Use JSON_HAS_CPP_17 only after it has been defined

Author: remedi

include/nlohmann/detail/conversions/from_json.hpp

@@ -13,14 +13,6 @@
 #include <utility> // pair, declval
 #include <valarray> // valarray
 
-#ifdef JSON_HAS_CPP_17
-    #if __has_include(<optional>)
-        #include <optional>
-    #elif __has_include(<experimental/optional>)
-        #include <experimental/optional>
-    #endif
-#endif
-
 #include <nlohmann/detail/exceptions.hpp>
 #include <nlohmann/detail/macro_scope.hpp>
 #include <nlohmann/detail/meta/cpp_future.hpp>

include/nlohmann/detail/conversions/to_json.hpp

@@ -10,14 +10,6 @@
 #include <valarray> // valarray
 #include <vector> // vector
 
-#ifdef JSON_HAS_CPP_17
-    #if __has_include(<optional>)
-        #include <optional>
-    #elif __has_include(<experimental/optional>)
-        #include <experimental/optional>
-    #endif
-#endif
-
 #include <nlohmann/detail/iterators/iteration_proxy.hpp>
 #include <nlohmann/detail/meta/cpp_future.hpp>
 #include <nlohmann/detail/meta/type_traits.hpp>

include/nlohmann/detail/macro_scope.hpp

@@ -27,6 +27,14 @@
     #define JSON_HAS_CPP_14
 #endif
 
+#ifdef JSON_HAS_CPP_17
+    #if __has_include(<optional>)
+        #include <optional>
+    #elif __has_include(<experimental/optional>)
+        #include <experimental/optional>
+    #endif
+#endif
+
 // disable float-equal warnings on GCC/clang
 #if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
     #pragma GCC diagnostic push

single_include/nlohmann/json.hpp

@@ -69,14 +69,6 @@ SOFTWARE.
 #include <utility> // pair, declval
 #include <valarray> // valarray
 
-#ifdef JSON_HAS_CPP_17
-    #if __has_include(<optional>)
-        #include <optional>
-    #elif __has_include(<experimental/optional>)
-        #include <experimental/optional>
-    #endif
-#endif
-
 // #include <nlohmann/detail/exceptions.hpp>
 
 
@@ -1739,6 +1731,14 @@ JSON_HEDLEY_DIAGNOSTIC_POP
     #define JSON_HAS_CPP_14
 #endif
 
+#ifdef JSON_HAS_CPP_17
+    #if __has_include(<optional>)
+        #include <optional>
+    #elif __has_include(<experimental/optional>)
+        #include <experimental/optional>
+    #endif
+#endif
+
 // disable float-equal warnings on GCC/clang
 #if defined(__clang__) || defined(__GNUC__) || defined(__GNUG__)
     #pragma GCC diagnostic push
@@ -3295,14 +3295,6 @@ constexpr const auto& from_json = detail::static_const<detail::from_json_fn>::va
 #include <valarray> // valarray
 #include <vector> // vector
 
-#ifdef JSON_HAS_CPP_17
-    #if __has_include(<optional>)
-        #include <optional>
-    #elif __has_include(<experimental/optional>)
-        #include <experimental/optional>
-    #endif
-#endif
-
 // #include <nlohmann/detail/iterators/iteration_proxy.hpp>