(const char *file)
@@ -1035,6 +1034,7 @@ void process_trailers(const char *file,
 		      struct list_head *new_trailer_head)
 {
 	LIST_HEAD(head);
+	LIST_HEAD(arg_head);
 	struct strbuf sb = STRBUF_INIT;
 	size_t trailer_end;
 	FILE *outfile = stdout;
@@ -1050,7 +1050,6 @@ void process_trailers(const char *file,
 	trailer_end = process_input_file(outfile, sb.buf, &head, opts);
 
 	if (!opts->only_input) {
-		LIST_HEAD(arg_head);
 		process_command_line_args(&arg_head, new_trailer_head);
 		process_trailers_lists(&head, &arg_head);
 	}
@@ -1058,6 +1057,7 @@ void process_trailers(const char *file,
 	print_all(outfile, &head, opts);
 
 	free_all_trailer_items(&head);
+	free_all_arg_items(&arg_head);
 
 	/* Print the lines after the trailers as is */
 	if (!opts->only_trailers)

diff --git a/trailer.c b/trailer.c
index 110d3ed226..937cf1edeb 100644
--- a/trailer.c
+++ b/trailer.c
@@ -829,7 +829,6 @@ static size_t find_trailer_start(const char *buf, size_t len)
 {
 	const char *s;
 	ssize_t end_of_title, l;
-	int only_spaces = 1;
 	int recognized_prefix = 0, trailer_lines = 0, non_trailer_lines = 0;
 	/*
 	 * Number of possible continuation lines encountered. This will be
@@ -856,6 +855,12 @@ static size_t find_trailer_start(const char *buf, size_t len)
 	 * consists of at least 25% trailers.
 	 */
 	for (l = last_line(buf, len);
+	     l >= end_of_title;
+	     l = last_line(buf, l)) {
+		if (!is_blank_line(buf + l) && buf[l] != comment_line_char)
+			break;
+	}
+	for (;
 	     l >= end_of_title;
 	     l = last_line(buf, l)) {
 		const char *bol = buf + l;
@@ -868,8 +873,6 @@ static size_t find_trailer_start(const char *buf, size_t len)
 			continue;
 		}
 		if (is_blank_line(bol)) {
-			if (only_spaces)
-				continue;
 			non_trailer_lines += possible_continuation_lines;
 			if (recognized_prefix &&
 			    trailer_lines * 3 >= non_trailer_lines)
@@ -878,7 +881,6 @@ static size_t find_trailer_start(const char *buf, size_t len)
 				return next_line(bol) - buf;
 			return len;
 		}
-		only_spaces = 0;
 
 		for (p = git_generated_prefixes; *p; p++) {
 			if (starts_with(bol, *p)) {

Documentation/pretty-formats.txt, pretty.c, t/t4205-log-pretty-formats.sh, trailer.c, trailer.h

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index 84bbc7439a..1714fa447d 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -256,7 +256,9 @@ endif::git-rev-list[]
 ** 'key=<K>': only show trailers with specified key. Matching is done
    case-insensitively and trailing colon is optional. If option is
    given multiple times trailer lines matching any of the keys are
-   shown. This option automatically enables the `only` option so that
+   shown. If `trailer.<token>.key` configuration option is set 'token'
+   can be used as an alias for showing trailers with the value in
+   key. This option automatically enables the `only` option so that
    non-trailer lines in the trailer block are hidden. If that is not
    desired it can be disabled with `only=false`.  E.g.,
    `%(trailers:key=Reviewed-by)` shows trailer lines with key
diff --git a/pretty.c b/pretty.c
index 7a7708a0ea..3c374abffe 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1135,7 +1135,7 @@ static int match_placeholder_bool_arg(const char *to_parse, const char *candidat
 	return 1;
 }
 
-static int format_trailer_match_cb(const struct strbuf *key, void *ud)
+static int format_trailer_match_cb(const struct strbuf *key, const char *alias, void *ud)
 {
 	const struct string_list *list = ud;
 	const struct string_list_item *item;
@@ -1144,6 +1144,9 @@ static int format_trailer_match_cb(const struct strbuf *key, void *ud)
 		if (key->len == (uintptr_t)item->util &&
 		    !strncasecmp(item->string, key->buf, key->len))
 			return 1;
+		if (alias && strlen(alias) == (uintptr_t)item->util &&
+		    !strncasecmp(item->string, alias, (uintptr_t)item->util))
+			return 1;
 	}
 	return 0;
 }
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 204c149d5a..757575d3f6 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -676,6 +676,12 @@ test_expect_success 'pretty format %(trailers:key=foo) multiple keys' '
 	test_cmp expect actual
 '
 
+test_expect_success 'pretty format %(trailers:key=foo) alias in config' '
+	git -c trailer.ab.key=Acked-by log --no-walk --pretty="format:%(trailers:key=ab)" >actual &&
+	echo "Acked-by: A U Thor <author@example.com>" >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success '%(trailers:key=nonexistent) becomes empty' '
 	git log --no-walk --pretty="x%(trailers:key=Nacked-by)x" >actual &&
 	echo "xx" >expect &&
diff --git a/trailer.c b/trailer.c
index ca7a823af6..8c0687a529 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1148,8 +1148,11 @@ static void format_trailer_info(struct strbuf *out,
 			struct strbuf tok = STRBUF_INIT;
 			struct strbuf val = STRBUF_INIT;
 
-			parse_trailer(&tok, &val, NULL, trailer, separator_pos);
-			if (!opts->filter || opts->filter(&tok, opts->filter_data)) {
+			const struct conf_info *conf;
+
+			parse_trailer(&tok, &val, &conf, trailer, separator_pos);
+			if (!opts->filter ||
+			    opts->filter(&tok, conf ? conf->name : NULL, opts->filter_data)) {
 				if (opts->unfold)
 					unfold_value(&val);
 
diff --git a/trailer.h b/trailer.h
index cd93e7ddea..b362b0d44d 100644
--- a/trailer.h
+++ b/trailer.h
@@ -73,7 +73,7 @@ struct process_trailer_options {
 	int no_divider;
 	int value_only;
 	const struct strbuf *separator;
-	int (*filter)(const struct strbuf *, void *);
+	int (*filter)(const struct strbuf *, const char *alias, void *);
 	void *filter_data;
 };
 

diff --git a/trailer.c b/trailer.c
index 0986d4267e..71921e70ce 100644
--- a/trailer.c
+++ b/trailer.c
@@ -147,22 +147,22 @@ static char last_non_space_char(const char *s)
 	return '\0';
 }
 
-static void print_tok_val(FILE *outfile, const char *tok, const char *val)
+static void print_item(FILE *outfile, const struct trailer_item *item)
 {
 	char c;
 
-	if (!tok) {
-		fprintf(outfile, "%s\n", val);
+	if (!item->token) {
+		fprintf(outfile, "%s\n", item->value);
 		return;
 	}
 
-	c = last_non_space_char(tok);
+	c = last_non_space_char(item->token);
 	if (!c)
 		return;
 	if (strchr(separators, c))
-		fprintf(outfile, "%s%s\n", tok, val);
+		fprintf(outfile, "%s%s\n", item->token, item->value);
 	else
-		fprintf(outfile, "%s%c %s\n", tok, separators[0], val);
+		fprintf(outfile, "%s%c %s\n", item->token, separators[0], item->value);
 }
 
 static void print_all(FILE *outfile, struct list_head *head,
@@ -174,7 +174,7 @@ static void print_all(FILE *outfile, struct list_head *head,
 		item = list_entry(pos, struct trailer_item, list);
 		if ((!opts->trim_empty || strlen(item->value) > 0) &&
 		    (!opts->only_trailers || item->token))
-			print_tok_val(outfile, item->token, item->value);
+			print_item(outfile, item);
 	}
 }
 

diff --git a/trailer.c b/trailer.c
index 71921e70ce..d6882155be 100644
--- a/trailer.c
+++ b/trailer.c
@@ -149,20 +149,24 @@ static char last_non_space_char(const char *s)
 
 static void print_item(FILE *outfile, const struct trailer_item *item)
 {
-	char c;
-
-	if (!item->token) {
-		fprintf(outfile, "%s\n", item->value);
-		return;
+	if (item->token) {
+		const char *tok = item->token;
+		const struct conf_info *conf = item->conf;
+		char c;
+
+		if (conf && conf->key)
+			tok = conf->key;
+
+		c = last_non_space_char(tok);
+		if (!c)
+			return;
+		if (strchr(separators, c))
+			fputs(tok, outfile);
+		else
+			fprintf(outfile, "%s%c ", tok, separators[0]);
 	}
 
-	c = last_non_space_char(item->token);
-	if (!c)
-		return;
-	if (strchr(separators, c))
-		fprintf(outfile, "%s%s\n", item->token, item->value);
-	else
-		fprintf(outfile, "%s%c %s\n", item->token, separators[0], item->value);
+	fprintf(outfile, "%s\n", item->value);
 }
 
 static void print_all(FILE *outfile, struct list_head *head,
@@ -569,15 +573,6 @@ static void ensure_configured(void)
 	configured = 1;
 }
 
-static const char *token_from_conf(const struct conf_info *conf, char *tok)
-{
-	if (conf->key)
-		return conf->key;
-	if (tok)
-		return tok;
-	return conf->name;
-}
-
 static int token_matches_conf(const char *tok, const struct conf_info *conf, size_t tok_len)
 {
 	if (!strncasecmp(tok, conf->name, tok_len))
@@ -646,11 +641,8 @@ static void parse_trailer(struct strbuf *tok, struct strbuf *val,
 	list_for_each(pos, &conf_head) {
 		item = list_entry(pos, struct conf_info_item, list);
 		if (token_matches_conf(tok->buf, &item->conf, tok_len)) {
-			char *tok_buf = strbuf_detach(tok, NULL);
 			if (conf)
 				*conf = &item->conf;
-			strbuf_addstr(tok, token_from_conf(&item->conf, tok_buf));
-			free(tok_buf);
 			break;
 		}
 	}
@@ -706,7 +698,7 @@ static void process_command_line_args(struct list_head *arg_head,
 		item = list_entry(pos, struct conf_info_item, list);
 		if (item->conf.command)
 			add_arg_item(arg_head,
-				     xstrdup(token_from_conf(&item->conf, NULL)),
+				     xstrdup(item->conf.name),
 				     xstrdup(""),
 				     &item->conf, NULL);
 	}

diff --git a/trailer.c b/trailer.c
index 047781463a..0986d4267e 100644
--- a/trailer.c
+++ b/trailer.c
@@ -34,6 +34,7 @@ struct trailer_item {
 	 */
 	char *token;
 	char *value;
+	const struct conf_info *conf;
 };
 
 struct arg_item {
@@ -182,6 +183,7 @@ static struct trailer_item *trailer_from_arg(const struct arg_item *arg_tok)
 	struct trailer_item *new_item = xcalloc(sizeof(*new_item), 1);
 	new_item->token = xstrdup(arg_tok->token);
 	new_item->value = xstrdup(arg_tok->value);
+	new_item->conf = &arg_tok->conf;
 	return new_item;
 }
 
