From e9c84befa15d35339b2b7f326fcb8921c1c4c907 Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Sat, 26 Sep 2026 10:07:22 +0200
Subject: [PATCH] Keep the created pointer rather than an uninitialized
 json_value

clang-tidy reported the json_value unions declared in the string, array,
and object constructors of to_json.hpp as uninitialized
(cppcoreguidelines-pro-type-member-init). Assign the created pointer to
the member directly once the old value is destroyed.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>
---
 include/nlohmann/detail/conversions/to_json.hpp | 15 ++++++---------
 single_include/nlohmann/json.hpp                | 15 ++++++---------
 2 files changed, 12 insertions(+), 18 deletions(-)

diff --git a/include/nlohmann/detail/conversions/to_json.hpp b/include/nlohmann/detail/conversions/to_json.hpp
index aa8d35a0f..7ba3ab71f 100644
--- a/include/nlohmann/detail/conversions/to_json.hpp
+++ b/include/nlohmann/detail/conversions/to_json.hpp
@@ -91,11 +91,10 @@ struct external_constructor<value_t::string>
                              int > = 0 >
     static void construct(BasicJsonType& j, const CompatibleStringType& str)
     {
-        typename BasicJsonType::json_value value;
-        value.string = j.template create<typename BasicJsonType::string_t>(str);
+        auto* created = j.template create<typename BasicJsonType::string_t>(str);
         j.m_data.m_value.destroy(j.m_data.m_type);
         j.m_data.m_type = value_t::string;
-        j.m_data.m_value = value;
+        j.m_data.m_value.string = created;
         j.assert_invariant();
     }
 };
@@ -199,11 +198,10 @@ struct external_constructor<value_t::array>
         using std::begin;
         using std::end;
 
-        typename BasicJsonType::json_value value;
-        value.array = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
+        auto* created = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
         j.m_data.m_value.destroy(j.m_data.m_type);
         j.m_data.m_type = value_t::array;
-        j.m_data.m_value = value;
+        j.m_data.m_value.array = created;
         j.set_parents();
         j.assert_invariant();
     }
@@ -293,11 +291,10 @@ struct external_constructor<value_t::object>
         using std::begin;
         using std::end;
 
-        typename BasicJsonType::json_value value;
-        value.object = j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj));
+        auto* created = j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj));
         j.m_data.m_value.destroy(j.m_data.m_type);
         j.m_data.m_type = value_t::object;
-        j.m_data.m_value = value;
+        j.m_data.m_value.object = created;
         j.set_parents();
         j.assert_invariant();
     }
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 3f74e166f..118f1cefe 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -6620,11 +6620,10 @@ struct external_constructor<value_t::string>
                              int > = 0 >
     static void construct(BasicJsonType& j, const CompatibleStringType& str)
     {
-        typename BasicJsonType::json_value value;
-        value.string = j.template create<typename BasicJsonType::string_t>(str);
+        auto* created = j.template create<typename BasicJsonType::string_t>(str);
         j.m_data.m_value.destroy(j.m_data.m_type);
         j.m_data.m_type = value_t::string;
-        j.m_data.m_value = value;
+        j.m_data.m_value.string = created;
         j.assert_invariant();
     }
 };
@@ -6728,11 +6727,10 @@ struct external_constructor<value_t::array>
         using std::begin;
         using std::end;
 
-        typename BasicJsonType::json_value value;
-        value.array = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
+        auto* created = j.template create<typename BasicJsonType::array_t>(begin(arr), end(arr));
         j.m_data.m_value.destroy(j.m_data.m_type);
         j.m_data.m_type = value_t::array;
-        j.m_data.m_value = value;
+        j.m_data.m_value.array = created;
         j.set_parents();
         j.assert_invariant();
     }
@@ -6822,11 +6820,10 @@ struct external_constructor<value_t::object>
         using std::begin;
         using std::end;
 
-        typename BasicJsonType::json_value value;
-        value.object = j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj));
+        auto* created = j.template create<typename BasicJsonType::object_t>(begin(obj), end(obj));
         j.m_data.m_value.destroy(j.m_data.m_type);
         j.m_data.m_type = value_t::object;
-        j.m_data.m_value = value;
+        j.m_data.m_value.object = created;
         j.set_parents();
         j.assert_invariant();
     }