fix additionalProperties defaulting to false, add test

Author: gg-sr

include/rfl/json/schema/Type.hpp

@@ -101,7 +101,8 @@ struct Type {
     rfl::Flatten<Annotations> annotations{};
     rfl::Object<Type> properties{};
     std::vector<std::string> required{};
-    rfl::Variant<bool, std::shared_ptr<Type>> additionalProperties{};
+    std::optional<rfl::Variant<std::shared_ptr<Type>, bool>>
+        additionalProperties{};
   };
 
   struct OneOf {

include/rfl/parsing/schema/Type.hpp

@@ -79,7 +79,7 @@ struct RFL_API Type {
 
   struct Object {
     rfl::Object<Type> types_;
-    rfl::Variant<bool, std::shared_ptr<Type>> additional_properties_;
+    rfl::Variant<std::shared_ptr<Type>, bool> additional_properties_;
   };
 
   /// All values are assumed to be required unless explicitly stated otherwise

src/rfl/json/to_schema.cpp

@@ -287,14 +287,17 @@ schema::Type type_to_json_schema_type(const parsing::schema::Type& _type,
       }
       auto additional_properties = rfl::visit(
           [&](const auto& _a)
-              -> rfl::Variant<bool, std::shared_ptr<schema::Type>> {
+              -> std::optional<
+                  rfl::Variant<std::shared_ptr<schema::Type>, bool>> {
             using A = std::remove_cvref_t<decltype(_a)>;
             if constexpr (std::is_same<A, bool>()) {
               return _a;
             } else {
-              return _a ? std::make_shared<schema::Type>(
-                              type_to_json_schema_type(*_a, _no_required))
-                        : std::shared_ptr<schema::Type>();
+              if (!_a) {
+                return std::nullopt;
+              }
+              return std::make_shared<schema::Type>(
+                  type_to_json_schema_type(*_a, _no_required));
             }
           },
           _t.additional_properties_);

tests/json/test_json_schema8.cpp

@@ -0,0 +1,35 @@
+#include <optional>
+#include <rfl.hpp>
+#include <rfl/json.hpp>
+#include <string>
+
+namespace test_json_schema8 {
+
+struct Address {
+  std::string street;
+  int number;
+};
+
+struct Person {
+  std::string name;
+  Address address;  // Ensures that nested objects also get
+                    // `additionalProperties: false`.
+  std::optional<int> age;
+};
+
+TEST(json, test_json_schema8) {
+  const auto json_schema = rfl::json::to_schema<Person, rfl::NoExtraFields>();
+
+  EXPECT_EQ(
+      json_schema,
+      R"({"$schema":"https://json-schema.org/draft/2020-12/schema","$ref":"#/$defs/test_json_schema8__Person","$defs":{"test_json_schema8__Address":{"type":"object","properties":{"street":{"type":"string"},"number":{"type":"integer"}},"required":["street","number"],"additionalProperties":false},"test_json_schema8__Person":{"type":"object","properties":{"name":{"type":"string"},"address":{"$ref":"#/$defs/test_json_schema8__Address"},"age":{"anyOf":[{"type":"integer"},{"type":"null"}]}},"required":["name","address"],"additionalProperties":false}}})");
+}
+
+TEST(json, test_json_schema8_without_no_extra_fields) {
+  const auto json_schema = rfl::json::to_schema<Person>();
+
+  EXPECT_EQ(
+      json_schema,
+      R"({"$schema":"https://json-schema.org/draft/2020-12/schema","$ref":"#/$defs/test_json_schema8__Person","$defs":{"test_json_schema8__Address":{"type":"object","properties":{"street":{"type":"string"},"number":{"type":"integer"}},"required":["street","number"]},"test_json_schema8__Person":{"type":"object","properties":{"name":{"type":"string"},"address":{"$ref":"#/$defs/test_json_schema8__Address"},"age":{"anyOf":[{"type":"integer"},{"type":"null"}]}},"required":["name","address"]}}})");
+}
+}  // namespace test_json_schema8