@@ -655,11 +657,12 @@ static void parse_trailer(struct strbuf *tok, struct strbuf *val,
 }
 
 static struct trailer_item *add_trailer_item(struct list_head *head, char *tok,
-					     char *val)
+					     char *val, const struct conf_info *conf)
 {
 	struct trailer_item *new_item = xcalloc(sizeof(*new_item), 1);
 	new_item->token = tok;
 	new_item->value = val;
+	new_item->conf = conf;
 	list_add_tail(&new_item->list, head);
 	return new_item;
 }
@@ -959,19 +962,22 @@ static size_t process_input_file(FILE *outfile,
 			continue;
 		separator_pos = find_separator(trailer, separators);
 		if (separator_pos >= 1) {
-			parse_trailer(&tok, &val, NULL, trailer,
+			const struct conf_info *conf;
+			parse_trailer(&tok, &val, &conf, trailer,
 				      separator_pos);
 			if (opts->unfold)
 				unfold_value(&val);
 			add_trailer_item(head,
 					 strbuf_detach(&tok, NULL),
-					 strbuf_detach(&val, NULL));
+					 strbuf_detach(&val, NULL),
+					 conf);
 		} else if (!opts->only_trailers) {
 			strbuf_addstr(&val, trailer);
 			strbuf_strip_suffix(&val, "\n");
 			add_trailer_item(head,
 					 NULL,
-					 strbuf_detach(&val, NULL));
+					 strbuf_detach(&val, NULL),
+					 NULL);
 		}
 	}
 

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

diff --git a/t/t7513-interpret-trailers.sh b/t/t7513-interpret-trailers.sh
index b1e9a9e6d1..6ddc2f5573 100755
--- a/t/t7513-interpret-trailers.sh
+++ b/t/t7513-interpret-trailers.sh
@@ -239,12 +239,7 @@ test_expect_success 'with non-trailer lines mixed with a configured trailer' '
 	test_cmp expected actual
 '
 
-# This fails because "c:/windows/tmp/stuff/temp.txt" is classified as
-# a trailer line because "c" is a prefix of "Confirmed-By". Therefore
-# the new trailer is appended to that (non-trailer) block rather than
-# creating a new block. It also canonicalize the "trailer" to
-# "Confirmed-By: /windows/tmp/stuff/temp.txt"
-test_expect_failure 'with non-trailer lines mixed with prefix of configured trailer' '
+test_expect_success 'with non-trailer lines mixed with prefix of configured trailer' '
 	cat >patch <<-\EOF &&
 		some subject
 
diff --git a/trailer.c b/trailer.c
index 21877e4c06..d75d240e10 100644
--- a/trailer.c
+++ b/trailer.c
@@ -831,10 +831,20 @@ enum trailer_classification {
 	BLANK,
 };
 
+static int starts_with_separator(const char *buf)
+{
+	while (*buf == ' ' || *buf == '\t')
+		buf++;
+	if (!*buf)
+		return 0;
+	return !!strchr(separators, *buf);
+}
+
 static enum trailer_classification classify_trailer_line(const char *line)
 {
 	const char **p;
 	ssize_t separator_pos;
+	struct list_head *pos;
 
 	if (line[0] == comment_line_char)
 		return COMMENT;
@@ -849,19 +859,17 @@ static enum trailer_classification classify_trailer_line(const char *line)
 		if (starts_with(line, *p))
 			return GIT_GENERATED_PREFIX;
 
-
-	separator_pos = find_separator(line, separators);
-	if (separator_pos >= 1) {
-		struct list_head *pos;
-
-		list_for_each(pos, &conf_head) {
-			struct conf_info_item *item;
-			item = list_entry(pos, struct conf_info_item, list);
-			if (token_matches_conf(line, &item->conf,
-			                       separator_pos))
+	list_for_each(pos, &conf_head) {
+		struct conf_info_item *item = list_entry(pos, struct conf_info_item, list);
+		const char *conftrailer = item->conf.key ? item->conf.key : item->conf.name;
+		if (istarts_with(line, conftrailer)) {
+			if (starts_with_separator (line + strlen (conftrailer)))
 				return CONFIGURED_TRAILER;
 		}
+	}
 
+	separator_pos = find_separator(line, separators);
+	if (separator_pos >= 1) {
 		return TRAILER;
 	}
 

diff --git a/t/t7513-interpret-trailers.sh b/t/t7513-interpret-trailers.sh
index 4b3a2484b5..b1e9a9e6d1 100755
--- a/t/t7513-interpret-trailers.sh
+++ b/t/t7513-interpret-trailers.sh
@@ -239,6 +239,35 @@ test_expect_success 'with non-trailer lines mixed with a configured trailer' '
 	test_cmp expected actual
 '
 
+# This fails because "c:/windows/tmp/stuff/temp.txt" is classified as
+# a trailer line because "c" is a prefix of "Confirmed-By". Therefore
+# the new trailer is appended to that (non-trailer) block rather than
+# creating a new block. It also canonicalize the "trailer" to
+# "Confirmed-By: /windows/tmp/stuff/temp.txt"
+test_expect_failure 'with non-trailer lines mixed with prefix of configured trailer' '
+	cat >patch <<-\EOF &&
+		some subject
+
+		This is clearly not a trailer line. But
+		on next line there is a a windows path
+		c:/windows/tmp/stuff/temp.txt but that
+		should not make this classify as a trailer block
+	EOF
+	cat >expected <<-\EOF &&
+		some subject
+
+		This is clearly not a trailer line. But
+		on next line there is a a windows path
+		c:/windows/tmp/stuff/temp.txt but that
+		should not make this classify as a trailer block
+
+		t: v
+	EOF
+	test_config trailer.confirmedby.key "Confirmed-By" &&
+	git interpret-trailers --trailer "t: v" patch >actual &&
+	test_cmp expected actual
+'
+
 test_expect_success 'with non-trailer lines mixed with a non-configured trailer' '
 	cat >patch <<-\EOF &&
 

diff --git a/trailer.c b/trailer.c
index efb88c2008..ca7a823af6 100644
--- a/trailer.c
+++ b/trailer.c
@@ -19,6 +19,11 @@ struct conf_info {
 	enum trailer_if_missing if_missing;
 };
 
+struct conf_info_item {
+	struct list_head list;
+	struct conf_info conf;
+};
+
 static struct conf_info default_conf_info;
 
 struct trailer_item {
@@ -432,16 +437,16 @@ static void duplicate_conf(struct conf_info *dst, const struct conf_info *src)
 	dst->command = xstrdup_or_null(src->command);
 }
 
-static struct arg_item *get_conf_item(const char *name)
+static struct conf_info *get_conf_item(const char *name)
 {
 	struct list_head *pos;
-	struct arg_item *item;
+	struct conf_info_item *item;
 
 	/* Look up item with same name */
 	list_for_each(pos, &conf_head) {
-		item = list_entry(pos, struct arg_item, list);
+		item = list_entry(pos, struct conf_info_item, list);
 		if (!strcasecmp(item->conf.name, name))
-			return item;
+			return &item->conf;
 	}
 
 	/* Item does not already exists, create it */
@@ -451,7 +456,7 @@ static struct arg_item *get_conf_item(const char *name)
 
 	list_add_tail(&item->list, &conf_head);
 
-	return item;
+	return &item->conf;
 }
 
 enum trailer_info_type { TRAILER_KEY, TRAILER_COMMAND, TRAILER_WHERE,
@@ -502,7 +507,6 @@ static int git_trailer_default_config(const char *conf_key, const char *value, v
 static int git_trailer_config(const char *conf_key, const char *value, void *cb)
 {
 	const char *trailer_item, *variable_name;
-	struct arg_item *item;
 	struct conf_info *conf;
 	char *name = NULL;
 	enum trailer_info_type type;
@@ -527,8 +531,7 @@ static int git_trailer_config(const char *conf_key, const char *value, void *cb)
 	if (!name)
 		return 0;
 
-	item = get_conf_item(name);
-	conf = &item->conf;
+	conf = get_conf_item(name);
 	free(name);
 
 	switch (type) {
@@ -630,7 +633,7 @@ static void parse_trailer(struct strbuf *tok, struct strbuf *val,
 			 const struct conf_info **conf, const char *trailer,
 			 ssize_t separator_pos)
 {
-	struct arg_item *item;
+	struct conf_info_item *item;
 	size_t tok_len;
 	struct list_head *pos;
 
@@ -649,7 +652,7 @@ static void parse_trailer(struct strbuf *tok, struct strbuf *val,
 	if (conf)
 		*conf = &default_conf_info;
 	list_for_each(pos, &conf_head) {
-		item = list_entry(pos, struct arg_item, list);
+		item = list_entry(pos, struct conf_info_item, list);
 		if (token_matches_conf(tok->buf, &item->conf, tok_len)) {
 			char *tok_buf = strbuf_detach(tok, NULL);
 			if (conf)
@@ -693,7 +696,7 @@ static void add_arg_item(struct list_head *arg_head, char *tok, char *val,
 static void process_command_line_args(struct list_head *arg_head,
 				      struct list_head *new_trailer_head)
 {
-	struct arg_item *item;
+	struct conf_info_item *item;
 	struct strbuf tok = STRBUF_INIT;
 	struct strbuf val = STRBUF_INIT;
 	const struct conf_info *conf;
@@ -707,7 +710,7 @@ static void process_command_line_args(struct list_head *arg_head,
 
 	/* Add an arg item for each configured trailer with a command */
 	list_for_each(pos, &conf_head) {
-		item = list_entry(pos, struct arg_item, list);
+		item = list_entry(pos, struct conf_info_item, list);
 		if (item->conf.command)
 			add_arg_item(arg_head,
 				     xstrdup(token_from_conf(&item->conf, NULL)),
@@ -877,8 +880,8 @@ static size_t find_trailer_start(const char *buf, size_t len)
 			if (recognized_prefix)
 				continue;
 			list_for_each(pos, &conf_head) {
-				struct arg_item *item;
-				item = list_entry(pos, struct arg_item, list);
+				struct conf_info_item *item;
+				item = list_entry(pos, struct conf_info_item, list);
 				if (token_matches_conf(bol, &item->conf,
 						       separator_pos)) {
 					recognized_prefix = 1;

diff --git a/trailer.c b/trailer.c
index 1592e6c998..102eca0127 100644
--- a/trailer.c
+++ b/trailer.c
@@ -13,6 +13,7 @@
 struct conf_info {
 	char *name;
 	char *key;
+	char *nondefault_separator;
 	char *command;
 	enum trailer_where where;
 	enum trailer_if_exists if_exists;
@@ -140,32 +141,21 @@ static void free_arg_item(struct arg_item *item)
 	free(item);
 }
 
-static char last_non_space_char(const char *s)
-{
-	int i;
-	for (i = strlen(s) - 1; i >= 0; i--)
-		if (!isspace(s[i]))
-			return s[i];
-	return '\0';
-}
-
 static void print_item(FILE *outfile, const struct trailer_item *item)
 {
 	if (item->token) {
 		const char *tok = item->token;
+		const char *sep = (char []){separators[0], ' ', '\0'};
 		const struct conf_info *conf = item->conf;
-		char c;
 
-		if (conf && conf->key)
-			tok = conf->key;
+		if (conf) {
+			if (conf->key)
+				tok = conf->key;
+			if (conf->nondefault_separator)
+				sep = conf->nondefault_separator;
+		}
 
-		c = last_non_space_char(tok);
-		if (!c)
-			return;
-		if (strchr(separators, c))
-			fputs(tok, outfile);
-		else
-			fprintf(outfile, "%s%c ", tok, separators[0]);
+		fprintf(outfile, "%s%s", tok, sep);
 	}
 
 	fprintf(outfile, "%s\n", item->value);
@@ -502,6 +492,34 @@ static int git_trailer_default_config(const char *conf_key, const char *value, v
 	return 0;
 }
 
