From 7acd90b6517e34c2482366d4b960b2bedafdfa89 Mon Sep 17 00:00:00 2001
From: Guillaume Racicot <gufideg@gmail.com>
Date: Mon, 4 Jun 2018 11:18:19 -0400
Subject: [PATCH] Fixed check for compatible string type

---
 include/nlohmann/detail/conversions/from_json.hpp | 4 +---
 include/nlohmann/detail/meta.hpp                  | 3 ++-
 single_include/nlohmann/json.hpp                  | 7 +++----
 3 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/include/nlohmann/detail/conversions/from_json.hpp b/include/nlohmann/detail/conversions/from_json.hpp
index b066b2b4..b71bb0ec 100644
--- a/include/nlohmann/detail/conversions/from_json.hpp
+++ b/include/nlohmann/detail/conversions/from_json.hpp
@@ -75,9 +75,7 @@ template <
     enable_if_t <
         is_compatible_string_type<BasicJsonType, CompatibleStringType>::value and
         not std::is_same<typename BasicJsonType::string_t,
-                         CompatibleStringType>::value and
-        std::is_constructible <
-            BasicJsonType, typename CompatibleStringType::value_type >::value,
+                         CompatibleStringType>::value,
         int > = 0 >
 void from_json(const BasicJsonType& j, CompatibleStringType& s)
 {
diff --git a/include/nlohmann/detail/meta.hpp b/include/nlohmann/detail/meta.hpp
index 780efba8..50200304 100644
--- a/include/nlohmann/detail/meta.hpp
+++ b/include/nlohmann/detail/meta.hpp
@@ -127,7 +127,8 @@ template<class RealType, class CompatibleStringType>
 struct is_compatible_string_type_impl<true, RealType, CompatibleStringType>
 {
     static constexpr auto value =
-        std::is_same<typename RealType::value_type, typename CompatibleStringType::value_type>::value;
+        std::is_same<typename RealType::value_type, typename CompatibleStringType::value_type>::value and
+        std::is_constructible<RealType, CompatibleStringType>::value;
 };
 
 template<class BasicJsonType, class CompatibleObjectType>
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index a886cc9e..555aa1de 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -360,7 +360,8 @@ template<class RealType, class CompatibleStringType>
 struct is_compatible_string_type_impl<true, RealType, CompatibleStringType>
 {
     static constexpr auto value =
-        std::is_same<typename RealType::value_type, typename CompatibleStringType::value_type>::value;
+        std::is_same<typename RealType::value_type, typename CompatibleStringType::value_type>::value and
+        std::is_constructible<RealType, CompatibleStringType>::value;
 };
 
 template<class BasicJsonType, class CompatibleObjectType>
@@ -1001,9 +1002,7 @@ template <
     enable_if_t <
         is_compatible_string_type<BasicJsonType, CompatibleStringType>::value and
         not std::is_same<typename BasicJsonType::string_t,
-                         CompatibleStringType>::value and
-        std::is_constructible <
-            BasicJsonType, typename CompatibleStringType::value_type >::value,
+                         CompatibleStringType>::value,
         int > = 0 >
 void from_json(const BasicJsonType& j, CompatibleStringType& s)
 {