Teach "git submodule add" the --name option

"git submodule add" initializes the name of a submodule to its path. This
was ok as long as the .git directory lived inside the submodule's work
tree, but since 1.7.8 it is stored in the .git/modules/<name> directory of
the superproject, making the submodule name survive the removal of the
submodule's work tree. This leads to problems when the user tries to add a
different submodule at the same path - and thus the same name - later, as
that will happily try to restore the submodule from the old repository
instead of the one the user specified and will lead to a checkout of the
wrong repository.

Add the new "--name" option to let the user provide a name for the
submodule. This enables the user to solve this conflict without having to
remove .git/modules/<name> by hand (which is no viable solution as it
makes it impossible to checkout a commit that records the old submodule
and populate it, as that will still check out the new submodule for the
same reason).

To achieve that the submodule's name is added to the parameter list of
the module_clone() helper function. This makes it possible to remove the
call of module_name() there because both callers of module_clone() already
know the name and can provide it as argument number two.

Reported-by: Jonathan Johnson <me@jondavidjohn.com>
Signed-off-by: Jens Lehmann <Jens.Lehmann@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-submodule.txt

@@ -9,7 +9,7 @@ git-submodule - Initialize, update or inspect submodules
 SYNOPSIS
 --------
 [verse]
-'git submodule' [--quiet] add [-b branch] [-f|--force]
+'git submodule' [--quiet] add [-b branch] [-f|--force] [--name <name>]
 	      [--reference <repository>] [--] <repository> [<path>]
 'git submodule' [--quiet] status [--cached] [--recursive] [--] [<path>...]
 'git submodule' [--quiet] init [--] [<path>...]
@@ -266,6 +266,11 @@ OPTIONS
 	Initialize all submodules for which "git submodule init" has not been
 	called so far before updating.
 
+--name::
+	This option is only valid for the add command. It sets the submodule's
+	name to the given string instead of defaulting to its path. The name
+	must be valid as a directory name and may not end with a '/'.
+
 --reference <repository>::
 	This option is only valid for add and update commands.  These
 	commands sometimes need to clone a remote repository. In this case,

Documentation/gitmodules.txt

@@ -18,7 +18,9 @@ working tree, is a text file with a syntax matching the requirements
 of linkgit:git-config[1].
 
 The file contains one subsection per submodule, and the subsection value
-is the name of the submodule. Each submodule section also contains the
+is the name of the submodule. The name is set to the path where the
+submodule has been added unless it was customized with the '--name'
+option of 'git submodule add'. Each submodule section also contains the
 following required keys:
 
 submodule.<name>.path::

git-submodule.sh

@@ -5,7 +5,7 @@
 # Copyright (c) 2007 Lars Hjemli
 
 dashless=$(basename "$0" | sed -e 's/-/ /')
-USAGE="[--quiet] add [-b branch] [-f|--force] [--reference <repository>] [--] <repository> [<path>]
+USAGE="[--quiet] add [-b branch] [-f|--force] [--name <name>] [--reference <repository>] [--] <repository> [<path>]
    or: $dashless [--quiet] status [--cached] [--recursive] [--] [<path>...]
    or: $dashless [--quiet] init [--] [<path>...]
    or: $dashless [--quiet] update [--init] [-N|--no-fetch] [-f|--force] [--rebase] [--reference <repository>] [--merge] [--recursive] [--] [<path>...]
@@ -29,6 +29,7 @@ files=
 nofetch=
 update=
 prefix=
+custom_name=
 
 # The function takes at most 2 arguments. The first argument is the
 # URL that navigates to the submodule origin repo. When relative, this URL
@@ -179,8 +180,9 @@ module_name()
 module_clone()
 {
 	sm_path=$1
-	url=$2
-	reference="$3"
+	name=$2
+	url=$3
+	reference="$4"
 	quiet=
 	if test -n "$GIT_QUIET"
 	then
@@ -189,8 +191,6 @@ module_clone()
 
 	gitdir=
 	gitdir_base=
-	name=$(module_name "$sm_path" 2>/dev/null)
-	test -n "$name" || name="$sm_path"
 	base_name=$(dirname "$name")
 
 	gitdir=$(git rev-parse --git-dir)
@@ -272,6 +272,11 @@ cmd_add()
 			reference="$1"
 			shift
 			;;
+		--name)
+			case "$2" in '') usage ;; esac
+			custom_name=$2
+			shift
+			;;
 		--)
 			shift
 			break
@@ -336,6 +341,13 @@ Use -f if you really want to add it." >&2
 		exit 1
 	fi
 