+static void git_trailer_config_key(const char *conf_key, const char *value, struct conf_info *conf)
+{
+	const char *end = value + strlen(value) - 1;
+
+	while (end > value && isspace(*end))
+		end--;
+
+	if (end == value) {
+		warning(_("Ignoring empty token for key '%s'"), conf_key);
+		return;
+	}
+
+	if (strchr(separators, *end)) {
+		const char *token_end = end - 1;
+		while (token_end > value && isspace(*token_end))
+			token_end--;
+		if (token_end == value) {
+			warning(_("Ignoring empty token for key '%s'"), conf_key);
+			return;
+		}
+
+		conf->key = xstrndup(value, token_end - value + 1);
+		conf->nondefault_separator = xstrdup(token_end + 1);
+	} else {
+		conf->key = xstrdup(value);
+	}
+}
+
 static int git_trailer_config(const char *conf_key, const char *value, void *cb)
 {
 	const char *trailer_item, *variable_name;
@@ -536,7 +554,8 @@ static int git_trailer_config(const char *conf_key, const char *value, void *cb)
 	case TRAILER_KEY:
 		if (conf->key)
 			warning(_("more than one %s"), conf_key);
-		conf->key = xstrdup(value);
+
+		git_trailer_config_key (conf_key, value, conf);
 		break;
 	case TRAILER_COMMAND:
 		if (conf->command)

diff --git a/trailer.c b/trailer.c
index d6882155be..1592e6c998 100644
--- a/trailer.c
+++ b/trailer.c
@@ -34,6 +34,7 @@ struct trailer_item {
 	 */
 	char *token;
 	char *value;
+	char *used_separator;
 	const struct conf_info *conf;
 };
 
@@ -125,6 +126,7 @@ static void free_trailer_item(struct trailer_item *item)
 {
 	free(item->token);
 	free(item->value);
+	free(item->used_separator);
 	free(item);
 }
 
@@ -616,18 +618,26 @@ static ssize_t find_separator(const char *line, const char *separators)
  *
  * If separator_pos is -1, interpret the whole trailer as a token.
  */
-static void parse_trailer(struct strbuf *tok, struct strbuf *val,
+static void parse_trailer(struct strbuf *tok, struct strbuf *val, struct strbuf *sep,
 			 const struct conf_info **conf, const char *trailer,
 			 ssize_t separator_pos)
 {
 	struct conf_info_item *item;
-	size_t tok_len;
 	struct list_head *pos;
 
 	if (separator_pos != -1) {
-		strbuf_add(tok, trailer, separator_pos);
-		strbuf_trim(tok);
-		strbuf_addstr(val, trailer + separator_pos + 1);
+		size_t sep_spacing_begin = separator_pos;
+		size_t sep_spacing_end = separator_pos + 1;
+
+		while (sep_spacing_begin > 0 && trailer[sep_spacing_begin - 1] == ' ')
+			sep_spacing_begin--;
+		while (trailer[sep_spacing_end] == ' ')
+			sep_spacing_end++;
+
+		strbuf_add(tok, trailer, sep_spacing_begin);
+		if (sep)
+			strbuf_add(sep, trailer + sep_spacing_begin, sep_spacing_end - sep_spacing_begin);
+		strbuf_addstr(val, trailer + sep_spacing_end);
 		strbuf_trim(val);
 	} else {
 		strbuf_addstr(tok, trailer);
@@ -635,12 +645,11 @@ static void parse_trailer(struct strbuf *tok, struct strbuf *val,
 	}
 
 	/* Lookup if the token matches something in the config */
-	tok_len = token_len_without_separator(tok->buf, tok->len);
 	if (conf)
 		*conf = &default_conf_info;
 	list_for_each(pos, &conf_head) {
 		item = list_entry(pos, struct conf_info_item, list);
-		if (token_matches_conf(tok->buf, &item->conf, tok_len)) {
+		if (token_matches_conf(tok->buf, &item->conf, tok->len)) {
 			if (conf)
 				*conf = &item->conf;
 			break;
@@ -649,11 +658,12 @@ static void parse_trailer(struct strbuf *tok, struct strbuf *val,
 }
 
 static struct trailer_item *add_trailer_item(struct list_head *head, char *tok,
-					     char *val, const struct conf_info *conf)
+					     char *val, char *separator, const struct conf_info *conf)
 {
 	struct trailer_item *new_item = xcalloc(sizeof(*new_item), 1);
 	new_item->token = tok;
 	new_item->value = val;
+	new_item->used_separator = separator;
 	new_item->conf = conf;
 	list_add_tail(&new_item->list, head);
 	return new_item;
@@ -717,7 +727,7 @@ static void process_command_line_args(struct list_head *arg_head,
 			      (int) sb.len, sb.buf);
 			strbuf_release(&sb);
 		} else {
-			parse_trailer(&tok, &val, &conf, tr->text,
+			parse_trailer(&tok, &val, NULL, &conf, tr->text,
 				      separator_pos);
 			add_arg_item(arg_head,
 				     strbuf_detach(&tok, NULL),
@@ -936,6 +946,7 @@ static size_t process_input_file(FILE *outfile,
 	struct trailer_info info;
 	struct strbuf tok = STRBUF_INIT;
 	struct strbuf val = STRBUF_INIT;
+	struct strbuf sep = STRBUF_INIT;
 	size_t i;
 
 	trailer_info_get(&info, str, opts);
@@ -955,13 +966,14 @@ static size_t process_input_file(FILE *outfile,
 		separator_pos = find_separator(trailer, separators);
 		if (separator_pos >= 1) {
 			const struct conf_info *conf;
-			parse_trailer(&tok, &val, &conf, trailer,
+			parse_trailer(&tok, &val, &sep, &conf, trailer,
 				      separator_pos);
 			if (opts->unfold)
 				unfold_value(&val);
 			add_trailer_item(head,
 					 strbuf_detach(&tok, NULL),
 					 strbuf_detach(&val, NULL),
+					 strbuf_detach(&sep, NULL),
 					 conf);
 		} else if (!opts->only_trailers) {
 			strbuf_addstr(&val, trailer);
@@ -969,6 +981,7 @@ static size_t process_input_file(FILE *outfile,
 			add_trailer_item(head,
 					 NULL,
 					 strbuf_detach(&val, NULL),
+					 NULL,
 					 NULL);
 		}
 	}
@@ -1148,7 +1161,7 @@ static void format_trailer_info(struct strbuf *out,
 
 			const struct conf_info *conf;
 
-			parse_trailer(&tok, &val, &conf, trailer, separator_pos);
+			parse_trailer(&tok, &val, NULL, &conf, trailer, separator_pos);
 			if (!opts->filter ||
 			    opts->filter(&tok, conf ? conf->name : NULL, opts->filter_data)) {
 				if (opts->unfold)
@@ -1209,7 +1222,7 @@ int trailer_iterator_advance(struct trailer_iterator *iter)
 
 		strbuf_reset(&iter->key);
 		strbuf_reset(&iter->val);
-		parse_trailer(&iter->key, &iter->val, NULL,
+		parse_trailer(&iter->key, &iter->val, NULL, NULL,
 			      trailer, separator_pos);
 		unfold_value(&iter->val);
 		return 1;

diff --git a/trailer.c b/trailer.c
index d75d240e10..02061877b4 100644
--- a/trailer.c
+++ b/trailer.c
@@ -605,6 +605,20 @@ static int token_matches_conf(const char *tok, const struct conf_info *conf, siz
 	return conf->key ? !strncasecmp(tok, conf->key, tok_len) : 0;
 }
 
+static const struct conf_info *lookup_conf_for_tok(const struct strbuf *tok)
+{
+	struct conf_info_item *item;
+	struct list_head *pos;
+
+	list_for_each(pos, &conf_head) {
+		item = list_entry(pos, struct conf_info_item, list);
+		if (token_matches_conf(tok->buf, &item->conf, tok->len)) {
+			return &item->conf;
+		}
+	}
+	return &default_conf_info;
+}
+
 /*
  * If the given line is of the form
  * "<token><optional whitespace><separator>..." or "<separator>...", return the
@@ -645,9 +659,6 @@ static void parse_trailer(struct strbuf *tok, struct strbuf *val, struct strbuf
 			 const struct conf_info **conf, const char *trailer,
 			 ssize_t separator_pos)
 {
-	struct conf_info_item *item;
-	struct list_head *pos;
-
 	if (separator_pos != -1) {
 		size_t sep_spacing_begin = separator_pos;
 		size_t sep_spacing_end = separator_pos + 1;
@@ -667,17 +678,8 @@ static void parse_trailer(struct strbuf *tok, struct strbuf *val, struct strbuf
 		strbuf_trim(tok);
 	}
 
-	/* Lookup if the token matches something in the config */
 	if (conf)
-		*conf = &default_conf_info;
-	list_for_each(pos, &conf_head) {
-		item = list_entry(pos, struct conf_info_item, list);
-		if (token_matches_conf(tok->buf, &item->conf, tok->len)) {
-			if (conf)
-				*conf = &item->conf;
-			break;
-		}
-	}
+		*conf = lookup_conf_for_tok (tok);
 }
 
 static struct trailer_item *add_trailer_item(struct list_head *head, char *tok,

diff --git a/trailer.c b/trailer.c
index 8c0687a529..227df1c0ef 100644
--- a/trailer.c
+++ b/trailer.c
@@ -990,7 +990,7 @@ static size_t process_input_file(FILE *outfile,
 	return info.trailer_end - str;
 }
 
-static void free_all(struct list_head *head)
+static void free_all_trailer_items(struct list_head *head)
 {
 	struct list_head *pos, *p;
 	list_for_each_safe(pos, p, head) {
@@ -1057,7 +1057,7 @@ void process_trailers(const char *file,
 
 	print_all(outfile, &head, opts);
 
-	free_all(&head);
+	free_all_trailer_items(&head);
 
 	/* Print the lines after the trailers as is */
 	if (!opts->only_trailers)

diff --git a/trailer.c b/trailer.c
index 3f7391d793..efb88c2008 100644
--- a/trailer.c
+++ b/trailer.c
@@ -574,20 +574,20 @@ static void ensure_configured(void)
 	configured = 1;
 }
 
-static const char *token_from_item(struct arg_item *item, char *tok)
+static const char *token_from_conf(const struct conf_info *conf, char *tok)
 {
-	if (item->conf.key)
-		return item->conf.key;
+	if (conf->key)
+		return conf->key;
 	if (tok)
 		return tok;
-	return item->conf.name;
+	return conf->name;
 }
 
-static int token_matches_item(const char *tok, struct arg_item *item, size_t tok_len)
+static int token_matches_conf(const char *tok, const struct conf_info *conf, size_t tok_len)
 {
-	if (!strncasecmp(tok, item->conf.name, tok_len))
+	if (!strncasecmp(tok, conf->name, tok_len))
 		return 1;
-	return item->conf.key ? !strncasecmp(tok, item->conf.key, tok_len) : 0;
+	return conf->key ? !strncasecmp(tok, conf->key, tok_len) : 0;
 }
 
 /*
@@ -650,11 +650,11 @@ static void parse_trailer(struct strbuf *tok, struct strbuf *val,
 		*conf = &default_conf_info;
 	list_for_each(pos, &conf_head) {
 		item = list_entry(pos, struct arg_item, list);
-		if (token_matches_item(tok->buf, item, tok_len)) {
+		if (token_matches_conf(tok->buf, &item->conf, tok_len)) {
 			char *tok_buf = strbuf_detach(tok, NULL);
 			if (conf)
 				*conf = &item->conf;
-			strbuf_addstr(tok, token_from_item(item, tok_buf));
+			strbuf_addstr(tok, token_from_conf(&item->conf, tok_buf));
 			free(tok_buf);
 			break;
 		}
@@ -710,7 +710,7 @@ static void process_command_line_args(struct list_head *arg_head,
 		item = list_entry(pos, struct arg_item, list);
 		if (item->conf.command)
 			add_arg_item(arg_head,
-				     xstrdup(token_from_item(item, NULL)),
+				     xstrdup(token_from_conf(&item->conf, NULL)),
 				     xstrdup(""),
 				     &item->conf, NULL);
 	}
@@ -879,7 +879,7 @@ static size_t find_trailer_start(const char *buf, size_t len)
 			list_for_each(pos, &conf_head) {
 				struct arg_item *item;
 				item = list_entry(pos, struct arg_item, list);
-				if (token_matches_item(bol, item,
+				if (token_matches_conf(bol, &item->conf,
 						       separator_pos)) {
 					recognized_prefix = 1;
 					break;

diff --git a/trailer.c b/trailer.c
index 937cf1edeb..21877e4c06 100644
--- a/trailer.c
+++ b/trailer.c
@@ -821,6 +821,53 @@ static size_t find_patch_start(const char *str)
 	return s - str;
 }
 
