remote: add --set-head option to 'git remote add'

Mirror the behavior 'git clone' applies to its first remote: after
fetching, set refs/remotes/<name>/HEAD to the remote's default branch.

Equivalent to running:

    git remote add -f <name> <url>
    git remote set-head <name> -a

The new option implies --fetch.

Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>

Author: HaraldNordgren

Documentation/git-remote.adoc

@@ -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] [--set-head] [--[no-]tags] [--mirror=(fetch|push)] <name> <URL>
 git remote rename [--[no-]progress] <old> <new>
 git remote remove <name>
 git remote set-head <name> (-a | --auto | -d | --delete | <branch>)
@@ -73,6 +73,13 @@ multiple branches without grabbing all branches.
 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.
 +
+With `--set-head` option, a symbolic-ref `refs/remotes/<name>/HEAD` is set
+up to point at the remote's default branch, mirroring the behavior of
+`git clone`. This is equivalent to running `git remote set-head <name> -a`
+after the remote is added, and implies `-f` so that the remote's refs are
+available locally. It cannot be combined with `-m <master>` or with a push
+mirror.
++
 When a fetch mirror is created with `--mirror=fetch`, the refs will not
 be stored in the `refs/remotes/` namespace, but rather everything in
 `refs/` on the remote will be directly mirrored into `refs/` in the

builtin/remote.c

@@ -23,7 +23,7 @@
 
 static const char * const builtin_remote_usage[] = {
 	"git remote [-v | --verbose]",
-	N_("git remote add [-t <branch>] [-m <master>] [-f] [--tags | --no-tags] [--mirror=<fetch|push>] <name> <url>"),
+	N_("git remote add [-t <branch>] [-m <master>] [-f] [--set-head] [--tags | --no-tags] [--mirror=<fetch|push>] <name> <url>"),
 	N_("git remote rename [--[no-]progress] <old> <new>"),
 	N_("git remote remove <name>"),
 	N_("git remote set-head <name> (-a | --auto | -d | --delete | <branch>)"),
@@ -174,10 +174,21 @@ static int check_remote_collision(struct remote *remote, void *data)
 	return 0;
 }
 
+static int set_head_auto_for_remote(const char *name)
+{
+	struct child_process cmd = CHILD_PROCESS_INIT;
+
+	strvec_pushl(&cmd.args, "remote", "set-head", "--auto", name, NULL);
+	cmd.git_cmd = 1;
+	if (run_command(&cmd))
+		return error(_("Could not set up HEAD for %s"), name);
+	return 0;
+}
+
 static int add(int argc, const char **argv, const char *prefix,
 	       struct repository *repo UNUSED)
 {
-	int fetch = 0, fetch_tags = TAGS_DEFAULT;
+	int fetch = 0, fetch_tags = TAGS_DEFAULT, set_head_auto = 0;
 	unsigned mirror = MIRROR_NONE;
 	struct string_list track = STRING_LIST_INIT_NODUP;
 	const char *master = NULL;
@@ -195,6 +206,8 @@ static int add(int argc, const char **argv, const char *prefix,
 		OPT_STRING_LIST('t', "track", &track, N_("branch"),
 				N_("branch(es) to track")),
 		OPT_STRING('m', "master", &master, N_("branch"), N_("master branch")),
+		OPT_BOOL(0, "set-head", &set_head_auto,
+			 N_("set refs/remotes/<name>/HEAD according to remote (implies --fetch)")),
 		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),
@@ -211,6 +224,12 @@ 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 (set_head_auto && master)
+		die(_("--set-head and --master are mutually exclusive"));
+	if (set_head_auto && mirror && !(mirror & MIRROR_FETCH))
+		die(_("--set-head makes no sense with a push mirror"));
+	if (set_head_auto)
+		fetch = 1;
 
 	name = argv[0];
 	url = argv[1];
@@ -269,6 +288,9 @@ static int add(int argc, const char **argv, const char *prefix,
 			result = error(_("Could not setup master '%s'"), master);
 	}
 
+	if (set_head_auto && set_head_auto_for_remote(name))
+		result = 1;
+
 out:
 	strbuf_release(&buf);
 	strbuf_release(&buf2);

t/t5505-remote.sh

@@ -81,6 +81,14 @@ test_expect_success 'add another remote' '
 	)
 '
 
+test_expect_success 'add remote with --set-head implies --fetch and sets HEAD' '
+	test_when_finished "git -C test remote remove third" &&
+	git -C test remote add --set-head third ../two &&
+	echo refs/remotes/third/main >expect &&
+	git -C test symbolic-ref refs/remotes/third/HEAD >actual &&
+	test_cmp expect actual
+'
+
 test_expect_success 'setup bare clone for server' '
 	git clone --bare "file://$(pwd)/one" srv.bare &&
 	git -C srv.bare config --local uploadpack.allowfilter 1 &&