git clone: Add --recursive to automatically checkout (nested) submodules

Many projects using submodules expect all submodules to be checked out
in order to build/work correctly. A common command sequence for
developers on such projects is:

	git clone url/to/project
	cd project
	git submodule update --init (--recursive)

This patch introduces the --recursive option to git-clone. The new
option causes git-clone to recursively clone and checkout all
submodules of the cloned project. Hence, the above command sequence
can be reduced to:

	git clone --recursive url/to/project

--recursive is ignored if no checkout is done by the git-clone.

The patch also includes documentation and a selftest.

Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-clone.txt

@@ -12,7 +12,7 @@ SYNOPSIS
 'git clone' [--template=<template_directory>]
 	  [-l] [-s] [--no-hardlinks] [-q] [-n] [--bare] [--mirror]
 	  [-o <name>] [-u <upload-pack>] [--reference <repository>]
-	  [--depth <depth>] [--] <repository> [<directory>]
+	  [--depth <depth>] [--recursive] [--] <repository> [<directory>]
 
 DESCRIPTION
 -----------
@@ -139,6 +139,14 @@ then the cloned repository will become corrupt.
 	with a long history, and would want to send in fixes
 	as patches.
 
+--recursive::
+	After the clone is created, initialize all submodules within,
+	using their default settings. This is equivalent to running
+	'git submodule update --init --recursive' immediately after
+	the clone is finished. This option is ignored if the cloned
+	repository does not have a worktree/checkout (i.e. if any of
+	`--no-checkout`/`-n`, `--bare`, or `--mirror` is given)
+
 <repository>::
 	The (possibly remote) repository to clone from.  See the
 	<<URLS,URLS>> section below for more information on specifying

builtin-clone.c

@@ -38,7 +38,7 @@ static const char * const builtin_clone_usage[] = {
 };
 
 static int option_quiet, option_no_checkout, option_bare, option_mirror;
-static int option_local, option_no_hardlinks, option_shared;
+static int option_local, option_no_hardlinks, option_shared, option_recursive;
 static char *option_template, *option_reference, *option_depth;
 static char *option_origin = NULL;
 static char *option_upload_pack = "git-upload-pack";
@@ -59,6 +59,8 @@ static struct option builtin_clone_options[] = {
 		    "don't use local hardlinks, always copy"),
 	OPT_BOOLEAN('s', "shared", &option_shared,
 		    "setup as shared repository"),
+	OPT_BOOLEAN(0, "recursive", &option_recursive,
+		    "setup as shared repository"),
 	OPT_STRING(0, "template", &option_template, "path",
 		   "path the template repository"),
 	OPT_STRING(0, "reference", &option_reference, "repo",
@@ -73,6 +75,10 @@ static struct option builtin_clone_options[] = {
 	OPT_END()
 };
 
+static const char *argv_submodule[] = {
+	"submodule", "update", "--init", "--recursive", NULL
+};
+
 static char *get_repo_path(const char *repo, int *is_bundle)
 {
 	static char *suffix[] = { "/.git", ".git", "" };
@@ -608,6 +614,9 @@ int cmd_clone(int argc, const char **argv, const char *prefix)
 
 		err |= run_hook(NULL, "post-checkout", sha1_to_hex(null_sha1),
 				sha1_to_hex(remote_head->old_sha1), "1", NULL);
+
+		if (!err && option_recursive)
+			err = run_command_v_opt(argv_submodule, RUN_GIT_CMD);
 	}
 
 	strbuf_release(&reflog_msg);

t/t7407-submodule-foreach.sh

@@ -222,4 +222,16 @@ test_expect_success 'test "status --recursive"' '
 	test_cmp expect actual
 '
 
+test_expect_success 'use "git clone --recursive" to checkout all submodules' '
+	git clone --recursive super clone4 &&
+	test -d clone4/.git &&
+	test -d clone4/sub1/.git &&
+	test -d clone4/sub2/.git &&
+	test -d clone4/sub3/.git &&
+	test -d clone4/nested1/.git &&
+	test -d clone4/nested1/nested2/.git &&
+	test -d clone4/nested1/nested2/nested3/.git &&
+	test -d clone4/nested1/nested2/nested3/submodule/.git
+'
+
 test_done