+enum trailer_classification {
+	GIT_GENERATED_PREFIX,
+	CONFIGURED_TRAILER,
+	TRAILER,
+	CONTINUATION,
+	NON_TRAILER,
+	COMMENT,
+	BLANK,
+};
+
+static enum trailer_classification classify_trailer_line(const char *line)
+{
+	const char **p;
+	ssize_t separator_pos;
+
+	if (line[0] == comment_line_char)
+		return COMMENT;
+
+	if (is_blank_line(line))
+		return BLANK;
+
+	if (isspace(line[0]))
+		return CONTINUATION;
+
+	for (p = git_generated_prefixes; *p; p++)
+		if (starts_with(line, *p))
+			return GIT_GENERATED_PREFIX;
+
+
+	separator_pos = find_separator(line, separators);
+	if (separator_pos >= 1) {
+		struct list_head *pos;
+
+		list_for_each(pos, &conf_head) {
+			struct conf_info_item *item;
+			item = list_entry(pos, struct conf_info_item, list);
+			if (token_matches_conf(line, &item->conf,
+			                       separator_pos))
+				return CONFIGURED_TRAILER;
+		}
+
+		return TRAILER;
+	}
+
+	return NON_TRAILER;
+}
+
 /*
  * Return the position of the first trailer line or len if there are no
  * trailers.
@@ -864,59 +911,37 @@ static size_t find_trailer_start(const char *buf, size_t len)
 	     l >= end_of_title;
 	     l = last_line(buf, l)) {
 		const char *bol = buf + l;
-		const char **p;
-		ssize_t separator_pos;
 
-		if (bol[0] == comment_line_char) {
-			non_trailer_lines += possible_continuation_lines;
-			possible_continuation_lines = 0;
-			continue;
-		}
-		if (is_blank_line(bol)) {
-			non_trailer_lines += possible_continuation_lines;
-			if (recognized_prefix &&
-			    trailer_lines * 3 >= non_trailer_lines)
-				return next_line(bol) - buf;
-			else if (trailer_lines && !non_trailer_lines)
-				return next_line(bol) - buf;
-			return len;
-		}
-
-		for (p = git_generated_prefixes; *p; p++) {
-			if (starts_with(bol, *p)) {
+		switch (classify_trailer_line(bol)) {
+			case GIT_GENERATED_PREFIX:
+			case CONFIGURED_TRAILER:
+				recognized_prefix = 1;
+				/* fallthrough */
+			case TRAILER:
 				trailer_lines++;
 				possible_continuation_lines = 0;
-				recognized_prefix = 1;
-				goto continue_outer_loop;
-			}
-		}
-
-		separator_pos = find_separator(bol, separators);
-		if (separator_pos >= 1 && !isspace(bol[0])) {
-			struct list_head *pos;
-
-			trailer_lines++;
-			possible_continuation_lines = 0;
-			if (recognized_prefix)
-				continue;
-			list_for_each(pos, &conf_head) {
-				struct conf_info_item *item;
-				item = list_entry(pos, struct conf_info_item, list);
-				if (token_matches_conf(bol, &item->conf,
-						       separator_pos)) {
-					recognized_prefix = 1;
-					break;
-				}
-			}
-		} else if (isspace(bol[0]))
-			possible_continuation_lines++;
-		else {
-			non_trailer_lines++;
-			non_trailer_lines += possible_continuation_lines;
-			possible_continuation_lines = 0;
+				break;
+			case CONTINUATION:
+				possible_continuation_lines++;
+				break;
+			case NON_TRAILER:
+				non_trailer_lines++;
+				non_trailer_lines += possible_continuation_lines;
+				possible_continuation_lines = 0;
+				break;
+			case COMMENT:
+				non_trailer_lines += possible_continuation_lines;
+				possible_continuation_lines = 0;
+				break;
+			case BLANK:
+				non_trailer_lines += possible_continuation_lines;
+				if (recognized_prefix &&
+					trailer_lines * 3 >= non_trailer_lines)
+					return next_line(bol) - buf;
+				else if (trailer_lines && !non_trailer_lines)
+					return next_line(bol) - buf;
+				return len;
 		}
-continue_outer_loop:
-		;
 	}
 
 	return len;

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

diff --git a/t/t7513-interpret-trailers.sh b/t/t7513-interpret-trailers.sh
index a99d6d7e3b..9e06fa4454 100755
--- a/t/t7513-interpret-trailers.sh
+++ b/t/t7513-interpret-trailers.sh
@@ -151,8 +151,7 @@ test_expect_success 'spelling and separators are not canonicalized with --parse
 	test_cmp expected actual
 '
 
-# Matching currently is prefix matching, causing "This-trailer" to be normalized too
-test_expect_failure 'config option matches exact only' '
+test_expect_success 'config option matches exact only' '
 	cat >patch <<-\EOF &&
 
 		This-trailer: a
@@ -171,8 +170,7 @@ test_expect_failure 'config option matches exact only' '
 	test_cmp expected actual
 '
 
-# Matching currently uses the config key even if key value is different
-test_expect_failure 'config option matches exact only' '
+test_expect_success 'config option matches exact only' '
 	cat >patch <<-\EOF &&
 
 		Ticket: 1234
@@ -550,6 +548,17 @@ test_expect_success 'with config setup' '
 	test_cmp expected actual
 '
 
+test_expect_success 'trailer on commandline can be prefix of configured' '
+	cat >expected <<-\EOF &&
+
+		Acked-by: 10
+	EOF
+	git interpret-trailers --trailer "A=10" empty >actual &&
+	test_cmp expected actual
+'
+
+
+
 test_expect_success 'with config setup and ":=" as separators' '
 	git config trailer.separators ":=" &&
 	git config trailer.ack.key "Acked-by= " &&
diff --git a/trailer.c b/trailer.c
index 0db3bba3b1..b00b35ea0e 100644
--- a/trailer.c
+++ b/trailer.c
@@ -605,14 +605,18 @@ static int token_matches_conf(const char *tok, const struct conf_info *conf, siz
 	return conf->key ? !strncasecmp(tok, conf->key, tok_len) : 0;
 }
 
-static const struct conf_info *lookup_conf_for_tok(const struct strbuf *tok)
+static const struct conf_info *lookup_conf_for_tok(const struct strbuf *tok, int strict)
 {
 	struct conf_info_item *item;
 	struct list_head *pos;
 
 	list_for_each(pos, &conf_head) {
 		item = list_entry(pos, struct conf_info_item, list);
-		if (token_matches_conf(tok->buf, &item->conf, tok->len)) {
+		if (strict) {
+			const char *match = item->conf.key ? item->conf.key : item->conf.name;
+			if (!strcasecmp(match, tok->buf))
+				return &item->conf;
+		} else if (token_matches_conf(tok->buf, &item->conf, tok->len)) {
 			return &item->conf;
 		}
 	}
@@ -750,7 +754,7 @@ static void process_command_line_args(struct list_head *arg_head,
 		} else {
 			parse_trailer(&tok, &val, NULL, tr->text,
 				      separator_pos);
-			conf = lookup_conf_for_tok(&tok);
+			conf = lookup_conf_for_tok(&tok, 0);
 			add_arg_item(arg_head,
 				     strbuf_detach(&tok, NULL),
 				     strbuf_detach(&val, NULL),
@@ -1025,7 +1029,7 @@ static size_t process_input_file(FILE *outfile,
 			const struct conf_info *conf;
 			parse_trailer(&tok, &val, &sep, trailer,
 				      separator_pos);
-			conf = lookup_conf_for_tok(&tok);
+			conf = lookup_conf_for_tok(&tok, 1);
 			if (opts->unfold)
 				unfold_value(&val);
 			add_trailer_item(head,
@@ -1220,7 +1224,7 @@ static void format_trailer_info(struct strbuf *out,
 			const struct conf_info *conf;
 
 			parse_trailer(&tok, &val, NULL, trailer, separator_pos);
-			conf = lookup_conf_for_tok(&tok);
+			conf = lookup_conf_for_tok(&tok, 1);
 			if (!opts->filter ||
 			    opts->filter(&tok, conf ? conf->name : NULL, opts->filter_data)) {
 				if (opts->unfold)

diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 42544fb07a0..bf9b30ff3d6 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -723,7 +723,12 @@ test_expect_success '%(trailers:key=foo,valueonly) shows only value' '
 
 test_expect_success 'pretty format %(trailers:separator) changes separator' '
 	git log --no-walk --pretty=format:"X%(trailers:separator=%x00,unfold)X" >actual &&
-	printf "XSigned-off-by: A U Thor <author@example.com>\0Acked-by: A U Thor <author@example.com>\0[ v2 updated patch description ]\0Signed-off-by: A U Thor <author@example.com>X" >expect &&
+	(
+		printf "XSigned-off-by: A U Thor <author@example.com>\0" &&
+		printf "Acked-by: A U Thor <author@example.com>\0" &&
+		printf "[ v2 updated patch description ]\0" &&
+		printf "Signed-off-by: A U Thor <author@example.com>X"
+	) >expect &&
 	test_cmp expect actual
 '
 

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index 84bbc7439a6..66dfa122361 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -252,7 +252,15 @@ endif::git-rev-list[]
 			  interpreted by
 			  linkgit:git-interpret-trailers[1]. The
 			  `trailers` string may be followed by a colon
-			  and zero or more comma-separated options:
+			  and zero or more comma-separated options.
+			  If any option is provided multiple times the
+			  last occurance wins.
++
+The boolean options accept an optional value `[=<BOOL>]`. The values
+`true`, `false`, `on`, `off` etc. are all accepted. See the "boolean"
+sub-section in "EXAMPLES" in linkgit:git-config[1]. If a boolean
+option is given with no value, it's enabled.
++
 ** 'key=<K>': only show trailers with specified key. Matching is done
    case-insensitively and trailing colon is optional. If option is
    given multiple times trailer lines matching any of the keys are
@@ -261,27 +269,21 @@ endif::git-rev-list[]
    desired it can be disabled with `only=false`.  E.g.,
    `%(trailers:key=Reviewed-by)` shows trailer lines with key
    `Reviewed-by`.
-** 'only[=val]': select whether non-trailer lines from the trailer
-   block should be included. The `only` keyword may optionally be
-   followed by an equal sign and one of `true`, `on`, `yes` to omit or
-   `false`, `off`, `no` to show the non-trailer lines. If option is
-   given without value it is enabled. If given multiple times the last
-   value is used.
+** 'only[=BOOL]': select whether non-trailer lines from the trailer
+   block should be included.
 ** 'separator=<SEP>': specify a separator inserted between trailer
    lines. When this option is not given each trailer line is
    terminated with a line feed character. The string SEP may contain
    the literal formatting codes described above. To use comma as
    separator one must use `%x2C` as it would otherwise be parsed as
-   next option. If separator option is given multiple times only the
-   last one is used. E.g., `%(trailers:key=Ticket,separator=%x2C )`
+   next option. E.g., `%(trailers:key=Ticket,separator=%x2C )`
    shows all trailer lines whose key is "Ticket" separated by a comma
    and a space.
-** 'unfold[=val]': make it behave as if interpret-trailer's `--unfold`
-   option was given. In same way as to for `only` it can be followed
-   by an equal sign and explicit value. E.g.,
+** 'unfold[=BOOL]': make it behave as if interpret-trailer's `--unfold`
+   option was given. E.g.,
    `%(trailers:only,unfold=true)` unfolds and shows all trailer lines.
-** 'valueonly[=val]': skip over the key part of the trailer line and only
-   show the value part. Also this optionally allows explicit value.
+** 'valueonly[=BOOL]': skip over the key part of the trailer line and only
+   show the value part.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will

