From 857953b39a41f8d657c1fc31eee7299a308d88ce Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Mon, 28 Sep 2026 22:31:11 +0200
Subject: [PATCH] Name JSON types without a basic_json value

basic_json::type_name() now calls detail::value_type_name(value_t), so
that code which reports types without a basic_json value at hand, such as
the zero-copy view, uses the same names in its exception messages. No
change in behavior.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---
 include/nlohmann/detail/value_t.hpp | 33 +++++++++++++++++
 include/nlohmann/json.hpp           | 24 +-----------
 single_include/nlohmann/json.hpp    | 57 +++++++++++++++++------------
 3 files changed, 68 insertions(+), 46 deletions(-)

diff --git a/include/nlohmann/detail/value_t.hpp b/include/nlohmann/detail/value_t.hpp
index 9fc217bcc..52b947ffe 100644
--- a/include/nlohmann/detail/value_t.hpp
+++ b/include/nlohmann/detail/value_t.hpp
@@ -67,6 +67,39 @@ enum class value_t : std::uint8_t
     discarded         ///< discarded by the parser callback function
 };
 
+/*!
+@brief the name of a JSON type, as returned by basic_json::type_name()
+
+Used in exception messages; also by code that reports types without a
+basic_json value at hand (such as the zero-copy view).
+*/
+inline const char* value_type_name(const value_t t) noexcept
+{
+    switch (t)
+    {
+        case value_t::null:
+            return "null";
+        case value_t::object:
+            return "object";
+        case value_t::array:
+            return "array";
+        case value_t::string:
+            return "string";
+        case value_t::boolean:
+            return "boolean";
+        case value_t::binary:
+            return "binary";
+        case value_t::discarded:
+            return "discarded";
+        case value_t::number_integer:
+        case value_t::number_unsigned:
+        case value_t::number_float:
+            return "number";
+        default:
+            return "invalid";
+    }
+}
+
 /*!
 @brief comparison operator for JSON types
 
diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index 9dd25ba40..8badc3694 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -5067,29 +5067,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     JSON_HEDLEY_RETURNS_NON_NULL
     const char* type_name() const noexcept
     {
-        switch (m_data.m_type)
-        {
-            case value_t::null:
-                return "null";
-            case value_t::object:
-                return "object";
-            case value_t::array:
-                return "array";
-            case value_t::string:
-                return "string";
-            case value_t::boolean:
-                return "boolean";
-            case value_t::binary:
-                return "binary";
-            case value_t::discarded:
-                return "discarded";
-            case value_t::number_integer:
-            case value_t::number_unsigned:
-            case value_t::number_float:
-                return "number";
-            default:
-                return "invalid";
-        }
+        return detail::value_type_name(m_data.m_type);
     }
 
   JSON_PRIVATE_UNLESS_TESTED:
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index d1cf50a08..73b13f51f 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -3381,6 +3381,39 @@ enum class value_t : std::uint8_t
     discarded         ///< discarded by the parser callback function
 };
 
+/*!
+@brief the name of a JSON type, as returned by basic_json::type_name()
+
+Used in exception messages; also by code that reports types without a
+basic_json value at hand (such as the zero-copy view).
+*/
+inline const char* value_type_name(const value_t t) noexcept
+{
+    switch (t)
+    {
+        case value_t::null:
+            return "null";
+        case value_t::object:
+            return "object";
+        case value_t::array:
+            return "array";
+        case value_t::string:
+            return "string";
+        case value_t::boolean:
+            return "boolean";
+        case value_t::binary:
+            return "binary";
+        case value_t::discarded:
+            return "discarded";
+        case value_t::number_integer:
+        case value_t::number_unsigned:
+        case value_t::number_float:
+            return "number";
+        default:
+            return "invalid";
+    }
+}
+
 /*!
 @brief comparison operator for JSON types
 
@@ -32023,29 +32056,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     JSON_HEDLEY_RETURNS_NON_NULL
     const char* type_name() const noexcept
     {
-        switch (m_data.m_type)
-        {
-            case value_t::null:
-                return "null";
-            case value_t::object:
-                return "object";
-            case value_t::array:
-                return "array";
-            case value_t::string:
-                return "string";
-            case value_t::boolean:
-                return "boolean";
-            case value_t::binary:
-                return "binary";
-            case value_t::discarded:
-                return "discarded";
-            case value_t::number_integer:
-            case value_t::number_unsigned:
-            case value_t::number_float:
-                return "number";
-            default:
-                return "invalid";
-        }
+        return detail::value_type_name(m_data.m_type);
     }
 
   JSON_PRIVATE_UNLESS_TESTED: