diffcore-rename: extend cleanup_dir_rename_info()

When diffcore_rename_extended() is passed a NULL dir_rename_count, we
will still want to create a temporary one for use by
find_basename_matches(), but have it fully deallocated before
diffcore_rename_extended() returns.  However, when
diffcore_rename_extended() is passed a dir_rename_count, we want to fill
that strmap with appropriate values and return it.  However, for our
interim purposes we may also add entries corresponding to directories
that cannot have been renamed due to still existing on both sides.

Extend cleanup_dir_rename_info() to handle these two different cases,
cleaning up the relevant bits of information for each case.

Reviewed-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diffcore-rename.c

@@ -543,8 +543,15 @@ void partial_clear_dir_rename_count(struct strmap *dir_rename_count)
 	strmap_partial_clear(dir_rename_count, 1);
 }
 
-static void cleanup_dir_rename_info(struct dir_rename_info *info)
+static void cleanup_dir_rename_info(struct dir_rename_info *info,
+				    struct strset *dirs_removed,
+				    int keep_dir_rename_count)
 {
+	struct hashmap_iter iter;
+	struct strmap_entry *entry;
+	struct string_list to_remove = STRING_LIST_INIT_NODUP;
+	int i;
+
 	if (!info->setup)
 		return;
 
@@ -555,8 +562,33 @@ static void cleanup_dir_rename_info(struct dir_rename_info *info)
 	strmap_clear(&info->dir_rename_guess, 1);
 
 	/* dir_rename_count */
-	partial_clear_dir_rename_count(info->dir_rename_count);
-	strmap_clear(info->dir_rename_count, 1);
+	if (!keep_dir_rename_count) {
+		partial_clear_dir_rename_count(info->dir_rename_count);
+		strmap_clear(info->dir_rename_count, 1);
+		FREE_AND_NULL(info->dir_rename_count);
+		return;
+	}
+
+	/*
+	 * Although dir_rename_count was passed in
+	 * diffcore_rename_extended() and we want to keep it around and
+	 * return it to that caller, we first want to remove any data
+	 * associated with directories that weren't renamed.
+	 */
+	strmap_for_each_entry(info->dir_rename_count, &iter, entry) {
+		const char *source_dir = entry->key;
+		struct strintmap *counts = entry->value;
+
+		if (!strset_contains(dirs_removed, source_dir)) {
+			string_list_append(&to_remove, source_dir);
+			strintmap_clear(counts);
+			continue;
+		}
+	}
+	for (i = 0; i < to_remove.nr; ++i)
+		strmap_remove(info->dir_rename_count,
+			      to_remove.items[i].string, 1);
+	string_list_clear(&to_remove, 0);
 }
 
 static const char *get_basename(const char *filename)
@@ -1218,7 +1250,7 @@ void diffcore_rename_extended(struct diff_options *options,
 		if (rename_dst[i].filespec_to_free)
 			free_filespec(rename_dst[i].filespec_to_free);
 
-	cleanup_dir_rename_info(&info);
+	cleanup_dir_rename_info(&info, dirs_removed, dir_rename_count != NULL);
 	FREE_AND_NULL(rename_dst);
 	rename_dst_nr = rename_dst_alloc = 0;
 	FREE_AND_NULL(rename_src);