Documentation/pretty-formats.txt, pretty.c, t/t4205-log-pretty-formats.sh, trailer.c, trailer.h

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index 66dfa122361..bf35f7cf219 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -282,8 +282,8 @@ option is given with no value, it's enabled.
 ** 'unfold[=BOOL]': make it behave as if interpret-trailer's `--unfold`
    option was given. E.g.,
    `%(trailers:only,unfold=true)` unfolds and shows all trailer lines.
-** 'valueonly[=BOOL]': skip over the key part of the trailer line and only
-   show the value part.
+** 'keyonly[=BOOL]': only show the key part of the trailer.
+** 'valueonly[=BOOL]': only show the value part of the trailer.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will
diff --git a/pretty.c b/pretty.c
index 7a7708a0ea7..1237ee0e45d 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1451,6 +1451,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 					opts.separator = &sepbuf;
 				} else if (!match_placeholder_bool_arg(arg, "only", &arg, &opts.only_trailers) &&
 					   !match_placeholder_bool_arg(arg, "unfold", &arg, &opts.unfold) &&
+					   !match_placeholder_bool_arg(arg, "keyonly", &arg, &opts.key_only) &&
 					   !match_placeholder_bool_arg(arg, "valueonly", &arg, &opts.value_only))
 					break;
 			}
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index cb09a13249e..4c9f6eb7946 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -715,6 +715,22 @@ test_expect_success '%(trailers:key) without value is error' '
 	test_cmp expect actual
 '
 
+test_expect_success '%(trailers:keyonly) shows only keys' '
+	git log --no-walk --pretty="format:%(trailers:keyonly)" >actual &&
+	test_write_lines \
+		"Signed-off-by" \
+		"Acked-by" \
+		"[ v2 updated patch description ]" \
+		"Signed-off-by" >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success '%(trailers:key=foo,keyonly) shows only key' '
+	git log --no-walk --pretty="format:%(trailers:key=Acked-by,keyonly)" >actual &&
+	echo "Acked-by" >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success '%(trailers:key=foo,valueonly) shows only value' '
 	git log --no-walk --pretty="format:%(trailers:key=Acked-by,valueonly)" >actual &&
 	echo "A U Thor <author@example.com>" >expect &&
@@ -732,6 +748,12 @@ test_expect_success '%(trailers:valueonly) shows only values' '
 	test_cmp expect actual
 '
 
+test_expect_success '%(trailers:key=foo,keyonly,valueonly) shows nothing' '
+	git log --no-walk --pretty="format:%(trailers:key=Acked-by,keyonly,valueonly)" >actual &&
+	echo >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'pretty format %(trailers:separator) changes separator' '
 	git log --no-walk --pretty=format:"X%(trailers:separator=%x00)X" >actual &&
 	(
@@ -754,7 +776,7 @@ test_expect_success 'pretty format %(trailers:separator=X,unfold) changes separa
 	test_cmp expect actual
 '
 
-test_expect_success 'pretty format %(trailers) combining separator/key/valueonly' '
+test_expect_success 'pretty format %(trailers) combining separator/key/keyonly/valueonly' '
 	git commit --allow-empty -F - <<-\EOF &&
 	Important fix
 
@@ -781,6 +803,13 @@ test_expect_success 'pretty format %(trailers) combining separator/key/valueonly
 		"Does not close any tickets" \
 		"Another fix #567, #890" \
 		"Important fix #1234" >expect &&
+	test_cmp expect actual &&
+
+	git log --pretty="%s% (trailers:separator=%x2c%x20,key=Closes,keyonly)" HEAD~3.. >actual &&
+	test_write_lines \
+		"Does not close any tickets" \
+		"Another fix Closes, Closes" \
+		"Important fix Closes" >expect &&
 	test_cmp expect actual
 '
 
diff --git a/trailer.c b/trailer.c
index d2d01015b1d..889b419a4f6 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1132,7 +1132,7 @@ static void format_trailer_info(struct strbuf *out,
 
 	/* If we want the whole block untouched, we can take the fast path. */
 	if (!opts->only_trailers && !opts->unfold && !opts->filter &&
-	    !opts->separator && !opts->value_only) {
+	    !opts->separator && !opts->key_only && !opts->value_only) {
 		strbuf_add(out, info->trailer_start,
 			   info->trailer_end - info->trailer_start);
 		return;
@@ -1154,8 +1154,11 @@ static void format_trailer_info(struct strbuf *out,
 				if (opts->separator && out->len != origlen)
 					strbuf_addbuf(out, opts->separator);
 				if (!opts->value_only)
-					strbuf_addf(out, "%s: ", tok.buf);
-				strbuf_addbuf(out, &val);
+					strbuf_addbuf(out, &tok);
+				if (!opts->key_only && !opts->value_only)
+					strbuf_addstr(out, ": ");
+				if (!opts->key_only)
+					strbuf_addbuf(out, &val);
 				if (!opts->separator)
 					strbuf_addch(out, '\n');
 			}
diff --git a/trailer.h b/trailer.h
index cd93e7ddea7..d2f28776be6 100644
--- a/trailer.h
+++ b/trailer.h
@@ -71,6 +71,7 @@ struct process_trailer_options {
 	int only_input;
 	int unfold;
 	int no_divider;
+	int key_only;
 	int value_only;
 	const struct strbuf *separator;
 	int (*filter)(const struct strbuf *, void *);

diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 204c149d5a4..5e5452212d2 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -717,7 +717,12 @@ test_expect_success '%(trailers:key=foo,valueonly) shows only value' '
 
 test_expect_success 'pretty format %(trailers:separator) changes separator' '
 	git log --no-walk --pretty=format:"X%(trailers:separator=%x00,unfold)X" >actual &&
-	printf "XSigned-off-by: A U Thor <author@example.com>\0Acked-by: A U Thor <author@example.com>\0[ v2 updated patch description ]\0Signed-off-by: A U Thor <author@example.com>X" >expect &&
+	(
+		printf "XSigned-off-by: A U Thor <author@example.com>\0" &&
+		printf "Acked-by: A U Thor <author@example.com>\0" &&
+		printf "[ v2 updated patch description ]\0" &&
+		printf "Signed-off-by: A U Thor <author@example.com>X"
+	) >expect &&
 	test_cmp expect actual
 '
 

t/t4205-log-pretty-formats.sh, trailer.c

diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 5e5452212d2..cb09a13249e 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -605,6 +605,12 @@ test_expect_success 'pretty format %(trailers) shows trailers' '
 	test_cmp expect actual
 '
 
+test_expect_success 'pretty format %(trailers:) enables no options' '
+	git log --no-walk --pretty="%(trailers:)" >actual &&
+	# "expect" the same as the test above
+	test_cmp expect actual
+'
+
 test_expect_success '%(trailers:only) shows only "key: value" trailers' '
 	git log --no-walk --pretty="%(trailers:only)" >actual &&
 	{
@@ -715,7 +721,29 @@ test_expect_success '%(trailers:key=foo,valueonly) shows only value' '
 	test_cmp expect actual
 '
 
+test_expect_success '%(trailers:valueonly) shows only values' '
+	git log --no-walk --pretty="format:%(trailers:valueonly)" >actual &&
+	test_write_lines \
+		"A U Thor <author@example.com>" \
+		"A U Thor <author@example.com>" \
+		"[ v2 updated patch description ]" \
+		"A U Thor" \
+		"  <author@example.com>" >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'pretty format %(trailers:separator) changes separator' '
+	git log --no-walk --pretty=format:"X%(trailers:separator=%x00)X" >actual &&
+	(
+		printf "XSigned-off-by: A U Thor <author@example.com>\0" &&
+		printf "Acked-by: A U Thor <author@example.com>\0" &&
+		printf "[ v2 updated patch description ]\0" &&
+		printf "Signed-off-by: A U Thor\n  <author@example.com>X"
+	) >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'pretty format %(trailers:separator=X,unfold) changes separator' '
 	git log --no-walk --pretty=format:"X%(trailers:separator=%x00,unfold)X" >actual &&
 	(
 		printf "XSigned-off-by: A U Thor <author@example.com>\0" &&
diff --git a/trailer.c b/trailer.c
index 3f7391d793c..d2d01015b1d 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1131,7 +1131,8 @@ static void format_trailer_info(struct strbuf *out,
 	size_t i;
 
 	/* If we want the whole block untouched, we can take the fast path. */
-	if (!opts->only_trailers && !opts->unfold && !opts->filter && !opts->separator) {
+	if (!opts->only_trailers && !opts->unfold && !opts->filter &&
+	    !opts->separator && !opts->value_only) {
 		strbuf_add(out, info->trailer_start,
 			   info->trailer_end - info->trailer_start);
 		return;

diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 204c149d5a4..5e5452212d2 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -717,7 +717,12 @@ test_expect_success '%(trailers:key=foo,valueonly) shows only value' '
 
 test_expect_success 'pretty format %(trailers:separator) changes separator' '
 	git log --no-walk --pretty=format:"X%(trailers:separator=%x00,unfold)X" >actual &&
-	printf "XSigned-off-by: A U Thor <author@example.com>\0Acked-by: A U Thor <author@example.com>\0[ v2 updated patch description ]\0Signed-off-by: A U Thor <author@example.com>X" >expect &&
+	(
+		printf "XSigned-off-by: A U Thor <author@example.com>\0" &&
+		printf "Acked-by: A U Thor <author@example.com>\0" &&
+		printf "[ v2 updated patch description ]\0" &&
+		printf "Signed-off-by: A U Thor <author@example.com>X"
+	) >expect &&
 	test_cmp expect actual
 '
 

Documentation/pretty-formats.txt, pretty.c, t/t4205-log-pretty-formats.sh, trailer.c, trailer.h

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index 5eac36500d4..6b59e28d444 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -284,6 +284,10 @@ option is given with no value, it's enabled.
    `%(trailers:only,unfold=true)` unfolds and shows all trailer lines.
 ** 'keyonly[=<BOOL>]': only show the key part of the trailer.
 ** 'valueonly[=<BOOL>]': only show the value part of the trailer.
+** 'key_value_separator=<SEP>': specify a separator inserted between
+   trailer lines. When this option is not given each trailer key-value
+   pair is separated by ": ". Otherwise it shares the same semantics
+   as 'separator=<SEP>' above.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will
diff --git a/pretty.c b/pretty.c
index 1237ee0e45d..05eef7fda0b 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1418,6 +1418,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
 		struct string_list filter_list = STRING_LIST_INIT_NODUP;
 		struct strbuf sepbuf = STRBUF_INIT;
+		struct strbuf kvsepbuf = STRBUF_INIT;
 		size_t ret = 0;
 
 		opts.no_divider = 1;
@@ -1449,6 +1450,14 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 					strbuf_expand(&sepbuf, fmt, strbuf_expand_literal_cb, NULL);
 					free(fmt);
 					opts.separator = &sepbuf;
+				} else if (match_placeholder_arg_value(arg, "key_value_separator", &arg, &argval, &arglen)) {
+					char *fmt;
+
+					strbuf_reset(&kvsepbuf);
+					fmt = xstrndup(argval, arglen);
+					strbuf_expand(&kvsepbuf, fmt, strbuf_expand_literal_cb, NULL);
+					free(fmt);
+					opts.key_value_separator = &kvsepbuf;
 				} else if (!match_placeholder_bool_arg(arg, "only", &arg, &opts.only_trailers) &&
 					   !match_placeholder_bool_arg(arg, "unfold", &arg, &opts.unfold) &&
 					   !match_placeholder_bool_arg(arg, "keyonly", &arg, &opts.key_only) &&
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 4c9f6eb7946..749bc1431ac 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -776,6 +776,39 @@ test_expect_success 'pretty format %(trailers:separator=X,unfold) changes separa
 	test_cmp expect actual
 '
 
