Merge branch 'dd/format-patch-rfc-updates' into next

"git format-patch --rfc --subject-prefix=<foo>" used to ignore the
"--subject-prefix" option and used "[RFC PATCH]"; now we will add
"RFC" prefix to whatever subject prefix is specified.

This is a backward compatible change that may deserve a note.

* dd/format-patch-rfc-updates:
  format-patch: --rfc honors what --subject-prefix sets

Documentation/git-format-patch.txt

@@ -221,9 +221,15 @@ populated with placeholder text.
 
 --subject-prefix=<subject prefix>::
 	Instead of the standard '[PATCH]' prefix in the subject
-	line, instead use '[<subject prefix>]'. This
+	line, instead use '[<subject prefix>]'. This can be used
-	allows for useful naming of a patch series, and can be
+	to name a patch series, and can be combined with the
-	combined with the `--numbered` option.
+	`--numbered` option.
++
+The configuration variable `format.subjectPrefix` may also be used
+to configure a subject prefix to apply to a given repository for
+all patches. This is often useful on mailing lists which receive
+patches for several repositories and can be used to disambiguate
+the patches (with a value of e.g. "PATCH my-project").
 
 --filename-max-length=<n>::
 	Instead of the standard 64 bytes, chomp the generated output
@@ -233,9 +239,9 @@ populated with placeholder text.
 	variable, or 64 if unconfigured.
 
 --rfc::
-	Alias for `--subject-prefix="RFC PATCH"`. RFC means "Request For
+	Prepends "RFC" to the subject prefix (producing "RFC PATCH" by
-	Comments"; use this when sending an experimental patch for
+	default). RFC means "Request For Comments"; use this when sending
-	discussion rather than application.
+	an experimental patch for discussion rather than application.
 
 -v <n>::
 --reroll-count=<n>::

builtin/log.c

@@ -1480,17 +1480,14 @@ static int subject_prefix = 0;
 static int subject_prefix_callback(const struct option *opt, const char *arg,
 			    int unset)
 {
-	BUG_ON_OPT_NEG(unset);
+	struct strbuf *sprefix;
-	subject_prefix = 1;
-	((struct rev_info *)opt->value)->subject_prefix = arg;
-	return 0;
-}
 
-static int rfc_callback(const struct option *opt, const char *arg, int unset)
-{
 	BUG_ON_OPT_NEG(unset);
-	BUG_ON_OPT_ARG(arg);
+	sprefix = opt->value;
-	return subject_prefix_callback(opt, "RFC PATCH", unset);
+	subject_prefix = 1;
+	strbuf_reset(sprefix);
+	strbuf_addstr(sprefix, arg);
+	return 0;
 }
 
 static int numbered_cmdline_opt = 0;
@@ -1920,6 +1917,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	struct strbuf rdiff_title = STRBUF_INIT;
 	struct strbuf sprefix = STRBUF_INIT;
 	int creation_factor = -1;
+	int rfc = 0;
 
 	const struct option builtin_format_patch_options[] = {
 		OPT_CALLBACK_F('n', "numbered", &numbered, NULL,
@@ -1943,15 +1941,13 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 			    N_("mark the series as Nth 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,
+		OPT_BOOL(0, "rfc", &rfc, N_("use [RFC PATCH] instead of [PATCH]")),
-			    N_("use [RFC PATCH] instead of [PATCH]"),
-			    PARSE_OPT_NOARG | PARSE_OPT_NONEG, rfc_callback),
 		OPT_STRING(0, "cover-from-description", &cover_from_description_arg,
 			    N_("cover-from-description-mode"),
 			    N_("generate parts of a cover letter based on a branch's description")),
 		OPT_FILENAME(0, "description-file", &description_file,
 			     N_("use branch description from file")),
-		OPT_CALLBACK_F(0, "subject-prefix", &rev, N_("prefix"),
+		OPT_CALLBACK_F(0, "subject-prefix", &sprefix, N_("prefix"),
 			    N_("use [<prefix>] instead of [PATCH]"),
 			    PARSE_OPT_NONEG, subject_prefix_callback),
 		OPT_CALLBACK_F('o', "output-directory", &output_directory,
@@ -2031,11 +2027,11 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	rev.max_parents = 1;
 	rev.diffopt.flags.recursive = 1;
 	rev.diffopt.no_free = 1;
-	rev.subject_prefix = fmt_patch_subject_prefix;
 	memset(&s_r_opt, 0, sizeof(s_r_opt));
 	s_r_opt.def = "HEAD";
 	s_r_opt.revarg_opt = REVARG_COMMITTISH;
 
+	strbuf_addstr(&sprefix, fmt_patch_subject_prefix);
 	if (format_no_prefix)
 		diff_set_noprefix(&rev.diffopt);
 
@@ -2063,13 +2059,16 @@ 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 (rfc)
+		strbuf_insertstr(&sprefix, 0, "RFC ");
+
 	if (reroll_count) {
-		strbuf_addf(&sprefix, "%s v%s",
+		strbuf_addf(&sprefix, " v%s", reroll_count);
-			    rev.subject_prefix, reroll_count);
 		rev.reroll_count = reroll_count;
-		rev.subject_prefix = sprefix.buf;
 	}
 
+	rev.subject_prefix = sprefix.buf;
+
 	for (i = 0; i < extra_hdr.nr; i++) {
 		strbuf_addstr(&buf, extra_hdr.items[i].string);
 		strbuf_addch(&buf, '\n');

t/t4014-format-patch.sh

@@ -1373,7 +1373,27 @@ test_expect_success '--rfc' '
 	Subject: [RFC PATCH 1/1] header with . in it
 	EOF
 	git format-patch -n -1 --stdout --rfc >patch &&
-	grep ^Subject: patch >actual &&
+	grep "^Subject:" patch >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--rfc does not overwrite prefix' '
+	cat >expect <<-\EOF &&
+	Subject: [RFC PATCH foobar 1/1] header with . in it
+	EOF
+	git -c format.subjectPrefix="PATCH foobar" \
+		format-patch -n -1 --stdout --rfc >patch &&
+	grep "^Subject:" patch >actual &&
+	test_cmp expect actual
+'
+
+test_expect_success '--rfc is argument order independent' '
+	cat >expect <<-\EOF &&
+	Subject: [RFC PATCH foobar 1/1] header with . in it
+	EOF
+	git format-patch -n -1 --stdout --rfc \
+		--subject-prefix="PATCH foobar" >patch &&
+	grep "^Subject:" patch >actual &&
 	test_cmp expect actual
 '