+	if test -n "$custom_name"
+	then
+		sm_name="$custom_name"
+	else
+		sm_name="$sm_path"
+	fi
+
 	# perhaps the path exists and is already a git repo, else clone it
 	if test -e "$sm_path"
 	then
@@ -348,7 +360,7 @@ Use -f if you really want to add it." >&2
 
 	else
 
-		module_clone "$sm_path" "$realrepo" "$reference" || exit
+		module_clone "$sm_path" "$sm_name" "$realrepo" "$reference" || exit
 		(
 			clear_local_git_env
 			cd "$sm_path" &&
@@ -359,13 +371,13 @@ Use -f if you really want to add it." >&2
 			esac
 		) || die "$(eval_gettext "Unable to checkout submodule '\$sm_path'")"
 	fi
-	git config submodule."$sm_path".url "$realrepo"
+	git config submodule."$sm_name".url "$realrepo"
 
 	git add $force "$sm_path" ||
 	die "$(eval_gettext "Failed to add submodule '\$sm_path'")"
 
-	git config -f .gitmodules submodule."$sm_path".path "$sm_path" &&
-	git config -f .gitmodules submodule."$sm_path".url "$repo" &&
+	git config -f .gitmodules submodule."$sm_name".path "$sm_path" &&
+	git config -f .gitmodules submodule."$sm_name".url "$repo" &&
 	git add --force .gitmodules ||
 	die "$(eval_gettext "Failed to register submodule '\$sm_path'")"
 }
@@ -594,7 +606,7 @@ Maybe you want to use 'update --init'?")"
 
 		if ! test -d "$sm_path"/.git -o -f "$sm_path"/.git
 		then
-			module_clone "$sm_path" "$url" "$reference"|| exit
+			module_clone "$sm_path" "$name" "$url" "$reference" || exit
 			cloned_modules="$cloned_modules;$name"
 			subsha1=
 		else

t/t7400-submodule-basic.sh

@@ -681,4 +681,49 @@ test_expect_success 'moving the superproject does not break submodules' '
 	)
 '
 
+test_expect_success 'submodule add --name allows to replace a submodule with another at the same path' '
+	(
+		cd addtest2 &&
+		(
+			cd repo &&
+			echo "$submodurl/repo" >expect &&
+			git config remote.origin.url >actual &&
+			test_cmp expect actual &&
+			echo "gitdir: ../.git/modules/repo" >expect &&
+			test_cmp expect .git
+		) &&
+		rm -rf repo &&
+		git rm repo &&
+		git submodule add -q --name repo_new "$submodurl/bare.git" repo >actual &&
+		test ! -s actual &&
+		echo "gitdir: ../.git/modules/submod" >expect &&
+		test_cmp expect submod/.git &&
+		(
+			cd repo &&
+			echo "$submodurl/bare.git" >expect &&
+			git config remote.origin.url >actual &&
+			test_cmp expect actual &&
+			echo "gitdir: ../.git/modules/repo_new" >expect &&
+			test_cmp expect .git
+		) &&
+		echo "repo" >expect &&
+		git config -f .gitmodules submodule.repo.path >actual &&
+		test_cmp expect actual &&
+		git config -f .gitmodules submodule.repo_new.path >actual &&
+		test_cmp expect actual&&
+		echo "$submodurl/repo" >expect &&
+		git config -f .gitmodules submodule.repo.url >actual &&
+		test_cmp expect actual &&
+		echo "$submodurl/bare.git" >expect &&
+		git config -f .gitmodules submodule.repo_new.url >actual &&
+		test_cmp expect actual &&
+		echo "$submodurl/repo" >expect &&
+		git config submodule.repo.url >actual &&
+		test_cmp expect actual &&
+		echo "$submodurl/bare.git" >expect &&
+		git config submodule.repo_new.url >actual &&
+		test_cmp expect actual
+	)
+'
+
 test_done