[PATCH v13 4/6] remote: add "git remote add --limited-fetch"

@@ -10,7 +10,7 @@ SYNOPSIS
 --------
 [synopsis]
 git remote [-v | --verbose]
-git remote add [-t <branch>] [-m <master>] [-f] [--[no-]tags] [--mirror=(fetch|push)] <name> <URL>
+git remote add [-t <branch>] [-m <master>] [-f] [--[no-]tags] [--mirror=(fetch|push)] [--[no-]limited-fetch] <name> <URL>
 git remote rename [--[no-]progress] <old> <new>
 git remote remove <name>
 git remote set-head <name> (-a | --auto | -d | --delete | <branch>)

@@ -75,6 +75,12 @@ the `refs/remotes/<name>/` namespace, a refspec to track only _<branch>_
 is created.  You can give more than one `-t <branch>` to track
 multiple branches without grabbing all branches.
 +
+With `--limited-fetch` option, instead of a `remote.<name>.fetch` refspec
+that tracks all branches, `remote.<name>.fetchRefmap` is set up so that a
+refspec-less `git fetch <name>` only fetches branches our local branches
+are built on. See the `--refmap` entry in linkgit:git-fetch[1] for
+details.
++
 With `-m <master>` option, a symbolic-ref `refs/remotes/<name>/HEAD` is set
 up to point at remote's _<master>_ branch. See also the set-head command.
 +

@@ -179,6 +179,7 @@ static int add(int argc, const char **argv, const char *prefix,
 {
 	int fetch = 0, fetch_tags = TAGS_DEFAULT;
 	unsigned mirror = MIRROR_NONE;
+	int limited_fetch = -1; /* unspecified */
 	struct string_list track = STRING_LIST_INIT_NODUP;
 	const char *master = NULL;
 	struct remote *remote;

@@ -198,6 +199,8 @@ static int add(int argc, const char **argv, const char *prefix,
 		OPT_CALLBACK_F(0, "mirror", &mirror, "(push|fetch)",
 			N_("set up remote as a mirror to push to or fetch from"),
 			PARSE_OPT_OPTARG | PARSE_OPT_COMP_ARG, parse_mirror_opt),
+		OPT_BOOL(0, "limited-fetch", &limited_fetch,
+			N_("fetch only the branches we build on, instead of every branch")),
 		OPT_END()
 	};
 

@@ -211,6 +214,10 @@ static int add(int argc, const char **argv, const char *prefix,
 		die(_("specifying a master branch makes no sense with --mirror"));
 	if (mirror && !(mirror & MIRROR_FETCH) && track.nr)
 		die(_("specifying branches to track makes sense only with fetch mirrors"));
+	if (limited_fetch == 1 && track.nr)
+		die(_("--limited-fetch does not make sense with -t/--track"));
+	if (limited_fetch == 1 && mirror)
+		die(_("--limited-fetch does not make sense with --mirror"));
 
 	name = argv[0];
 	url = argv[1];

@@ -230,13 +237,22 @@ static int add(int argc, const char **argv, const char *prefix,
 	repo_config_set(the_repository, buf.buf, url);
 
 	if (!mirror || mirror & MIRROR_FETCH) {
+		bool use_limited_fetch = mirror == MIRROR_NONE && track.nr == 0 &&
+			limited_fetch == 1;
+
 		strbuf_reset(&buf);
-		strbuf_addf(&buf, "remote.%s.fetch", name);
-		if (track.nr == 0)
-			string_list_append(&track, "*");
-		for (size_t i = 0; i < track.nr; i++) {
-			add_branch(buf.buf, track.items[i].string,
-				   name, mirror, &buf2);
+		if (use_limited_fetch) {
+			strbuf_addf(&buf, "remote.%s.fetchRefmap", name);
+			strbuf_reset(&buf2);
+			strbuf_addf(&buf2, "+refs/heads/*:refs/remotes/%s/*", name);
+			repo_config_set(the_repository, buf.buf, buf2.buf);
+		} else {
+			strbuf_addf(&buf, "remote.%s.fetch", name);
+			if (track.nr == 0)
+				string_list_append(&track, "*");
+			for (size_t i = 0; i < track.nr; i++)
+				add_branch(buf.buf, track.items[i].string,
+					   name, mirror, &buf2);
 		}
 	}
 

@@ -137,6 +137,22 @@ test_expect_success 'filters are listed by git remote -v only' '
 	test_grep ! "\[blob:none\]" out
 '
 
+test_expect_success '--limited-fetch works in a full repository too' '
+	test_when_finished "rm -rf full-add" &&
+	git clone --no-local one full-add &&
+	(
+		cd full-add &&
+		git remote add --limited-fetch upstream ../two &&
+		test_cmp_config "+refs/heads/*:refs/remotes/upstream/*" \
+			remote.upstream.fetchRefmap &&
+		test_must_fail git config get remote.upstream.fetch
+	)
+'
+
+test_expect_success '--limited-fetch conflicts with -t' '
+	test_must_fail git remote add --limited-fetch -t main upstream ../two
+'
+
 test_expect_success 'check remote-tracking' '
 	(
 		cd test &&