From 640df2c1f572ddcbab036c94609fd33ab21bab64 Mon Sep 17 00:00:00 2001
From: Wouter van Oortmerssen <aardappel@gmail.com>
Date: Thu, 11 Apr 2019 14:18:21 -0700
Subject: [PATCH] Allow Set() methods to handle reference types

Change-Id: I487ded77d28490189dd5d38236cb04bffaf5f11a
---
 samples/monster_generated.h    |  6 +++---
 src/idl_gen_cpp.cpp            |  7 +++----
 tests/monster_test_generated.h | 12 ++++++------
 3 files changed, 12 insertions(+), 13 deletions(-)

diff --git a/samples/monster_generated.h b/samples/monster_generated.h
index e89ec3a51..d9d64793d 100644
--- a/samples/monster_generated.h
+++ b/samples/monster_generated.h
@@ -119,12 +119,12 @@ struct EquipmentUnion {
   void Reset();
 
 #ifndef FLATBUFFERS_CPP98_STL
-  template <typename T>
+  template <typename T, typename RT = typename std::remove_reference<T>::type>
   void Set(T&& val) {
     Reset();
-    type = EquipmentTraits<typename T::TableType>::enum_value;
+    type = EquipmentTraits<typename RT::TableType>::enum_value;
     if (type != Equipment_NONE) {
-      value = new T(std::forward<T>(val));
+      value = new RT(std::forward<T>(val));
     }
   }
 #endif  // FLATBUFFERS_CPP98_STL
diff --git a/src/idl_gen_cpp.cpp b/src/idl_gen_cpp.cpp
index 17da0693e..0c964d4bc 100644
--- a/src/idl_gen_cpp.cpp
+++ b/src/idl_gen_cpp.cpp
@@ -1096,13 +1096,12 @@ class CppGenerator : public BaseGenerator {
       code_ += "";
       if (!enum_def.uses_multiple_type_instances) {
         code_ += "#ifndef FLATBUFFERS_CPP98_STL";
-        code_ += "  template <typename T>";
+        code_ += "  template <typename T, typename RT = typename std::remove_reference<T>::type>";
         code_ += "  void Set(T&& val) {";
         code_ += "    Reset();";
-        code_ +=
-            "    type = {{NAME}}Traits<typename T::TableType>::enum_value;";
+        code_ += "    type = {{NAME}}Traits<typename RT::TableType>::enum_value;";
         code_ += "    if (type != {{NONE}}) {";
-        code_ += "      value = new T(std::forward<T>(val));";
+        code_ += "      value = new RT(std::forward<T>(val));";
         code_ += "    }";
         code_ += "  }";
         code_ += "#endif  // FLATBUFFERS_CPP98_STL";
diff --git a/tests/monster_test_generated.h b/tests/monster_test_generated.h
index f98e86b71..a55a42754 100644
--- a/tests/monster_test_generated.h
+++ b/tests/monster_test_generated.h
@@ -207,12 +207,12 @@ struct AnyUnion {
   void Reset();
 
 #ifndef FLATBUFFERS_CPP98_STL
-  template <typename T>
+  template <typename T, typename RT = typename std::remove_reference<T>::type>
   void Set(T&& val) {
     Reset();
-    type = AnyTraits<typename T::TableType>::enum_value;
+    type = AnyTraits<typename RT::TableType>::enum_value;
     if (type != Any_NONE) {
-      value = new T(std::forward<T>(val));
+      value = new RT(std::forward<T>(val));
     }
   }
 #endif  // FLATBUFFERS_CPP98_STL
@@ -348,12 +348,12 @@ struct AnyUniqueAliasesUnion {
   void Reset();
 
 #ifndef FLATBUFFERS_CPP98_STL
-  template <typename T>
+  template <typename T, typename RT = typename std::remove_reference<T>::type>
   void Set(T&& val) {
     Reset();
-    type = AnyUniqueAliasesTraits<typename T::TableType>::enum_value;
+    type = AnyUniqueAliasesTraits<typename RT::TableType>::enum_value;
     if (type != AnyUniqueAliases_NONE) {
-      value = new T(std::forward<T>(val));
+      value = new RT(std::forward<T>(val));
     }
   }
 #endif  // FLATBUFFERS_CPP98_STL