modify const to const &

paddle/fluid/operators/detail/checkpoint.cc

@@ -22,7 +22,7 @@ namespace framework {
 namespace details {
 Checkpoint::Save(const framework::Scope& scope, const platform::Place& place,
                  const std::string& save_dir, const std::string& var_name,
-                 const bool overwrite) {
+                 const bool& overwrite) {
   auto* var = scope.FindVar(var_name);
   PADDLE_ENFORCE(var != nullptr, "Cannot find variable %s for save_op",
                  var_name);

paddle/fluid/operators/detail/checkpoint.h

@@ -24,7 +24,7 @@ class Checkpoint {
  public:
   static void Save(const framework::Scope& scope, const platform::Place& place,
                    const std::string& save_dir, const std::string& var_name,
-                   const bool overwrite);
+                   const bool& overwrite);
 
   static void Load();
 }