submodule sync: do not auto-vivify uninteresting submodule

Earlier 33f072f (submodule sync: Update "submodule.<name>.url" for empty
directories, 2010-10-08) attempted to fix a bug where "git submodule sync"
command does not update the URL if the current superproject does not have
a checkout of the submodule.

However, it did so by unconditionally registering submodule.$name.url to
every submodule in the project, even the ones that the user has never
showed interest in at all by running 'git submodule init' command. This
caused subsequent 'git submodule update' to start cloning/updating submodules
that are not interesting to the user at all.

Update the code so that the URL is updated from the .gitmodules file only
for submodules that already have submodule.$name.url entries, i.e. the
ones the user has showed interested in having a checkout.

Acked-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

3 files changed, 29 insertions, 13 deletions

diff --git a/Documentation/git-submodule.txt b/Documentation/git-submodule.txt
index 1ed331c599..710633f965 100644
--- a/Documentation/git-submodule.txt
+++ b/Documentation/git-submodule.txt
@@ -166,7 +166,9 @@ commit for each submodule.
 
 sync::
 	Synchronizes submodules' remote URL configuration setting
-	to the value specified in .gitmodules.  This is useful when
+	to the value specified in .gitmodules. It will only affect those
+	submodules which already have an url entry in .git/config (that is the
+	case when they are initialized or freshly added). This is useful when
 	submodule URLs change upstream and you need to update your local
 	repositories accordingly.
 +
diff --git a/git-submodule.sh b/git-submodule.sh
index c291eed59c..ce659714fe 100755
--- a/git-submodule.sh
+++ b/git-submodule.sh
@@ -836,17 +836,20 @@ cmd_sync()
 			;;
 		esac
 
-		say "Synchronizing submodule url for '$name'"
-		git config submodule."$name".url "$url"
-
-		if test -e "$path"/.git
+		if git config "submodule.$name.url" >/dev/null 2>/dev/null
 		then
-		(
-			clear_local_git_env
-			cd "$path"
-			remote=$(get_default_remote)
-			git config remote."$remote".url "$url"
-		)
+			say "Synchronizing submodule url for '$name'"
+			git config submodule."$name".url "$url"
+
+			if test -e "$path"/.git
+			then
+			(
+				clear_local_git_env
+				cd "$path"
+				remote=$(get_default_remote)
+				git config remote."$remote".url "$url"
+			)
+			fi
 		fi
 	done
 }
diff --git a/t/t7403-submodule-sync.sh b/t/t7403-submodule-sync.sh
index e5b19538b0..fb21b87683 100755
--- a/t/t7403-submodule-sync.sh
+++ b/t/t7403-submodule-sync.sh
@@ -25,7 +25,8 @@ test_expect_success setup '
 	git clone super super-clone &&
 	(cd super-clone && git submodule update --init) &&
 	git clone super empty-clone &&
-	(cd empty-clone && git submodule init)
+	(cd empty-clone && git submodule init) &&
+	git clone super top-only-clone
 '
 
 test_expect_success 'change submodule' '
@@ -66,7 +67,7 @@ test_expect_success '"git submodule sync" should update submodule URLs' '
 	)
 '
 
-test_expect_success '"git submodule sync" should update submodule URLs if not yet cloned' '
+test_expect_success '"git submodule sync" should update known submodule URLs' '
 	(cd empty-clone &&
 	 git pull &&
 	 git submodule sync &&
@@ -74,4 +75,14 @@ test_expect_success '"git submodule sync" should update submodule URLs if not ye
 	)
 '
 
+test_expect_success '"git submodule sync" should not vivify uninteresting submodule' '
+	(cd top-only-clone &&
+	 git pull &&
+	 git submodule sync &&
+	 test -z "$(git config submodule.submodule.url)" &&
+	 git submodule sync submodule &&
+	 test -z "$(git config submodule.submodule.url)"
+	)
+'
+
 test_done