format-patch: allow a non-integral version numbers

Usually we can only use `format-patch -v<n>` to generate integral
version numbers patches, but if we can provide `format-patch` with
non-integer versions numbers of patches, this may help us to send patches
such as "v1.1" versions sometimes.

Signed-off-by: ZheNing Hu <adlternative@gmail.com>

Documentation/git-format-patch.txt

@@ -215,12 +215,12 @@ populated with placeholder text.
 
 -v <n>::
 --reroll-count=<n>::
-	Mark the series as the <n>-th iteration of the topic. The
+	Mark the series as the specified version of the topic. The
 	output filenames have `v<n>` prepended to them, and the
 	subject prefix ("PATCH" by default, but configurable via the
 	`--subject-prefix` option) has ` v<n>` appended to it.  E.g.
-	`--reroll-count=4` may produce `v4-0001-add-makefile.patch`
-	file that has "Subject: [PATCH v4 1/20] Add makefile" in it.
+	`--reroll-count 4.4` may produce `v4.4-0001-add-makefile.patch`
+	file that has "Subject: [PATCH v4.4 1/20] Add makefile" in it.
 
 --to=<email>::
 	Add a `To:` header to the email headers. This is in addition

builtin/log.c

@@ -1662,13 +1662,13 @@ static void print_bases(struct base_tree_info *bases, FILE *file)
 	oidclr(&bases->base_commit);
 }
 
-static const char *diff_title(struct strbuf *sb, int reroll_count,
+static const char *diff_title(struct strbuf *sb, const char *reroll_count,
 		       const char *generic, const char *rerolled)
 {
-	if (reroll_count <= 0)
+	if (!reroll_count)
 		strbuf_addstr(sb, generic);
 	else /* RFC may be v0, so allow -v1 to diff against v0 */
-		strbuf_addf(sb, rerolled, reroll_count - 1);
+		strbuf_addf(sb, rerolled, "last version");
 	return sb->buf;
 }
 
@@ -1717,7 +1717,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	struct strbuf buf = STRBUF_INIT;
 	int use_patch_format = 0;
 	int quiet = 0;
-	int reroll_count = -1;
+	const char *reroll_count = NULL;
 	char *cover_from_description_arg = NULL;
 	char *branch_name = NULL;
 	char *base_commit = NULL;
@@ -1751,8 +1751,8 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			    N_("use <sfx> instead of '.patch'")),
 		OPT_INTEGER(0, "start-number", &start_number,
 			    N_("start numbering patches at <n> instead of 1")),
-		OPT_INTEGER('v', "reroll-count", &reroll_count,
-			    N_("mark the series as Nth re-roll")),
+		OPT_STRING('v', "reroll-count",&reroll_count, N_("reroll-count"),
+			    N_("mark the series as specified version re-roll")),
 		OPT_INTEGER(0, "filename-max-length", &fmt_patch_name_max,
 			    N_("max length of output filename")),
 		OPT_CALLBACK_F(0, "rfc", &rev, NULL,
@@ -1862,9 +1862,9 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	if (cover_from_description_arg)
 		cover_from_description_mode = parse_cover_from_description(cover_from_description_arg);
 
-	if (0 < reroll_count) {
+	if (reroll_count) {
 		struct strbuf sprefix = STRBUF_INIT;
-		strbuf_addf(&sprefix, "%s v%d",
+		strbuf_addf(&sprefix, "%s v%s",
 			    rev.subject_prefix, reroll_count);
 		rev.reroll_count = reroll_count;
 		rev.subject_prefix = strbuf_detach(&sprefix, NULL);
@@ -2080,7 +2080,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		rev.idiff_oid2 = get_commit_tree_oid(list[0]);
 		rev.idiff_title = diff_title(&idiff_title, reroll_count,
 					     _("Interdiff:"),
-					     _("Interdiff against v%d:"));
+					     _("Interdiff against %s:"));
 	}
 
 	if (creation_factor < 0)
@@ -2099,7 +2099,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 		rev.creation_factor = creation_factor;
 		rev.rdiff_title = diff_title(&rdiff_title, reroll_count,
 					     _("Range-diff:"),
-					     _("Range-diff against v%d:"));
+					     _("Range-diff against %s:"));
 	}
 
 	if (!signature) {

log-tree.c

@@ -369,8 +369,8 @@ void fmt_output_subject(struct strbuf *filename,
 	int start_len = filename->len;
 	int max_len = start_len + info->patch_name_max - (strlen(suffix) + 1);
 
-	if (0 < info->reroll_count)
-		strbuf_addf(filename, "v%d-", info->reroll_count);
+	if (info->reroll_count)
+		strbuf_addf(filename, "v%s-", info->reroll_count);
 	strbuf_addf(filename, "%04d-%s", nr, subject);
 
 	if (max_len < filename->len)

revision.h

@@ -235,7 +235,7 @@ struct rev_info {
 	const char	*mime_boundary;
 	const char	*patch_suffix;
 	int		numbered_files;
-	int		reroll_count;
+	const char	*reroll_count;
 	char		*message_id;
 	struct ident_split from_ident;
 	struct string_list *ref_message_ids;

t/t4014-format-patch.sh

@@ -372,10 +372,10 @@ test_expect_success 'filename limit applies only to basename' '
 
 test_expect_success 'reroll count' '
 	rm -fr patches &&
-	git format-patch -o patches --cover-letter --reroll-count 4 main..side >list &&
-	! grep -v "^patches/v4-000[0-3]-" list &&
+	git format-patch -o patches --cover-letter --reroll-count 4.4 main..side >list &&
+	! grep -v "^patches/v4.4-000[0-3]-" list &&
 	sed -n -e "/^Subject: /p" $(cat list) >subjects &&
-	! grep -v "^Subject: \[PATCH v4 [0-3]/3\] " subjects
+	! grep -v "^Subject: \[PATCH v4.4 [0-3]/3\] " subjects
 '
 
 test_expect_success 'reroll count (-v)' '
@@ -2252,7 +2252,7 @@ test_expect_success 'interdiff: cover-letter' '
 
 test_expect_success 'interdiff: reroll-count' '
 	git format-patch --cover-letter --interdiff=boop~2 -v2 -1 boop &&
-	test_i18ngrep "^Interdiff ..* v1:$" v2-0000-cover-letter.patch
+	test_i18ngrep "^Interdiff ..* last version:$" v2-0000-cover-letter.patch
 '
 
 test_expect_success 'interdiff: solo-patch' '