From 2eb72beedb8ff6526978de38c8b286b887f78b21 Mon Sep 17 00:00:00 2001
From: "Juan Carlos Arevalo Baeza (JCAB)" <jcab@ntdev.microsoft.com>
Date: Fri, 8 Dec 2023 10:35:09 -0800
Subject: [PATCH] Fix the issue in the relevant `to_json` overload.

Select the correct json type depending on the signedness of the enum's underlying type.
This fixes the new checks in the unit test.
---
 include/nlohmann/detail/conversions/to_json.hpp | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/nlohmann/detail/conversions/to_json.hpp b/include/nlohmann/detail/conversions/to_json.hpp
index e39b7797d..8a8610821 100644
--- a/include/nlohmann/detail/conversions/to_json.hpp
+++ b/include/nlohmann/detail/conversions/to_json.hpp
@@ -320,7 +320,14 @@ template<typename BasicJsonType, typename EnumType,
 inline void to_json(BasicJsonType& j, EnumType e) noexcept
 {
     using underlying_type = typename std::underlying_type<EnumType>::type;
-    external_constructor<value_t::number_integer>::construct(j, static_cast<underlying_type>(e));
+    if (std::is_unsigned<underlying_type>::value)
+    {
+        external_constructor<value_t::number_unsigned>::construct(j, static_cast<underlying_type>(e));
+    }
+    else
+    {
+        external_constructor<value_t::number_integer>::construct(j, static_cast<underlying_type>(e));
+    }
 }
 #endif  // JSON_DISABLE_ENUM_SERIALIZATION