stash: convert branch to builtin

Add stash branch to the helper and delete the apply_to_branch
function from the shell script.

Checkout does not currently provide a function for checking out
a branch as cmd_checkout does a large amount of sanity checks
first that we require here.

Signed-off-by: Joel Teichroeb <joel@teichroeb.net>
Signed-off-by: Paul-Sebastian Ungureanu <ungureanupaulsebastian@gmail.com>
Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/stash--helper.c

@@ -14,6 +14,7 @@
 static const char * const git_stash_helper_usage[] = {
 	N_("git stash--helper drop [-q|--quiet] [<stash>]"),
 	N_("git stash--helper apply [--index] [-q|--quiet] [<stash>]"),
+	N_("git stash--helper branch <branchname> [<stash>]"),
 	N_("git stash--helper clear"),
 	NULL
 };
@@ -28,6 +29,11 @@ static const char * const git_stash_helper_apply_usage[] = {
 	NULL
 };
 
+static const char * const git_stash_helper_branch_usage[] = {
+	N_("git stash--helper branch <branchname> [<stash>]"),
+	NULL
+};
+
 static const char * const git_stash_helper_clear_usage[] = {
 	N_("git stash--helper clear"),
 	NULL
@@ -536,6 +542,44 @@ static int drop_stash(int argc, const char **argv, const char *prefix)
 	return ret;
 }
 
+static int branch_stash(int argc, const char **argv, const char *prefix)
+{
+	int ret;
+	const char *branch = NULL;
+	struct stash_info info;
+	struct child_process cp = CHILD_PROCESS_INIT;
+	struct option options[] = {
+		OPT_END()
+	};
+
+	argc = parse_options(argc, argv, prefix, options,
+			     git_stash_helper_branch_usage, 0);
+
+	if (!argc) {
+		fprintf_ln(stderr, _("No branch name specified"));
+		return -1;
+	}
+
+	branch = argv[0];
+
+	if (get_stash_info(&info, argc - 1, argv + 1))
+		return -1;
+
+	cp.git_cmd = 1;
+	argv_array_pushl(&cp.args, "checkout", "-b", NULL);
+	argv_array_push(&cp.args, branch);
+	argv_array_push(&cp.args, oid_to_hex(&info.b_commit));
+	ret = run_command(&cp);
+	if (!ret)
+		ret = do_apply_stash(prefix, &info, 1, 0);
+	if (!ret && info.is_stash_ref)
+		ret = do_drop_stash(prefix, &info, 0);
+
+	free_stash_info(&info);
+
+	return ret;
+}
+
 int cmd_stash__helper(int argc, const char **argv, const char *prefix)
 {
 	pid_t pid = getpid();
@@ -562,6 +606,8 @@ int cmd_stash__helper(int argc, const char **argv, const char *prefix)
 		return !!clear_stash(argc, argv, prefix);
 	else if (!strcmp(argv[0], "drop"))
 		return !!drop_stash(argc, argv, prefix);
+	else if (!strcmp(argv[0], "branch"))
+		return !!branch_stash(argc, argv, prefix);
 
 	usage_msg_opt(xstrfmt(_("unknown subcommand: %s"), argv[0]),
 		      git_stash_helper_usage, options);

git-stash.sh

@@ -615,20 +615,6 @@ drop_stash () {
 	clear_stash
 }
 
-apply_to_branch () {
-	test -n "$1" || die "$(gettext "No branch name specified")"
-	branch=$1
-	shift 1
-
-	set -- --index "$@"
-	assert_stash_like "$@"
-
-	git checkout -b $branch $REV^ &&
-	apply_stash "$@" && {
-		test -z "$IS_STASH_REF" || drop_stash "$@"
-	}
-}
-
 test "$1" = "-p" && set "push" "$@"
 
 PARSE_CACHE='--not-parsed'
@@ -690,7 +676,8 @@ pop)
 	;;
 branch)
 	shift
-	apply_to_branch "$@"
+	cd "$START_DIR"
+	git stash--helper branch "$@"
 	;;
 *)
 	case $# in