From b5599ef3fc642bc5316e81cd3bfbd10b3bbf07fe Mon Sep 17 00:00:00 2001
From: Jakob Petsovits <jpetso@topologyinc.com>
Date: Wed, 11 Nov 2015 18:16:44 -0500
Subject: [PATCH] Support to-object conversions for
 std::reference_wrapper<const T>.

Previously the conversion would fail because struct object is not
generally provided for the const version of the type, but because
the wrapper would pass down the type unchanged, it would look for
exactly that missing template specialization unsuccessfully.

This is specifically an issue for std::reference_wrapper because
std::cref() returns an std::reference_wrapper<const T>.
---
 .../adaptor/cpp11/reference_wrapper.hpp       |  5 ++-
 test/reference_wrapper_cpp11.cpp              | 38 ++++++++++++++++++-
 2 files changed, 40 insertions(+), 3 deletions(-)

diff --git a/include/msgpack/adaptor/cpp11/reference_wrapper.hpp b/include/msgpack/adaptor/cpp11/reference_wrapper.hpp
index 214a6a7f..59974e67 100644
--- a/include/msgpack/adaptor/cpp11/reference_wrapper.hpp
+++ b/include/msgpack/adaptor/cpp11/reference_wrapper.hpp
@@ -24,6 +24,7 @@
 #include "msgpack/adaptor/check_container_size.hpp"
 
 #include <memory>
+#include <type_traits>
 
 namespace msgpack {
 
@@ -53,14 +54,14 @@ struct pack<std::reference_wrapper<T>> {
 template <typename T>
 struct object<std::reference_wrapper<T> > {
     void operator()(msgpack::object& o, const std::reference_wrapper<T>& v) const {
-        msgpack::adaptor::object<T>()(o, v.get());
+        msgpack::adaptor::object<typename std::remove_const<T>::type>()(o, v.get());
     }
 };
 
 template <typename T>
 struct object_with_zone<std::reference_wrapper<T>> {
     void operator()(msgpack::object::with_zone& o, const std::reference_wrapper<T>& v) const {
-        msgpack::adaptor::object_with_zone<T>()(o, v.get());
+        msgpack::adaptor::object_with_zone<typename std::remove_const<T>::type>()(o, v.get());
     }
 };
 
diff --git a/test/reference_wrapper_cpp11.cpp b/test/reference_wrapper_cpp11.cpp
index b1ed8876..6550af37 100644
--- a/test/reference_wrapper_cpp11.cpp
+++ b/test/reference_wrapper_cpp11.cpp
@@ -17,7 +17,20 @@ TEST(MSGPACK_REFERENCE_WRAPPER, pack_convert)
     msgpack::object_handle oh = msgpack::unpack(ss.str().data(), ss.str().size());
     int i2 = 0;
     std::reference_wrapper<int> val2(i2);
-    oh.get().convert(val2);;
+    oh.get().convert(val2);
+    EXPECT_EQ(i1, i2);
+}
+
+TEST(MSGPACK_REFERENCE_WRAPPER, pack_convert_const)
+{
+    const int i1 = 42;
+    std::reference_wrapper<const int> val1(i1);
+    std::stringstream ss;
+    msgpack::pack(ss, val1);
+    msgpack::object_handle oh = msgpack::unpack(ss.str().data(), ss.str().size());
+    int i2 = 0;
+    std::reference_wrapper<int> val2(i2);
+    oh.get().convert(val2);
     EXPECT_EQ(i1, i2);
 }
 
@@ -44,6 +57,17 @@ TEST(MSGPACK_REFERENCE_WRAPPER, object)
     EXPECT_EQ(i1, i2);
 }
 
+TEST(MSGPACK_REFERENCE_WRAPPER, object_const)
+{
+    const int i1 = 42;
+    std::reference_wrapper<const int> val1(i1);
+    msgpack::object o(val1);
+    int i2 = 0;
+    std::reference_wrapper<int> val2(i2);
+    o.convert(val2);
+    EXPECT_EQ(i1, i2);
+}
+
 TEST(MSGPACK_REFERENCE_WRAPPER, object_with_zone)
 {
     std::string s1 = "ABC";
@@ -56,4 +80,16 @@ TEST(MSGPACK_REFERENCE_WRAPPER, object_with_zone)
     EXPECT_EQ(s1, s2);
 }
 
+TEST(MSGPACK_REFERENCE_WRAPPER, object_with_zone_const)
+{
+    const std::string s1 = "ABC";
+    std::reference_wrapper<const std::string> val1(s1);
+    msgpack::zone z;
+    msgpack::object o(val1, z);
+    std::string s2 = "DE";
+    std::reference_wrapper<std::string> val2(s2);
+    o.convert(val2);
+    EXPECT_EQ(s1, s2);
+}
+
 #endif // !defined(MSGPACK_USE_CPP03)