[RFC PATCH v1 5/6] stash: remove the second index in restore_untracked()

[Alban Gruin <alban.gruin@xxxxxxxxx>]

This removes the second index used in restore_untracked().

The call to `read-tree' is replaced by reset_tree() with the appropriate
parameters (no update, no reset).  The environment of `checkout-index'
is no longer modified, and the cache is discarded when it exists.

In do_apply_stash(), the changes are a bit more involved: to avoid
conflicts with the merged index, restore_untracked() is moved after
merge_recursive_generic().

This introduces another problem: the files that were untracked once are
now added to the index, and update_index() would add back those files in
the index.  To avoid this, get_newly_staged() is moved before
restore_untracked().

Signed-off-by: Alban Gruin <alban.gruin@xxxxxxxxx>
---
 builtin/stash.c | 46 +++++++++++++++++-----------------------------
 1 file changed, 17 insertions(+), 29 deletions(-)

diff --git a/builtin/stash.c b/builtin/stash.c
index cbe37cd24b..1eafc1fe8d 100644
--- a/builtin/stash.c
+++ b/builtin/stash.c
@@ -359,29 +359,16 @@ static int restore_untracked(struct object_id *u_tree)
 	int res;
 	struct child_process cp = CHILD_PROCESS_INIT;
 
-	/*
-	 * We need to run restore files from a given index, but without
-	 * affecting the current index, so we use GIT_INDEX_FILE with
-	 * run_command to fork processes that will not interfere.
-	 */
-	cp.git_cmd = 1;
-	argv_array_push(&cp.args, "read-tree");
-	argv_array_push(&cp.args, oid_to_hex(u_tree));
-	argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s",
-			 stash_index_path.buf);
-	if (run_command(&cp)) {
-		remove_path(stash_index_path.buf);
+	if (reset_tree(u_tree, 0, 0))
 		return -1;
-	}
 
 	child_process_init(&cp);
 	cp.git_cmd = 1;
 	argv_array_pushl(&cp.args, "checkout-index", "--all", NULL);
-	argv_array_pushf(&cp.env_array, "GIT_INDEX_FILE=%s",
-			 stash_index_path.buf);
 
 	res = run_command(&cp);
-	remove_path(stash_index_path.buf);
+	discard_cache();
+
 	return res;
 }
 
@@ -395,6 +382,7 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 	struct object_id index_tree;
 	struct commit *result;
 	const struct object_id *bases[1];
+	struct strbuf newly_staged = STRBUF_INIT;
 
 	read_cache_preload(NULL);
 	if (refresh_and_write_cache(REFRESH_QUIET, 0, 0))
@@ -433,9 +421,6 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 		}
 	}
 
-	if (info->has_u && restore_untracked(&info->u_tree))
-		return error(_("could not restore untracked files from stash"));
-
 	init_merge_options(&o, the_repository);
 
 	o.branch1 = "Updated upstream";
@@ -463,24 +448,27 @@ static int do_apply_stash(const char *prefix, struct stash_info *info,
 		return ret;
 	}
 
+	if (!has_index && get_newly_staged(&newly_staged, &c_tree)) {
+		strbuf_release(&newly_staged);
+		return -1;
+	}
+
+	if (info->has_u && restore_untracked(&info->u_tree)) {
+		strbuf_release(&newly_staged);
+		return error(_("could not restore untracked files from stash"));
+	}
+
 	if (has_index) {
 		if (reset_tree(&index_tree, 0, 0))
 			return -1;
 	} else {
-		struct strbuf out = STRBUF_INIT;
-
-		if (get_newly_staged(&out, &c_tree)) {
-			strbuf_release(&out);
-			return -1;
-		}
-
 		if (reset_tree(&c_tree, 0, 1)) {
-			strbuf_release(&out);
+			strbuf_release(&newly_staged);
 			return -1;
 		}
 
-		ret = update_index(&out);
-		strbuf_release(&out);
+		ret = update_index(&newly_staged);
+		strbuf_release(&newly_staged);
 		if (ret)
 			return -1;
 
-- 
2.26.2