Make extension instances create the corresponding godot object in their constructor

SConstruct

@@ -458,6 +458,7 @@ if should_generate_bindings:
 # Sources to compile
 sources = []
 add_sources(sources, "src", "cpp")
+add_sources(sources, "src/classes", "cpp")
 add_sources(sources, "src/core", "cpp")
 add_sources(sources, "src/variant", "cpp")
 add_sources(sources, "gen/src/variant", "cpp")

binding_generator.py

@@ -914,9 +914,6 @@ def generate_engine_class_header(class_api, used_classes, fully_used_classes, us
     result.append("")
 
     result.append("public:")
-
-    # Constructor override, since parent Wrapped has protected constructor.
-    result.append(f"\t{class_name}() = default;")
     result.append("")
 
     if "enums" in class_api:

include/godot_cpp/core/class_db.hpp

@@ -158,9 +158,8 @@ void ClassDB::register_class() {
 		nullptr, // GDNativeExtensionClassUnreference
 		T::create, // GDNativeExtensionClassCreateInstance create_instance_func; /* this one is mandatory */
 		T::free, // GDNativeExtensionClassFreeInstance free_instance_func; /* this one is mandatory */
-		T::set_object_instance, // GDNativeExtensionClassObjectInstance object_instance_func; /* this one is mandatory */
 		&ClassDB::get_virtual_func, // GDNativeExtensionClassGetVirtual get_virtual_func;
-		(void *)cl.name, //void *class_userdata;
+		(void *)cl.name, // void *class_userdata;
 	};
 
 	internal::gdn_interface->classdb_register_extension_class(internal::library, cl.name, cl.parent_name, &class_info);

include/godot_cpp/core/memory.hpp

@@ -68,16 +68,17 @@ class Memory {
 	static void free_static(void *p_ptr);
 };
 
-#define memnew(m_v)                                                           \
-	([&]() {                                                                  \
-		if constexpr (std::is_base_of<godot::Object, decltype(m_v)>::value) { \
-			return godot::internal::Creator<decltype(m_v)>::_new();           \
-		} else {                                                              \
-			return new ("") m_v;                                              \
-		}                                                                     \
-	}())
-
-#define memnew_placement(m_placement, m_class) (new (m_placement, sizeof(m_class), "") m_class)
+_ALWAYS_INLINE_ void postinitialize_handler(void *) {}
+
+template <class T>
+_ALWAYS_INLINE_ T *_post_initialize(T *p_obj) {
+	postinitialize_handler(p_obj);
+	return p_obj;
+}
+
+#define memnew(m_class) _post_initialize(new ("") m_class)
+
+#define memnew_placement(m_placement, m_class) _post_initialize(new (m_placement, sizeof(m_class), "") m_class)
 
 template <class T>
 void memdelete(T *p_class, typename std::enable_if<!std::is_base_of_v<godot::Wrapped, T>>::type * = 0) {

include/godot_cpp/godot.hpp

@@ -55,9 +55,6 @@ class GDExtensionBinding {
 	static void initialize_level(void *userdata, GDNativeInitializationLevel p_level);
 	static void deinitialize_level(void *userdata, GDNativeInitializationLevel p_level);
 
-	static void *create_instance_callback(void *p_token, void *p_instance);
-	static void free_instance_callback(void *p_token, void *p_instance, void *p_binding);
-
 	class InitObject {
 		const GDNativeInterface *gdn_interface;
 		const GDNativeExtensionClassLibraryPtr library;

src/classes/wrapped.cpp

@@ -0,0 +1,56 @@
+/*************************************************************************/
+/*  wrapped.cpp                                                          */
+/*************************************************************************/
+/*                       This file is part of:                           */
+/*                           GODOT ENGINE                                */
+/*                      https://godotengine.org                          */
+/*************************************************************************/
+/* Copyright (c) 2007-2021 Juan Linietsky, Ariel Manzur.                 */
+/* Copyright (c) 2014-2021 Godot Engine contributors (cf. AUTHORS.md).   */
+/*                                                                       */
+/* Permission is hereby granted, free of charge, to any person obtaining */
+/* a copy of this software and associated documentation files (the       */
+/* "Software"), to deal in the Software without restriction, including   */
+/* without limitation the rights to use, copy, modify, merge, publish,   */
+/* distribute, sublicense, and/or sell copies of the Software, and to    */
+/* permit persons to whom the Software is furnished to do so, subject to */
+/* the following conditions:                                             */
+/*                                                                       */
+/* The above copyright notice and this permission notice shall be        */
+/* included in all copies or substantial portions of the Software.       */
+/*                                                                       */
+/* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,       */
+/* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF    */
+/* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.*/
+/* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY  */
+/* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,  */
+/* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE     */
+/* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                */
+/*************************************************************************/
+
+#include <godot_cpp/classes/wrapped.hpp>
+
+#include <godot_cpp/variant/builtin_types.hpp>
+
+#include <godot_cpp/classes/object.hpp>
+
+namespace godot {
+
+void Wrapped::_postinitialize() {
+	godot::internal::gdn_interface->object_set_instance(_owner, _get_class(), this);
+	godot::internal::gdn_interface->object_set_instance_binding(_owner, godot::internal::token, this, _get_bindings_callbacks());
+}
+
+Wrapped::Wrapped(const char *p_godot_class) {
+	_owner = godot::internal::gdn_interface->classdb_construct_object(p_godot_class);
+}
+
+Wrapped::Wrapped(GodotObject *p_godot_object) {
+	_owner = p_godot_object;
+}
+
+void postinitialize_handler(Wrapped *p_wrapped) {
+	p_wrapped->_postinitialize();
+}
+
+} // namespace godot

src/godot.cpp

@@ -91,17 +91,6 @@ void GDExtensionBinding::deinitialize_level(void *userdata, GDNativeInitializati
 	}
 }
 
-void *GDExtensionBinding::create_instance_callback(void *p_token, void *p_instance) {
-	ERR_FAIL_COND_V_MSG(p_token != internal::library, nullptr, "Asking for creating instance with invalid token.");
-	Wrapped *wrapped = memnew(Wrapped(p_instance));
-	return wrapped;
-}
-
-void GDExtensionBinding::free_instance_callback(void *p_token, void *p_instance, void *p_binding) {
-	ERR_FAIL_COND_MSG(p_token != internal::library, "Asking for freeing instance with invalid token.");
-	memdelete((Wrapped *)p_binding);
-}
-
 void GDExtensionBinding::InitObject::register_core_initializer(Callback p_core_init) const {
 	GDExtensionBinding::init_callbacks[GDNATIVE_INITIALIZATION_CORE] = p_core_init;
 }