Fix #1647: non-member operator== breaks enum (de)serialization.

include/nlohmann/json.hpp

@@ -2633,11 +2633,11 @@ class basic_json
                                  detail::has_non_default_from_json<basic_json_t, ValueType>::value,
                                  int> = 0>
     ValueType get() const noexcept(noexcept(
-                                       JSONSerializer<ValueTypeCV>::from_json(std::declval<const basic_json_t&>())))
+                                       JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>())))
     {
         static_assert(not std::is_reference<ValueTypeCV>::value,
                       "get() cannot be used with reference types, you might want to use get_ref()");
-        return JSONSerializer<ValueTypeCV>::from_json(*this);
+        return JSONSerializer<ValueType>::from_json(*this);
     }
 
     /*!
@@ -8062,7 +8062,7 @@ struct hash<nlohmann::json>
 /// @note: do not remove the space after '<',
 ///        see https://github.com/nlohmann/json/pull/679
 template<>
-struct less< ::nlohmann::detail::value_t>
+struct less<::nlohmann::detail::value_t>
 {
     /*!
     @brief compare two value_t enum values

single_include/nlohmann/json.hpp

@@ -17163,11 +17163,11 @@ class basic_json
                                  detail::has_non_default_from_json<basic_json_t, ValueType>::value,
                                  int> = 0>
     ValueType get() const noexcept(noexcept(
-                                       JSONSerializer<ValueTypeCV>::from_json(std::declval<const basic_json_t&>())))
+                                       JSONSerializer<ValueType>::from_json(std::declval<const basic_json_t&>())))
     {
         static_assert(not std::is_reference<ValueTypeCV>::value,
                       "get() cannot be used with reference types, you might want to use get_ref()");
-        return JSONSerializer<ValueTypeCV>::from_json(*this);
+        return JSONSerializer<ValueType>::from_json(*this);
     }
 
     /*!