merge-ort: add a new toplevel_dir field

Due to the string-equality-iff-pointer-equality requirements placed on
merged_info.directory_name, apply_directory_rename_modifications() will
need to have access to the exact toplevel directory name string pointer
and can't just use a new empty string.  Store it in a field that we can
use.

Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: newren

merge-ort.c

@@ -168,12 +168,15 @@ struct merge_options_internal {
 	struct rename_info renames;
 
 	/*
-	 * current_dir_name: temporary var used in collect_merge_info_callback()
+	 * current_dir_name, toplevel_dir: temporary vars
 	 *
-	 * Used to set merged_info.directory_name; see documentation for that
-	 * variable and the requirements placed on that field.
+	 * These are used in collect_merge_info_callback(), and will set the
+	 * various merged_info.directory_name for the various paths we get;
+	 * see documentation for that variable and the requirements placed on
+	 * that field.
 	 */
 	const char *current_dir_name;
+	const char *toplevel_dir;
 
 	/* call_depth: recursion level counter for merging merge bases */
 	int call_depth;
@@ -682,10 +685,10 @@ static int collect_merge_info(struct merge_options *opt,
 	int ret;
 	struct tree_desc t[3];
 	struct traverse_info info;
-	const char *toplevel_dir_placeholder = "";
 
-	opt->priv->current_dir_name = toplevel_dir_placeholder;
-	setup_traverse_info(&info, toplevel_dir_placeholder);
+	opt->priv->toplevel_dir = "";
+	opt->priv->current_dir_name = opt->priv->toplevel_dir;
+	setup_traverse_info(&info, opt->priv->toplevel_dir);
 	info.fn = collect_merge_info_callback;
 	info.data = opt;
 	info.show_all_errors = 1;