From ec955f08b47ab7cb81f6e4a4c3e7b331ddf50f71 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Art=C3=B6m=20Bakri=20Al-Sarmini?= <3sz3tt+git@gmail.com>
Date: Sun, 12 Apr 2020 22:32:39 +0300
Subject: [PATCH] Templatize basic_json ctor from json_ref

Upstream-Status: Backport [https://github.com/nlohmann/json/commit/ec955f08b47ab7cb81f6e4a4c3e7b331ddf50f71]
Signed-off-by: Andrew Geissler <geissonator@gmail.com>

---
 include/nlohmann/detail/meta/type_traits.hpp | 13 ++++++++++++
 include/nlohmann/json.hpp                    |  8 ++++----
 single_include/nlohmann/json.hpp             | 21 ++++++++++++++++----
 3 files changed, 34 insertions(+), 8 deletions(-)

diff --git a/include/nlohmann/detail/meta/type_traits.hpp b/include/nlohmann/detail/meta/type_traits.hpp
index 280f6953..dd0b3084 100644
--- a/include/nlohmann/detail/meta/type_traits.hpp
+++ b/include/nlohmann/detail/meta/type_traits.hpp
@@ -41,6 +41,19 @@ template<typename> struct is_basic_json : std::false_type {};
 NLOHMANN_BASIC_JSON_TPL_DECLARATION
 struct is_basic_json<NLOHMANN_BASIC_JSON_TPL> : std::true_type {};

+//////////////////////
+// jspn_ref helpers //
+//////////////////////
+
+template <typename>
+class json_ref;
+
+template<typename>
+struct is_json_ref : std::false_type {};
+
+template <typename T>
+struct is_json_ref<json_ref<T>> : std::true_type {};
+
 //////////////////////////
 // aliases for detected //
 //////////////////////////
diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index 336d69fe..0598efc8 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -1773,10 +1773,10 @@ class basic_json
     // other constructors and destructor //
     ///////////////////////////////////////

-    /// @private
-    basic_json(const detail::json_ref<basic_json>& ref)
-        : basic_json(ref.moved_or_copied())
-    {}
+    template <typename JsonRef,
+              detail::enable_if_t<detail::conjunction<detail::is_json_ref<JsonRef>,
+                                  std::is_same<typename JsonRef::value_type, basic_json>>::value, int> = 0 >
+    basic_json(const JsonRef& ref) : basic_json(ref.moved_or_copied()) {}

     /*!
     @brief copy constructor
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index 09464f3b..8927180e 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -2794,6 +2794,19 @@ template<typename> struct is_basic_json : std::false_type {};
 NLOHMANN_BASIC_JSON_TPL_DECLARATION
 struct is_basic_json<NLOHMANN_BASIC_JSON_TPL> : std::true_type {};

+//////////////////////
+// jspn_ref helpers //
+//////////////////////
+
+template <typename>
+class json_ref;
+
+template<typename>
+struct is_json_ref : std::false_type {};
+
+template <typename T>
+struct is_json_ref<json_ref<T>> : std::true_type {};
+
 //////////////////////////
 // aliases for detected //
 //////////////////////////
@@ -16632,10 +16645,10 @@ class basic_json
     // other constructors and destructor //
     ///////////////////////////////////////

-    /// @private
-    basic_json(const detail::json_ref<basic_json>& ref)
-        : basic_json(ref.moved_or_copied())
-    {}
+    template <typename JsonRef,
+              detail::enable_if_t<detail::conjunction<detail::is_json_ref<JsonRef>,
+                                  std::is_same<typename JsonRef::value_type, basic_json>>::value, int> = 0 >
+    basic_json(const JsonRef& ref) : basic_json(ref.moved_or_copied()) {}

     /*!
     @brief copy constructor
--
2.21.0 (Apple Git-122)