[PATCH 5/6] worktree move: refuse to move worktrees with submodules

["Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>]

Submodules contains .git files with relative paths. After a worktree
move, these files need to be updated or they may point to nowhere.

This is a bandage patch to make sure "worktree move" don't break
people's worktrees by accident. When .git file update code is in
place, this validate_no_submodules() could be removed.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
---
 builtin/worktree.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/builtin/worktree.c b/builtin/worktree.c
index 116507e47e..825b3e9d9a 100644
--- a/builtin/worktree.c
+++ b/builtin/worktree.c
@@ -526,6 +526,27 @@ static int unlock_worktree(int ac, const char **av, const char *prefix)
 	return ret;
 }
 
+static void validate_no_submodules(const struct worktree *wt)
+{
+	struct index_state istate = {0};
+	int i, found_submodules = 0;
+
+	if (read_index_from(&istate, worktree_git_path(wt, "index")) > 0) {
+		for (i = 0; i < istate.cache_nr; i++) {
+			struct cache_entry *ce = istate.cache[i];
+
+			if (S_ISGITLINK(ce->ce_mode)) {
+				found_submodules = 1;
+				break;
+			}
+		}
+	}
+	discard_index(&istate);
+
+	if (found_submodules)
+		die(_("This working tree contains submodules and cannot be moved yet"));
+}
+
 static int move_worktree(int ac, const char **av, const char *prefix)
 {
 	struct option options[] = {
@@ -564,6 +585,8 @@ static int move_worktree(int ac, const char **av, const char *prefix)
 	if (validate_worktree(wt, 0))
 		return -1;
 
+	validate_no_submodules(wt);
+
 	if (is_directory(dst.buf)) {
 		const char *sep = find_last_dir_sep(wt->path);
 
-- 
2.11.0.157.gd943d85