From 543158bbf3efe123d59832e26a89ebf63c9e5eb7 Mon Sep 17 00:00:00 2001
From: Colby Haskell <cchaskel@usc.edu>
Date: Mon, 13 Nov 2023 13:27:14 -0500
Subject: [PATCH] Add to_char_type function to custom char_traits

---
 include/nlohmann/detail/meta/type_traits.hpp | 18 ++++++++++++++----
 single_include/nlohmann/json.hpp             | 18 ++++++++++++++----
 2 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/include/nlohmann/detail/meta/type_traits.hpp b/include/nlohmann/detail/meta/type_traits.hpp
index b1e7022ab1..82faf0de8c 100644
--- a/include/nlohmann/detail/meta/type_traits.hpp
+++ b/include/nlohmann/detail/meta/type_traits.hpp
@@ -199,12 +199,17 @@ struct char_traits<unsigned char> : std::char_traits<char>
     using int_type = uint64_t;
 
     // Redefine to_int_type function
-    static int_type to_int_type(char_type c)
+    static int_type to_int_type(char_type c) noexcept
     {
         return static_cast<int_type>(c);
     }
 
-    static constexpr int_type eof()
+    static char_type to_char_type(int_type i) noexcept
+    {
+        return static_cast<char_type>(i);
+    }
+
+    static constexpr int_type eof() noexcept
     {
         return static_cast<int_type>(EOF);
     }
@@ -218,12 +223,17 @@ struct char_traits<signed char> : std::char_traits<char>
     using int_type = uint64_t;
 
     // Redefine to_int_type function
-    static int_type to_int_type(char_type c)
+    static int_type to_int_type(char_type c) noexcept
     {
         return static_cast<int_type>(c);
     }
 
-    static constexpr int_type eof()
+    static char_type to_char_type(int_type i) noexcept
+    {
+        return static_cast<char_type>(i);
+    }
+
+    static constexpr int_type eof() noexcept
     {
         return static_cast<int_type>(EOF);
     }
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index a930988ff4..09db5f1dc1 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -3612,12 +3612,17 @@ struct char_traits<unsigned char> : std::char_traits<char>
     using int_type = uint64_t;
 
     // Redefine to_int_type function
-    static int_type to_int_type(char_type c)
+    static int_type to_int_type(char_type c) noexcept
     {
         return static_cast<int_type>(c);
     }
 
-    static constexpr int_type eof()
+    static char_type to_char_type(int_type i) noexcept
+    {
+        return static_cast<char_type>(i);
+    }
+
+    static constexpr int_type eof() noexcept
     {
         return static_cast<int_type>(EOF);
     }
@@ -3631,12 +3636,17 @@ struct char_traits<signed char> : std::char_traits<char>
     using int_type = uint64_t;
 
     // Redefine to_int_type function
-    static int_type to_int_type(char_type c)
+    static int_type to_int_type(char_type c) noexcept
     {
         return static_cast<int_type>(c);
     }
 
-    static constexpr int_type eof()
+    static char_type to_char_type(int_type i) noexcept
+    {
+        return static_cast<char_type>(i);
+    }
+
+    static constexpr int_type eof() noexcept
     {
         return static_cast<int_type>(EOF);
     }