fixing issue 2549 (#2567)

* fixing issue 2549

* saving.

tests/builder/builder_string_builder_tests.cpp

@@ -17,6 +17,33 @@ struct Car {
   std::vector<double> tire_pressure;
 }; // Car
 
+
+#if SIMDJSON_SUPPORTS_CONCEPTS
+struct Car2549 {
+	std::string make;
+	std::string model;
+	int64_t year;
+	std::vector<float> tire_pressure;
+};
+namespace simdjson {
+  // we intentionally pass by non-const reference to car.
+	template <typename builder_type>
+	void tag_invoke(serialize_tag, builder_type& builder,  Car2549& car) {
+		builder.start_object();
+		builder.append_key_value("make", car.make);
+		builder.append_comma();
+		builder.append_key_value("model", car.model);
+		builder.append_comma();
+		builder.append_key_value("year", car.year);
+		builder.append_comma();
+		builder.append_key_value("tire_pressure", car.tire_pressure);
+		builder.end_object();
+	}
+} // namespace simdjson
+
+static_assert(simdjson::require_custom_serialization<Car2549>);
+#endif
+
 namespace builder_tests {
 using namespace std;
 
@@ -428,6 +455,21 @@ bool car_test() {
   TEST_SUCCEED();
 }
 #if SIMDJSON_SUPPORTS_CONCEPTS
+
+bool issue2549() {
+  TEST_START();
+  simdjson::builder::string_builder sb;
+	Car2549 c = { "Toyota", "Corolla", 2017, {1.0f,2.0f,3.0f} };
+  sb.start_object();
+  sb.append_key_value("car", c);
+  sb.end_object();
+  std::string_view p;
+  auto result = sb.view().get(p);
+  ASSERT_SUCCESS(result);
+  ASSERT_EQUAL(p, "{\"car\":{\"make\":\"Toyota\",\"model\":\"Corolla\",\"year\":2017,\"tire_pressure\":[1.0,2.0,3.0]}}");
+  TEST_SUCCEED();
+}
+
 bool car_test_template() {
   TEST_START();
   simdjson::builder::string_builder sb;
@@ -616,7 +658,7 @@ bool run() {
 #endif
 #endif
 #if SIMDJSON_SUPPORTS_CONCEPTS
-         car_test_template() && serialize_optional() &&
+         issue2549() && car_test_template() && serialize_optional() &&
 #endif
          append_char() && append_integer() && append_float() && append_null() &&
          clear() && escape_and_append() && escape_and_append_with_quotes() &&

tests/compile_time/compile_time_json_tests.cpp

@@ -661,6 +661,8 @@ bool test_array_of_objects_with_concept() {
     TEST_SUCCEED();
 }
 
+#if defined(__cpp_pp_embed) && __cpp_pp_embed >= 202502L
+#define TEST_EMBED_SUPPORTED
 /**
  * Test: #embed support for external JSON files (C++26)
  */
@@ -688,6 +690,7 @@ bool test_embed_twitter_json() {
 
     TEST_SUCCEED();
 }
+#endif //  defined(__cpp_pp_embed) && __cpp_pp_embed >= 202502L
 
 bool run() {
     return test_basic_object() &&
@@ -713,8 +716,11 @@ bool run() {
            test_user_config_example() &&
            test_nested_servers_example() &&
            test_top_level_array_example() &&
-           test_array_of_objects_with_concept() &&
-           test_embed_twitter_json();
+           test_array_of_objects_with_concept()
+#ifdef TEST_EMBED_SUPPORTED
+           && test_embed_twitter_json()
+#endif
+;
 }
 
 } // namespace compile_time_json_tests