From: Junio C Hamano <gitster@pobox.com>
Date: Wed, 6 Dec 2017 17:23:35 +0000 (-0800)
Subject: Merge branch 'sb/submodule-recursive-checkout-detach-head'
X-Git-Tag: v2.16.0-rc0~84
X-Git-Url: https://git.lorimer.id.au/gitweb.git/diff_plain/0b75572a1b9f601b751d431faea55f492ea92ac9?hp=1a4e40aa5dc16564af879142ba9dfbbb88d1e5ff

Merge branch 'sb/submodule-recursive-checkout-detach-head'

"git checkout --recursive" may overwrite and rewind the history of
the branch that happens to be checked out in submodule
repositories, which might not be desirable.  Detach the HEAD but
still allow the recursive checkout to succeed in such a case.

* sb/submodule-recursive-checkout-detach-head:
Documentation/checkout: clarify submodule HEADs to be detached
recursive submodules: detach HEAD from new state
---

diff --git a/Documentation/git-checkout.txt b/Documentation/git-checkout.txt
index e108b0f74b..bfa64ca5c9 100644
--- a/Documentation/git-checkout.txt
+++ b/Documentation/git-checkout.txt
@@ -264,6 +264,8 @@ section of linkgit:git-add[1] to learn how to operate the `--patch` mode.
 	local modifications in a submodule would be overwritten the checkout
 	will fail unless `-f` is used. If nothing (or --no-recurse-submodules)
 	is used, the work trees of submodules will not be updated.
+	Just like linkgit:git-submodule[1], this will detach the
+	submodules HEAD.
 
 <branch>::
 	Branch to checkout; if it refers to a branch (i.e., a name that,
diff --git a/submodule.c b/submodule.c
index bb531e0e59..95e6aff2bb 100644
--- a/submodule.c
+++ b/submodule.c
@@ -1670,7 +1670,8 @@ int submodule_move_head(const char *path,
 			cp.dir = path;
 
 			prepare_submodule_repo_env(&cp.env_array);
-			argv_array_pushl(&cp.args, "update-ref", "HEAD", new, NULL);
+			argv_array_pushl(&cp.args, "update-ref", "HEAD",
+					 "--no-deref", new, NULL);
 
 			if (run_command(&cp)) {
 				ret = -1;
diff --git a/t/lib-submodule-update.sh b/t/lib-submodule-update.sh
index bb94c23209..9058bf978a 100755
--- a/t/lib-submodule-update.sh
+++ b/t/lib-submodule-update.sh
@@ -689,6 +689,23 @@ test_submodule_switch_recursing_with_args () {
 			test_submodule_content sub1 origin/add_sub1
 		)
 	'
+	test_expect_success "$command: submodule branch is not changed, detach HEAD instead" '
+		prolog &&
+		reset_work_tree_to_interested add_sub1 &&
+		(
+			cd submodule_update &&
+			git -C sub1 checkout -b keep_branch &&
+			git -C sub1 rev-parse HEAD >expect &&
+			git branch -t check-keep origin/modify_sub1 &&
+			$command check-keep &&
+			test_superproject_content origin/modify_sub1 &&
+			test_submodule_content sub1 origin/modify_sub1 &&
+			git -C sub1 rev-parse keep_branch >actual &&
+			test_cmp expect actual &&
+			test_must_fail git -C sub1 symbolic-ref HEAD
+		)
+	'
+
 	# Replacing a tracked file with a submodule produces a checked out submodule
 	test_expect_success "$command: replace tracked file with submodule checks out submodule" '
 		prolog &&