Correct -use-separate-module behaviour

src/entity.cpp

@@ -338,6 +338,9 @@ gb_internal Entity *alloc_entity(EntityKind kind, Scope *scope, Token token, Typ
 	entity->token  = token;
 	entity->type   = type;
 	entity->id     = 1 + global_entity_id.fetch_add(1);
+	if (token.pos.file_id) {
+		entity->file = thread_safe_get_ast_file_from_id(token.pos.file_id);
+	}
 	return entity;
 }