From a653131cf038599826166846c2203b4345f2e0b5 Mon Sep 17 00:00:00 2001
From: Niels Lohmann <mail@nlohmann.me>
Date: Fri, 20 Aug 2021 13:42:49 +0200
Subject: [PATCH] :rotating_light: fix warnings

---
 include/nlohmann/detail/meta/type_traits.hpp |  9 ++++-----
 include/nlohmann/json.hpp                    |  4 +++-
 single_include/nlohmann/json.hpp             | 13 +++++++------
 3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/include/nlohmann/detail/meta/type_traits.hpp b/include/nlohmann/detail/meta/type_traits.hpp
index cd31259fb..5f0c097b7 100644
--- a/include/nlohmann/detail/meta/type_traits.hpp
+++ b/include/nlohmann/detail/meta/type_traits.hpp
@@ -451,20 +451,19 @@ T conditional_static_cast(U value)
 
 // helper to check if a type has bucket_count function (and hence can tell a std::map and a std::unordered_map apart)
 template <typename T>
-class has_bucket_count
+struct has_bucket_count
 {
-    typedef char one;
+    using one = char;
 
     struct two
     {
-        char x[2];
+        char x[2]; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
     };
 
     template <typename C> static one test( decltype(&C::bucket_count) ) ;
     template <typename C> static two test(...);
 
-  public:
-    enum { value = sizeof(test<T>(0)) == sizeof(char) };
+    enum { value = sizeof(test<T>(nullptr)) == sizeof(char) };
 };
 
 }  // namespace detail
diff --git a/include/nlohmann/json.hpp b/include/nlohmann/json.hpp
index 5a44a2d45..e15e2c044 100644
--- a/include/nlohmann/json.hpp
+++ b/include/nlohmann/json.hpp
@@ -422,8 +422,10 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     // Use transparent comparator if possible, combined with perfect forwarding
     // on find() and count() calls prevents unnecessary string construction.
     using object_comparator_t = std::less<>;
+    using key_equal_t = std::equal_to<>;
 #else
     using object_comparator_t = std::less<StringType>;
+    using key_equal_t = std::equal_to<StringType>;
 #endif
 
     /*!
@@ -515,7 +517,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                      std::unordered_map<StringType,
                      basic_json,
                      std::hash<StringType>,
-                     std::equal_to<StringType>,
+                     key_equal_t,
                      AllocatorType<std::pair<const StringType,
                      basic_json>>>,
 
diff --git a/single_include/nlohmann/json.hpp b/single_include/nlohmann/json.hpp
index fc15f4cdb..130408ae3 100644
--- a/single_include/nlohmann/json.hpp
+++ b/single_include/nlohmann/json.hpp
@@ -3862,20 +3862,19 @@ T conditional_static_cast(U value)
 
 // helper to check if a type has bucket_count function (and hence can tell a std::map and a std::unordered_map apart)
 template <typename T>
-class has_bucket_count
+struct has_bucket_count
 {
-    typedef char one;
+    using one = char;
 
     struct two
     {
-        char x[2];
+        char x[2]; // NOLINT(cppcoreguidelines-avoid-c-arrays,hicpp-avoid-c-arrays,modernize-avoid-c-arrays)
     };
 
     template <typename C> static one test( decltype(&C::bucket_count) ) ;
     template <typename C> static two test(...);
 
-  public:
-    enum { value = sizeof(test<T>(0)) == sizeof(char) };
+    enum { value = sizeof(test<T>(nullptr)) == sizeof(char) };
 };
 
 }  // namespace detail
@@ -17823,8 +17822,10 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
     // Use transparent comparator if possible, combined with perfect forwarding
     // on find() and count() calls prevents unnecessary string construction.
     using object_comparator_t = std::less<>;
+    using key_equal_t = std::equal_to<>;
 #else
     using object_comparator_t = std::less<StringType>;
+    using key_equal_t = std::equal_to<StringType>;
 #endif
 
     /*!
@@ -17916,7 +17917,7 @@ class basic_json // NOLINT(cppcoreguidelines-special-member-functions,hicpp-spec
                      std::unordered_map<StringType,
                      basic_json,
                      std::hash<StringType>,
-                     std::equal_to<StringType>,
+                     key_equal_t,
                      AllocatorType<std::pair<const StringType,
                      basic_json>>>,