+test_expect_success 'pretty format %(trailers:key_value_separator) changes key-value separator' '
+	git log --no-walk --pretty=format:"X%(trailers:key_value_separator=%x00)X" >actual &&
+	(
+		printf "XSigned-off-by\0A U Thor <author@example.com>\n" &&
+		printf "Acked-by\0A U Thor <author@example.com>\n" &&
+		printf "[ v2 updated patch description ]\n" &&
+		printf "Signed-off-by\0A U Thor\n  <author@example.com>\nX"
+	) >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'pretty format %(trailers:key_value_separator,unfold) changes key-value separator' '
+	git log --no-walk --pretty=format:"X%(trailers:key_value_separator=%x00,unfold)X" >actual &&
+	(
+		printf "XSigned-off-by\0A U Thor <author@example.com>\n" &&
+		printf "Acked-by\0A U Thor <author@example.com>\n" &&
+		printf "[ v2 updated patch description ]\n" &&
+		printf "Signed-off-by\0A U Thor <author@example.com>\nX"
+	) >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'pretty format %(trailers:separator,key_value_separator) changes both separators' '
+	git log --no-walk --pretty=format:"%(trailers:separator=%x00,key_value_separator=%x00%x00,unfold)" >actual &&
+	(
+		printf "Signed-off-by\0\0A U Thor <author@example.com>\0" &&
+		printf "Acked-by\0\0A U Thor <author@example.com>\0" &&
+		printf "[ v2 updated patch description ]\0" &&
+		printf "Signed-off-by\0\0A U Thor <author@example.com>"
+	) >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'pretty format %(trailers) combining separator/key/keyonly/valueonly' '
 	git commit --allow-empty -F - <<-\EOF &&
 	Important fix
diff --git a/trailer.c b/trailer.c
index 889b419a4f6..249ed618ed8 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1132,7 +1132,8 @@ static void format_trailer_info(struct strbuf *out,
 
 	/* If we want the whole block untouched, we can take the fast path. */
 	if (!opts->only_trailers && !opts->unfold && !opts->filter &&
-	    !opts->separator && !opts->key_only && !opts->value_only) {
+	    !opts->separator && !opts->key_only && !opts->value_only &&
+	    !opts->key_value_separator) {
 		strbuf_add(out, info->trailer_start,
 			   info->trailer_end - info->trailer_start);
 		return;
@@ -1155,8 +1156,12 @@ static void format_trailer_info(struct strbuf *out,
 					strbuf_addbuf(out, opts->separator);
 				if (!opts->value_only)
 					strbuf_addbuf(out, &tok);
-				if (!opts->key_only && !opts->value_only)
-					strbuf_addstr(out, ": ");
+				if (!opts->key_only && !opts->value_only) {
+					if (opts->key_value_separator)
+						strbuf_addbuf(out, opts->key_value_separator);
+					else
+						strbuf_addstr(out, ": ");
+				}
 				if (!opts->key_only)
 					strbuf_addbuf(out, &val);
 				if (!opts->separator)
diff --git a/trailer.h b/trailer.h
index d2f28776be6..795d2fccfd9 100644
--- a/trailer.h
+++ b/trailer.h
@@ -74,6 +74,7 @@ struct process_trailer_options {
 	int key_only;
 	int value_only;
 	const struct strbuf *separator;
+	const struct strbuf *key_value_separator;
 	int (*filter)(const struct strbuf *, void *);
 	void *filter_data;
 };

Documentation/pretty-formats.txt, pretty.c, t/t4205-log-pretty-formats.sh, trailer.c, trailer.h

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index 973b6c7d482..5eac36500d4 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -282,8 +282,8 @@ option is given with no value, it's enabled.
 ** 'unfold[=<BOOL>]': make it behave as if interpret-trailer's `--unfold`
    option was given. E.g.,
    `%(trailers:only,unfold=true)` unfolds and shows all trailer lines.
-** 'valueonly[=<BOOL>]': skip over the key part of the trailer line and only
-   show the value part.
+** 'keyonly[=<BOOL>]': only show the key part of the trailer.
+** 'valueonly[=<BOOL>]': only show the value part of the trailer.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will
diff --git a/pretty.c b/pretty.c
index 7a7708a0ea7..1237ee0e45d 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1451,6 +1451,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 					opts.separator = &sepbuf;
 				} else if (!match_placeholder_bool_arg(arg, "only", &arg, &opts.only_trailers) &&
 					   !match_placeholder_bool_arg(arg, "unfold", &arg, &opts.unfold) &&
+					   !match_placeholder_bool_arg(arg, "keyonly", &arg, &opts.key_only) &&
 					   !match_placeholder_bool_arg(arg, "valueonly", &arg, &opts.value_only))
 					break;
 			}
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index cb09a13249e..4c9f6eb7946 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -715,6 +715,22 @@ test_expect_success '%(trailers:key) without value is error' '
 	test_cmp expect actual
 '
 
+test_expect_success '%(trailers:keyonly) shows only keys' '
+	git log --no-walk --pretty="format:%(trailers:keyonly)" >actual &&
+	test_write_lines \
+		"Signed-off-by" \
+		"Acked-by" \
+		"[ v2 updated patch description ]" \
+		"Signed-off-by" >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success '%(trailers:key=foo,keyonly) shows only key' '
+	git log --no-walk --pretty="format:%(trailers:key=Acked-by,keyonly)" >actual &&
+	echo "Acked-by" >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success '%(trailers:key=foo,valueonly) shows only value' '
 	git log --no-walk --pretty="format:%(trailers:key=Acked-by,valueonly)" >actual &&
 	echo "A U Thor <author@example.com>" >expect &&
@@ -732,6 +748,12 @@ test_expect_success '%(trailers:valueonly) shows only values' '
 	test_cmp expect actual
 '
 
+test_expect_success '%(trailers:key=foo,keyonly,valueonly) shows nothing' '
+	git log --no-walk --pretty="format:%(trailers:key=Acked-by,keyonly,valueonly)" >actual &&
+	echo >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'pretty format %(trailers:separator) changes separator' '
 	git log --no-walk --pretty=format:"X%(trailers:separator=%x00)X" >actual &&
 	(
@@ -754,7 +776,7 @@ test_expect_success 'pretty format %(trailers:separator=X,unfold) changes separa
 	test_cmp expect actual
 '
 
-test_expect_success 'pretty format %(trailers) combining separator/key/valueonly' '
+test_expect_success 'pretty format %(trailers) combining separator/key/keyonly/valueonly' '
 	git commit --allow-empty -F - <<-\EOF &&
 	Important fix
 
@@ -781,6 +803,13 @@ test_expect_success 'pretty format %(trailers) combining separator/key/valueonly
 		"Does not close any tickets" \
 		"Another fix #567, #890" \
 		"Important fix #1234" >expect &&
+	test_cmp expect actual &&
+
+	git log --pretty="%s% (trailers:separator=%x2c%x20,key=Closes,keyonly)" HEAD~3.. >actual &&
+	test_write_lines \
+		"Does not close any tickets" \
+		"Another fix Closes, Closes" \
+		"Important fix Closes" >expect &&
 	test_cmp expect actual
 '
 
diff --git a/trailer.c b/trailer.c
index d2d01015b1d..889b419a4f6 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1132,7 +1132,7 @@ static void format_trailer_info(struct strbuf *out,
 
 	/* If we want the whole block untouched, we can take the fast path. */
 	if (!opts->only_trailers && !opts->unfold && !opts->filter &&
-	    !opts->separator && !opts->value_only) {
+	    !opts->separator && !opts->key_only && !opts->value_only) {
 		strbuf_add(out, info->trailer_start,
 			   info->trailer_end - info->trailer_start);
 		return;
@@ -1154,8 +1154,11 @@ static void format_trailer_info(struct strbuf *out,
 				if (opts->separator && out->len != origlen)
 					strbuf_addbuf(out, opts->separator);
 				if (!opts->value_only)
-					strbuf_addf(out, "%s: ", tok.buf);
-				strbuf_addbuf(out, &val);
+					strbuf_addbuf(out, &tok);
+				if (!opts->key_only && !opts->value_only)
+					strbuf_addstr(out, ": ");
+				if (!opts->key_only)
+					strbuf_addbuf(out, &val);
 				if (!opts->separator)
 					strbuf_addch(out, '\n');
 			}
diff --git a/trailer.h b/trailer.h
index cd93e7ddea7..d2f28776be6 100644
--- a/trailer.h
+++ b/trailer.h
@@ -71,6 +71,7 @@ struct process_trailer_options {
 	int only_input;
 	int unfold;
 	int no_divider;
+	int key_only;
 	int value_only;
 	const struct strbuf *separator;
 	int (*filter)(const struct strbuf *, void *);

t/t4205-log-pretty-formats.sh, trailer.c

diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 5e5452212d2..cb09a13249e 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -605,6 +605,12 @@ test_expect_success 'pretty format %(trailers) shows trailers' '
 	test_cmp expect actual
 '
 
+test_expect_success 'pretty format %(trailers:) enables no options' '
+	git log --no-walk --pretty="%(trailers:)" >actual &&
+	# "expect" the same as the test above
+	test_cmp expect actual
+'
+
 test_expect_success '%(trailers:only) shows only "key: value" trailers' '
 	git log --no-walk --pretty="%(trailers:only)" >actual &&
 	{
@@ -715,7 +721,29 @@ test_expect_success '%(trailers:key=foo,valueonly) shows only value' '
 	test_cmp expect actual
 '
 
+test_expect_success '%(trailers:valueonly) shows only values' '
+	git log --no-walk --pretty="format:%(trailers:valueonly)" >actual &&
+	test_write_lines \
+		"A U Thor <author@example.com>" \
+		"A U Thor <author@example.com>" \
+		"[ v2 updated patch description ]" \
+		"A U Thor" \
+		"  <author@example.com>" >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'pretty format %(trailers:separator) changes separator' '
+	git log --no-walk --pretty=format:"X%(trailers:separator=%x00)X" >actual &&
+	(
+		printf "XSigned-off-by: A U Thor <author@example.com>\0" &&
+		printf "Acked-by: A U Thor <author@example.com>\0" &&
+		printf "[ v2 updated patch description ]\0" &&
+		printf "Signed-off-by: A U Thor\n  <author@example.com>X"
+	) >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'pretty format %(trailers:separator=X,unfold) changes separator' '
 	git log --no-walk --pretty=format:"X%(trailers:separator=%x00,unfold)X" >actual &&
 	(
 		printf "XSigned-off-by: A U Thor <author@example.com>\0" &&
diff --git a/trailer.c b/trailer.c
index 3f7391d793c..d2d01015b1d 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1131,7 +1131,8 @@ static void format_trailer_info(struct strbuf *out,
 	size_t i;
 
