[PATCH v2 1/7] clone: teach --detach option

From

Glen Choo via GitGitGadget <gitgitgadget@gmail.com>

Date

Oct 20, 2022, 20:20 UTC

Message-ID

<432bc7cb3a42cf39d0033701c2cc677c9109b3dd.1666297239.git.gitgitgadget@gmail.com>

In-Reply-To

<pull.1321.v2.git.git.1666297238.gitgitgadget@gmail.com>

From: Glen Choo <chooglen@google.com>

Signed-off-by: Glen Choo <chooglen@google.com>
---
 Documentation/git-clone.txt |  8 +++++++-
 builtin/clone.c             | 12 +++++++++---
 t/t5601-clone.sh            | 22 ++++++++++++++++++++++
 3 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/Documentation/git-clone.txt b/Documentation/git-clone.txt
index d6434d262d6..6a4e5d31b46 100644
--- a/Documentation/git-clone.txt
+++ b/Documentation/git-clone.txt
@@ -16,7 +16,7 @@ SYNOPSIS
 	  [--depth <depth>] [--[no-]single-branch] [--no-tags]
 	  [--recurse-submodules[=<pathspec>]] [--[no-]shallow-submodules]
 	  [--[no-]remote-submodules] [--jobs <n>] [--sparse] [--[no-]reject-shallow]
-	  [--filter=<filter> [--also-filter-submodules]] [--] <repository>
+	  [--filter=<filter> [--also-filter-submodules] [--detach]] [--] <repository>
 	  [<directory>]
 
 DESCRIPTION
@@ -210,6 +210,12 @@ objects from the source repository into a pack in the cloned repository.
 	`--branch` can also take tags and detaches the HEAD at that commit
 	in the resulting repository.
 
+--detach::
+	If the cloned repository's HEAD points to a branch, point the newly
+	created HEAD to the branch's commit instead of the branch itself.
+	Additionally, in a non-bare repository, the corresponding local branch
+	will not be created.
+
 -u <upload-pack>::
 --upload-pack <upload-pack>::
 	When given, and the repository to clone from is accessed
diff --git a/builtin/clone.c b/builtin/clone.c
index 547d6464b3c..e624d3f49a2 100644
--- a/builtin/clone.c
+++ b/builtin/clone.c
@@ -78,6 +78,7 @@ static int option_filter_submodules = -1;    /* unspecified */
 static int config_filter_submodules = -1;    /* unspecified */
 static struct string_list server_options = STRING_LIST_INIT_NODUP;
 static int option_remote_submodules;
+static int option_detach;
 static const char *bundle_uri;
 
 static int recurse_submodules_cb(const struct option *opt,
@@ -162,6 +163,8 @@ static struct option builtin_clone_options[] = {
 		    N_("any cloned submodules will use their remote-tracking branch")),
 	OPT_BOOL(0, "sparse", &option_sparse_checkout,
 		    N_("initialize sparse-checkout file to include only files at root")),
+	OPT_BOOL(0, "detach", &option_detach,
+		 N_("detach HEAD and don't create a local branch")),
 	OPT_STRING(0, "bundle-uri", &bundle_uri,
 		   N_("uri"), N_("a URI for downloading bundles before fetching from origin remote")),
 	OPT_END()
@@ -613,10 +616,12 @@ static void update_remote_refs(const struct ref *refs,
 }
 
 static void update_head(const struct ref *our, const struct ref *remote,
-			const char *unborn, const char *msg)
+			const char *unborn, int should_detach,
+			const char *msg)
 {
 	const char *head;
-	if (our && skip_prefix(our->name, "refs/heads/", &head)) {
+	if (our && !should_detach &&
+	    skip_prefix(our->name, "refs/heads/", &head)) {
 		/* Local default branch link */
 		if (create_symref("HEAD", our->name, NULL) < 0)
 			die(_("unable to update HEAD"));
@@ -1357,7 +1362,8 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 			   branch_top.buf, reflog_msg.buf, transport,
 			   !is_local);
 
-	update_head(our_head_points_at, remote_head, unborn_head, reflog_msg.buf);
+	update_head(our_head_points_at, remote_head, unborn_head,
+		    option_detach, reflog_msg.buf);
 
 	/*
 	 * We want to show progress for recursive submodule clones iff
diff --git a/t/t5601-clone.sh b/t/t5601-clone.sh
index 45f0803ed4d..418cfd54717 100755
--- a/t/t5601-clone.sh
+++ b/t/t5601-clone.sh
@@ -333,6 +333,28 @@ test_expect_success 'clone checking out a tag' '
 	test_cmp fetch.expected fetch.actual
 '
 
+test_expect_success '--detach detaches and does not create branch' '
+	test_when_finished "rm -fr dst" &&
+	git clone --detach src dst &&
+	(
+		cd dst &&
+		test_must_fail git rev-parse main &&
+		test_must_fail git symbolic-ref HEAD &&
+		test_cmp_rev HEAD refs/remotes/origin/HEAD
+	)
+'
+
+test_expect_success '--detach with --bare detaches but creates branch' '
+	test_when_finished "rm -fr dst" &&
+	git clone --bare --detach src dst &&
+	(
+		cd dst &&
+		git rev-parse main &&
+		test_must_fail git symbolic-ref HEAD &&
+		test_cmp_rev HEAD refs/heads/main
+	)
+'
+
 test_expect_success 'set up ssh wrapper' '
 	cp "$GIT_BUILD_DIR/t/helper/test-fake-ssh$X" \
 		"$TRASH_DIRECTORY/ssh$X" &&

-- 
gitgitgadget