From 435fc32a697188a43c86c559e60069711317ffc9 Mon Sep 17 00:00:00 2001
From: "Andreas C. Osowski" <andreas@osowski.de>
Date: Tue, 24 Apr 2018 21:58:51 +0200
Subject: [PATCH] Fix operator== overload ambiguity

---
 include/nlohmann/json.hpp        | 12 ++++++++----
 single_include/nlohmann/json.hpp | 12 ++++++++----
 2 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index 54e66d90fa..5734f7a67f 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -5533,8 +5533,10 @@ class basic_json
     @brief comparison: equal
     @copydoc operator==(const_reference, const_reference)
     */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    template < typename ScalarType, typename std::enable_if <
+                   std::is_scalar<ScalarType>::value, int >::type = 0,
+               typename std::enable_if <
+                   std::is_same<std::nullptr_t, std::remove_cv<ScalarType>>::value, int >::type = 0 >
     friend bool operator==(const_reference lhs, const ScalarType rhs) noexcept
     {
         return (lhs == basic_json(rhs));
@@ -5544,8 +5546,10 @@ class basic_json
     @brief comparison: equal
     @copydoc operator==(const_reference, const_reference)
     */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    template < typename ScalarType, typename std::enable_if <
+                   std::is_scalar<ScalarType>::value, int >::type = 0,
+               typename std::enable_if <
+                   std::is_same<std::nullptr_t, std::remove_cv<ScalarType>>::value, int >::type = 0 >
     friend bool operator==(const ScalarType lhs, const_reference rhs) noexcept
     {
         return (basic_json(lhs) == rhs);
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index c9ef7581af..c2e816e82a 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -15174,8 +15174,10 @@ class basic_json
     @brief comparison: equal
     @copydoc operator==(const_reference, const_reference)
     */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    template < typename ScalarType, typename std::enable_if <
+                   std::is_scalar<ScalarType>::value, int >::type = 0,
+               typename std::enable_if <
+                   !std::is_same<std::nullptr_t, std::remove_cv<ScalarType>>::value, int >::type = 0 >
     friend bool operator==(const_reference lhs, const ScalarType rhs) noexcept
     {
         return (lhs == basic_json(rhs));
@@ -15185,8 +15187,10 @@ class basic_json
     @brief comparison: equal
     @copydoc operator==(const_reference, const_reference)
     */
-    template<typename ScalarType, typename std::enable_if<
-                 std::is_scalar<ScalarType>::value, int>::type = 0>
+    template < typename ScalarType, typename std::enable_if <
+                   std::is_scalar<ScalarType>::value, int >::type = 0,
+               typename std::enable_if <
+                   !std::is_same<std::nullptr_t, std::remove_cv<ScalarType>>::value, int >::type = 0 >
     friend bool operator==(const ScalarType lhs, const_reference rhs) noexcept
     {
         return (basic_json(lhs) == rhs);