 	/* If we want the whole block untouched, we can take the fast path. */
-	if (!opts->only_trailers && !opts->unfold && !opts->filter && !opts->separator) {
+	if (!opts->only_trailers && !opts->unfold && !opts->filter &&
+	    !opts->separator && !opts->value_only) {
 		strbuf_add(out, info->trailer_start,
 			   info->trailer_end - info->trailer_start);
 		return;

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index 84bbc7439a6..973b6c7d482 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -252,7 +252,15 @@ endif::git-rev-list[]
 			  interpreted by
 			  linkgit:git-interpret-trailers[1]. The
 			  `trailers` string may be followed by a colon
-			  and zero or more comma-separated options:
+			  and zero or more comma-separated options.
+			  If any option is provided multiple times the
+			  last occurance wins.
++
+The boolean options accept an optional value `[=<BOOL>]`. The values
+`true`, `false`, `on`, `off` etc. are all accepted. See the "boolean"
+sub-section in "EXAMPLES" in linkgit:git-config[1]. If a boolean
+option is given with no value, it's enabled.
++
 ** 'key=<K>': only show trailers with specified key. Matching is done
    case-insensitively and trailing colon is optional. If option is
    given multiple times trailer lines matching any of the keys are
@@ -261,27 +269,21 @@ endif::git-rev-list[]
    desired it can be disabled with `only=false`.  E.g.,
    `%(trailers:key=Reviewed-by)` shows trailer lines with key
    `Reviewed-by`.
-** 'only[=val]': select whether non-trailer lines from the trailer
-   block should be included. The `only` keyword may optionally be
-   followed by an equal sign and one of `true`, `on`, `yes` to omit or
-   `false`, `off`, `no` to show the non-trailer lines. If option is
-   given without value it is enabled. If given multiple times the last
-   value is used.
+** 'only[=<BOOL>]': select whether non-trailer lines from the trailer
+   block should be included.
 ** 'separator=<SEP>': specify a separator inserted between trailer
    lines. When this option is not given each trailer line is
    terminated with a line feed character. The string SEP may contain
    the literal formatting codes described above. To use comma as
    separator one must use `%x2C` as it would otherwise be parsed as
-   next option. If separator option is given multiple times only the
-   last one is used. E.g., `%(trailers:key=Ticket,separator=%x2C )`
+   next option. E.g., `%(trailers:key=Ticket,separator=%x2C )`
    shows all trailer lines whose key is "Ticket" separated by a comma
    and a space.
-** 'unfold[=val]': make it behave as if interpret-trailer's `--unfold`
-   option was given. In same way as to for `only` it can be followed
-   by an equal sign and explicit value. E.g.,
+** 'unfold[=<BOOL>]': make it behave as if interpret-trailer's `--unfold`
+   option was given. E.g.,
    `%(trailers:only,unfold=true)` unfolds and shows all trailer lines.
-** 'valueonly[=val]': skip over the key part of the trailer line and only
-   show the value part. Also this optionally allows explicit value.
+** 'valueonly[=<BOOL>]': skip over the key part of the trailer line and only
+   show the value part.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will

Documentation/pretty-formats.txt, pretty.c, t/t4205-log-pretty-formats.sh, trailer.c, trailer.h

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index bf35f7cf219..17050a78245 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -284,6 +284,10 @@ option is given with no value, it's enabled.
    `%(trailers:only,unfold=true)` unfolds and shows all trailer lines.
 ** 'keyonly[=BOOL]': only show the key part of the trailer.
 ** 'valueonly[=BOOL]': only show the value part of the trailer.
+** 'key_value_separator=<SEP>': specify a separator inserted between
+   trailer lines. When this option is not given each trailer key-value
+   pair is separated by ": ". Otherwise it shares the same semantics
+   as 'separator=<SEP>' above.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will
diff --git a/pretty.c b/pretty.c
index 1237ee0e45d..05eef7fda0b 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1418,6 +1418,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
 		struct string_list filter_list = STRING_LIST_INIT_NODUP;
 		struct strbuf sepbuf = STRBUF_INIT;
+		struct strbuf kvsepbuf = STRBUF_INIT;
 		size_t ret = 0;
 
 		opts.no_divider = 1;
@@ -1449,6 +1450,14 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 					strbuf_expand(&sepbuf, fmt, strbuf_expand_literal_cb, NULL);
 					free(fmt);
 					opts.separator = &sepbuf;
+				} else if (match_placeholder_arg_value(arg, "key_value_separator", &arg, &argval, &arglen)) {
+					char *fmt;
+
+					strbuf_reset(&kvsepbuf);
+					fmt = xstrndup(argval, arglen);
+					strbuf_expand(&kvsepbuf, fmt, strbuf_expand_literal_cb, NULL);
+					free(fmt);
+					opts.key_value_separator = &kvsepbuf;
 				} else if (!match_placeholder_bool_arg(arg, "only", &arg, &opts.only_trailers) &&
 					   !match_placeholder_bool_arg(arg, "unfold", &arg, &opts.unfold) &&
 					   !match_placeholder_bool_arg(arg, "keyonly", &arg, &opts.key_only) &&
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 4c9f6eb7946..749bc1431ac 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -776,6 +776,39 @@ test_expect_success 'pretty format %(trailers:separator=X,unfold) changes separa
 	test_cmp expect actual
 '
 
+test_expect_success 'pretty format %(trailers:key_value_separator) changes key-value separator' '
+	git log --no-walk --pretty=format:"X%(trailers:key_value_separator=%x00)X" >actual &&
+	(
+		printf "XSigned-off-by\0A U Thor <author@example.com>\n" &&
+		printf "Acked-by\0A U Thor <author@example.com>\n" &&
+		printf "[ v2 updated patch description ]\n" &&
+		printf "Signed-off-by\0A U Thor\n  <author@example.com>\nX"
+	) >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'pretty format %(trailers:key_value_separator,unfold) changes key-value separator' '
+	git log --no-walk --pretty=format:"X%(trailers:key_value_separator=%x00,unfold)X" >actual &&
+	(
+		printf "XSigned-off-by\0A U Thor <author@example.com>\n" &&
+		printf "Acked-by\0A U Thor <author@example.com>\n" &&
+		printf "[ v2 updated patch description ]\n" &&
+		printf "Signed-off-by\0A U Thor <author@example.com>\nX"
+	) >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'pretty format %(trailers:separator,key_value_separator) changes both separators' '
+	git log --no-walk --pretty=format:"%(trailers:separator=%x00,key_value_separator=%x00%x00,unfold)" >actual &&
+	(
+		printf "Signed-off-by\0\0A U Thor <author@example.com>\0" &&
+		printf "Acked-by\0\0A U Thor <author@example.com>\0" &&
+		printf "[ v2 updated patch description ]\0" &&
+		printf "Signed-off-by\0\0A U Thor <author@example.com>"
+	) >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'pretty format %(trailers) combining separator/key/keyonly/valueonly' '
 	git commit --allow-empty -F - <<-\EOF &&
 	Important fix
diff --git a/trailer.c b/trailer.c
index 889b419a4f6..249ed618ed8 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1132,7 +1132,8 @@ static void format_trailer_info(struct strbuf *out,
 
 	/* If we want the whole block untouched, we can take the fast path. */
 	if (!opts->only_trailers && !opts->unfold && !opts->filter &&
-	    !opts->separator && !opts->key_only && !opts->value_only) {
+	    !opts->separator && !opts->key_only && !opts->value_only &&
+	    !opts->key_value_separator) {
 		strbuf_add(out, info->trailer_start,
 			   info->trailer_end - info->trailer_start);
 		return;
@@ -1155,8 +1156,12 @@ static void format_trailer_info(struct strbuf *out,
 					strbuf_addbuf(out, opts->separator);
 				if (!opts->value_only)
 					strbuf_addbuf(out, &tok);
-				if (!opts->key_only && !opts->value_only)
-					strbuf_addstr(out, ": ");
+				if (!opts->key_only && !opts->value_only) {
+					if (opts->key_value_separator)
+						strbuf_addbuf(out, opts->key_value_separator);
+					else
+						strbuf_addstr(out, ": ");
+				}
 				if (!opts->key_only)
 					strbuf_addbuf(out, &val);
 				if (!opts->separator)
diff --git a/trailer.h b/trailer.h
index d2f28776be6..795d2fccfd9 100644
--- a/trailer.h
+++ b/trailer.h
@@ -74,6 +74,7 @@ struct process_trailer_options {
 	int key_only;
 	int value_only;
 	const struct strbuf *separator;
+	const struct strbuf *key_value_separator;
 	int (*filter)(const struct strbuf *, void *);
 	void *filter_data;
 };

Documentation/pretty-formats.txt, pretty.c, t/t4205-log-pretty-formats.sh, trailer.c, trailer.h

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index 8e066594624..d080f0d2476 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -284,8 +284,8 @@ multiple times the last occurance wins.
 ** 'unfold[=bool]': make it behave as if interpret-trailer's `--unfold`
    option was given. E.g.,
    `%(trailers:only,unfold=true)` unfolds and shows all trailer lines.
-** 'valueonly[=bool]': skip over the key part of the trailer line and only
-   show the value part.
+** 'keyonly[=bool]': only show the key part of the trailer.
+** 'valueonly[=bool]': only show the value part of the trailer.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will
diff --git a/pretty.c b/pretty.c
index 3c374abffe5..590f37489f6 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1454,6 +1454,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 					opts.separator = &sepbuf;
 				} else if (!match_placeholder_bool_arg(arg, "only", &arg, &opts.only_trailers) &&
 					   !match_placeholder_bool_arg(arg, "unfold", &arg, &opts.unfold) &&
+					   !match_placeholder_bool_arg(arg, "keyonly", &arg, &opts.key_only) &&
 					   !match_placeholder_bool_arg(arg, "valueonly", &arg, &opts.value_only))
 					break;
 			}
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index bf9b30ff3d6..5dd080c19b2 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -715,12 +715,34 @@ test_expect_success '%(trailers:key) without value is error' '
 	test_cmp expect actual
 '
 
+test_expect_success '%(trailers:key=foo,keyonly) shows only keys' '
+	git log --no-walk --pretty="format:%(trailers:keyonly)" >actual &&
+	test_write_lines \
+		"Signed-off-by" \
+		"Acked-by" \
+		"[ v2 updated patch description ]" \
+		"Signed-off-by" >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success '%(trailers:key=foo,keyonly) shows only key' '
+	git log --no-walk --pretty="format:%(trailers:key=Acked-by,keyonly)" >actual &&
+	echo "Acked-by" >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success '%(trailers:key=foo,valueonly) shows only value' '
 	git log --no-walk --pretty="format:%(trailers:key=Acked-by,valueonly)" >actual &&
 	echo "A U Thor <author@example.com>" >expect &&
 	test_cmp expect actual
 '
 
+test_expect_success '%(trailers:key=foo,keyonly,valueonly) shows nothing' '
+	git log --no-walk --pretty="format:%(trailers:key=Acked-by,keyonly,valueonly)" >actual &&
+	echo >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'pretty format %(trailers:separator) changes separator' '
 	git log --no-walk --pretty=format:"X%(trailers:separator=%x00,unfold)X" >actual &&
 	(
@@ -732,7 +754,7 @@ test_expect_success 'pretty format %(trailers:separator) changes separator' '
 	test_cmp expect actual
 '
 
-test_expect_success 'pretty format %(trailers) combining separator/key/valueonly' '
+test_expect_success 'pretty format %(trailers) combining separator/key/keyonly/valueonly' '
 	git commit --allow-empty -F - <<-\EOF &&
 	Important fix
 
