From d812fa5edc0ed073b8ab723259b3e25fabe1bfb6 Mon Sep 17 00:00:00 2001
From: Uy Ha <hchanuy@gmail.com>
Date: Tue, 2 Apr 2024 01:22:07 +0000
Subject: [PATCH] Fix compilation error when `std::variant` has the same types

---
 include/msgpack/v1/adaptor/cpp17/variant.hpp |  4 ++--
 test/msgpack_cpp17.cpp                       | 22 ++++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/include/msgpack/v1/adaptor/cpp17/variant.hpp b/include/msgpack/v1/adaptor/cpp17/variant.hpp
index 2ddb6b6e6..d96a15eb0 100644
--- a/include/msgpack/v1/adaptor/cpp17/variant.hpp
+++ b/include/msgpack/v1/adaptor/cpp17/variant.hpp
@@ -40,11 +40,11 @@ Variant construct_variant(
     std::index_sequence<current_index, indices...>
 ) {
     if constexpr(sizeof...(Ts) == 0) {
-        return object.as<T>();
+        return Variant{std::in_place_index<current_index>, object.as<T>()};
     }
     else {
         if (index == current_index) {
-            return object.as<T>();
+            return Variant{std::in_place_index<current_index>, object.as<T>()};
         }
         return construct_variant<Variant, Ts...>(
             index,
diff --git a/test/msgpack_cpp17.cpp b/test/msgpack_cpp17.cpp
index b20c04ccd..be3d9d410 100644
--- a/test/msgpack_cpp17.cpp
+++ b/test/msgpack_cpp17.cpp
@@ -474,6 +474,28 @@ BOOST_AUTO_TEST_CASE(variant_pack_unpack_as) {
         oh.get().as<std::variant<bool, int, float, double> >();
     BOOST_CHECK(val1 == val2);
     BOOST_CHECK_THROW((oh.get().as<std::variant<bool>>()), msgpack::type_error);
+
+    {
+      std::stringstream same_ss;
+      std::variant<int, float, int> same_expected{std::in_place_index<2>, 2};
+      msgpack::pack(same_ss, same_expected);
+      std::string const& same_str = same_ss.str();
+      msgpack::object_handle same_oh =
+          msgpack::unpack(same_str.data(), same_str.size());
+      std::variant<int, float, int> same_actual = same_oh->as<std::variant<int, float, int>>();
+      BOOST_CHECK(same_expected == same_actual);
+    }
+
+    {
+      std::stringstream same_ss;
+      std::variant<int, int> same_expected{std::in_place_index<1>, 2};
+      msgpack::pack(same_ss, same_expected);
+      std::string const& same_str = same_ss.str();
+      msgpack::object_handle same_oh =
+          msgpack::unpack(same_str.data(), same_str.size());
+      std::variant<int, int> same_actual = same_oh->as<std::variant<int, int>>();
+      BOOST_CHECK(same_expected == same_actual);
+    }
 }
 
 BOOST_AUTO_TEST_CASE(variant_with_zone) {