@@ -759,6 +781,13 @@ test_expect_success 'pretty format %(trailers) combining separator/key/valueonly
 		"Does not close any tickets" \
 		"Another fix #567, #890" \
 		"Important fix #1234" >expect &&
+	test_cmp expect actual &&
+
+	git log --pretty="%s% (trailers:separator=%x2c%x20,key=Closes,keyonly)" HEAD~3.. >actual &&
+	test_write_lines \
+		"Does not close any tickets" \
+		"Another fix Closes, Closes" \
+		"Important fix Closes" >expect &&
 	test_cmp expect actual
 '
 
diff --git a/trailer.c b/trailer.c
index b00b35ea0eb..40f31e4dfc2 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1233,8 +1233,11 @@ static void format_trailer_info(struct strbuf *out,
 				if (opts->separator && out->len != origlen)
 					strbuf_addbuf(out, opts->separator);
 				if (!opts->value_only)
-					strbuf_addf(out, "%s: ", tok.buf);
-				strbuf_addbuf(out, &val);
+					strbuf_addstr(out, tok.buf);
+				if (!opts->key_only && !opts->value_only)
+					strbuf_addstr(out, ": ");
+				if (!opts->key_only)
+					strbuf_addbuf(out, &val);
 				if (!opts->separator)
 					strbuf_addch(out, '\n');
 			}
diff --git a/trailer.h b/trailer.h
index aad856da8c1..d4507b4ef2a 100644
--- a/trailer.h
+++ b/trailer.h
@@ -71,9 +71,11 @@ struct process_trailer_options {
 	int only_input;
 	int unfold;
 	int no_divider;
+	int key_only;
 	int value_only;
 	int canonicalize;
 	const struct strbuf *separator;
+	const struct strbuf *key_value_separator;
 	int (*filter)(const struct strbuf *, const char *alias, void *);
 	void *filter_data;
 };

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index 54f793d424f..8e066594624 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -252,7 +252,14 @@ endif::git-rev-list[]
 			  interpreted by
 			  linkgit:git-interpret-trailers[1]. The
 			  `trailers` string may be followed by a colon
-			  and zero or more comma-separated options:
+			  and zero or more comma-separated options.
++
+The boolean options accept an optional value. The values `true`,
+`false`, `on`, `off` etc. are all accepted. See the "boolean"
+sub-section in "EXAMPLES" in linkgit:git-config[1]. If a boolean
+option is given with no value it's enabled. If any option is provided
+multiple times the last occurance wins.
++
 ** 'key=<K>': only show trailers with specified key. Matching is done
    case-insensitively and trailing colon is optional. If option is
    given multiple times trailer lines matching any of the keys are
@@ -264,27 +271,21 @@ endif::git-rev-list[]
    desired it can be disabled with `only=false`.  E.g.,
    `%(trailers:key=Reviewed-by)` shows trailer lines with key
    `Reviewed-by`.
-** 'only[=val]': select whether non-trailer lines from the trailer
-   block should be included. The `only` keyword may optionally be
-   followed by an equal sign and one of `true`, `on`, `yes` to omit or
-   `false`, `off`, `no` to show the non-trailer lines. If option is
-   given without value it is enabled. If given multiple times the last
-   value is used.
+** 'only[=bool]': select whether non-trailer lines from the trailer
+   block should be included.
 ** 'separator=<SEP>': specify a separator inserted between trailer
    lines. When this option is not given each trailer line is
    terminated with a line feed character. The string SEP may contain
    the literal formatting codes described above. To use comma as
    separator one must use `%x2C` as it would otherwise be parsed as
-   next option. If separator option is given multiple times only the
-   last one is used. E.g., `%(trailers:key=Ticket,separator=%x2C )`
+   next option. E.g., `%(trailers:key=Ticket,separator=%x2C )`
    shows all trailer lines whose key is "Ticket" separated by a comma
    and a space.
-** 'unfold[=val]': make it behave as if interpret-trailer's `--unfold`
-   option was given. In same way as to for `only` it can be followed
-   by an equal sign and explicit value. E.g.,
+** 'unfold[=bool]': make it behave as if interpret-trailer's `--unfold`
+   option was given. E.g.,
    `%(trailers:only,unfold=true)` unfolds and shows all trailer lines.
-** 'valueonly[=val]': skip over the key part of the trailer line and only
-   show the value part. Also this optionally allows explicit value.
+** 'valueonly[=bool]': skip over the key part of the trailer line and only
+   show the value part.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will

pretty.c, t/t4205-log-pretty-formats.sh, trailer.c, trailer.h

diff --git a/pretty.c b/pretty.c
index 590f37489f6..d989a6ae712 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1426,6 +1426,8 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		opts.no_divider = 1;
 
 		if (*arg == ':') {
+			/* over-matches on %(trailers:), but that's OK */
+			opts.have_options = 1;
 			arg++;
 			for (;;) {
 				const char *argval;
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index 5dd080c19b2..e1100082b34 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -737,6 +737,17 @@ test_expect_success '%(trailers:key=foo,valueonly) shows only value' '
 	test_cmp expect actual
 '
 
+test_expect_success '%(trailers:valueonly) shows only values' '
+	git log --no-walk --pretty="format:%(trailers:valueonly)" >actual &&
+	test_write_lines \
+		"A U Thor <author@example.com>" \
+		"A U Thor <author@example.com>" \
+		"[ v2 updated patch description ]" \
+		"A U Thor" \
+		"  <author@example.com>" >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success '%(trailers:key=foo,keyonly,valueonly) shows nothing' '
 	git log --no-walk --pretty="format:%(trailers:key=Acked-by,keyonly,valueonly)" >actual &&
 	echo >expect &&
diff --git a/trailer.c b/trailer.c
index 40f31e4dfc2..da95e1f3c66 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1206,8 +1206,7 @@ static void format_trailer_info(struct strbuf *out,
 	size_t origlen = out->len;
 	size_t i;
 
-	/* If we want the whole block untouched, we can take the fast path. */
-	if (!opts->only_trailers && !opts->unfold && !opts->filter && !opts->separator) {
+	if (!opts->have_options) {
 		strbuf_add(out, info->trailer_start,
 			   info->trailer_end - info->trailer_start);
 		return;
diff --git a/trailer.h b/trailer.h
index d4507b4ef2a..e348c970ce7 100644
--- a/trailer.h
+++ b/trailer.h
@@ -65,6 +65,7 @@ struct new_trailer_item {
 };
 
 struct process_trailer_options {
+	int have_options;
 	int in_place;
 	int trim_empty;
 	int only_trailers;

Documentation/pretty-formats.txt, pretty.c, t/t4205-log-pretty-formats.sh, trailer.c

diff --git a/Documentation/pretty-formats.txt b/Documentation/pretty-formats.txt
index d080f0d2476..369d243eae9 100644
--- a/Documentation/pretty-formats.txt
+++ b/Documentation/pretty-formats.txt
@@ -286,6 +286,10 @@ multiple times the last occurance wins.
    `%(trailers:only,unfold=true)` unfolds and shows all trailer lines.
 ** 'keyonly[=bool]': only show the key part of the trailer.
 ** 'valueonly[=bool]': only show the value part of the trailer.
+** 'key_value_separator=<SEP>': specify a separator inserted between
+   trailer lines. When this option is not given each trailer key-value
+   pair separated by ": ". Otherwise it shares the same semantics as 
+   'separator=<SEP>' above.
 
 NOTE: Some placeholders may depend on other options given to the
 revision traversal engine. For example, the `%g*` reflog options will
diff --git a/pretty.c b/pretty.c
index d989a6ae712..dea77f2621a 100644
--- a/pretty.c
+++ b/pretty.c
@@ -1421,6 +1421,7 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 		struct process_trailer_options opts = PROCESS_TRAILER_OPTIONS_INIT;
 		struct string_list filter_list = STRING_LIST_INIT_NODUP;
 		struct strbuf sepbuf = STRBUF_INIT;
+		struct strbuf kvsepbuf = STRBUF_INIT;
 		size_t ret = 0;
 
 		opts.no_divider = 1;
@@ -1454,6 +1455,14 @@ static size_t format_commit_one(struct strbuf *sb, /* in UTF-8 */
 					strbuf_expand(&sepbuf, fmt, strbuf_expand_literal_cb, NULL);
 					free(fmt);
 					opts.separator = &sepbuf;
+				} else if (match_placeholder_arg_value(arg, "key_value_separator", &arg, &argval, &arglen)) {
+					char *fmt;
+
+					strbuf_reset(&kvsepbuf);
+					fmt = xstrndup(argval, arglen);
+					strbuf_expand(&kvsepbuf, fmt, strbuf_expand_literal_cb, NULL);
+					free(fmt);
+					opts.key_value_separator = &kvsepbuf;
 				} else if (!match_placeholder_bool_arg(arg, "only", &arg, &opts.only_trailers) &&
 					   !match_placeholder_bool_arg(arg, "unfold", &arg, &opts.unfold) &&
 					   !match_placeholder_bool_arg(arg, "keyonly", &arg, &opts.key_only) &&
diff --git a/t/t4205-log-pretty-formats.sh b/t/t4205-log-pretty-formats.sh
index e1100082b34..47b3f7d67c4 100755
--- a/t/t4205-log-pretty-formats.sh
+++ b/t/t4205-log-pretty-formats.sh
@@ -765,6 +765,28 @@ test_expect_success 'pretty format %(trailers:separator) changes separator' '
 	test_cmp expect actual
 '
 
+test_expect_success 'pretty format %(trailers:key_value_separator) changes key-value separator' '
+	git log --no-walk --pretty=format:"X%(trailers:key_value_separator=%x00,unfold)X" >actual &&
+	(
+		printf "XSigned-off-by\0A U Thor <author@example.com>\n" &&
+		printf "Acked-by\0A U Thor <author@example.com>\n" &&
+		printf "[ v2 updated patch description ]\n" &&
+		printf "Signed-off-by\0A U Thor <author@example.com>\nX"
+	) >expect &&
+	test_cmp expect actual
+'
+
+test_expect_success 'pretty format %(trailers:separator,key_value_separator) changes both separators' '
+	git log --no-walk --pretty=format:"%(trailers:separator=%x00,key_value_separator=%x00%x00,unfold)" >actual &&
+	(
+		printf "Signed-off-by\0\0A U Thor <author@example.com>\0" &&
+		printf "Acked-by\0\0A U Thor <author@example.com>\0" &&
+		printf "[ v2 updated patch description ]\0" &&
+		printf "Signed-off-by\0\0A U Thor <author@example.com>"
+	) >expect &&
+	test_cmp expect actual
+'
+
 test_expect_success 'pretty format %(trailers) combining separator/key/keyonly/valueonly' '
 	git commit --allow-empty -F - <<-\EOF &&
 	Important fix
diff --git a/trailer.c b/trailer.c
index da95e1f3c66..70a560647c1 100644
--- a/trailer.c
+++ b/trailer.c
@@ -1233,8 +1233,12 @@ static void format_trailer_info(struct strbuf *out,
 					strbuf_addbuf(out, opts->separator);
 				if (!opts->value_only)
 					strbuf_addstr(out, tok.buf);
-				if (!opts->key_only && !opts->value_only)
-					strbuf_addstr(out, ": ");
+				if (!opts->key_only && !opts->value_only) {
+					if (opts->key_value_separator)
+						strbuf_addbuf(out, opts->key_value_separator);
+					else
+						strbuf_addstr(out, ": ");
+				}
 				if (!opts->key_only)
 					strbuf_addbuf(out, &val);
 				if (!opts->separator)