Implement native extension system

* Deprecates GDNative in favor of a simpler, lower level interface.
* New extension system allows registering core engine classes.
* Simple header interface in gdnative_interace.h

core/SCsub

@@ -186,6 +186,7 @@ SConscript("io/SCsub")
 SConscript("debugger/SCsub")
 SConscript("input/SCsub")
 SConscript("variant/SCsub")
+SConscript("extension/SCsub")
 SConscript("object/SCsub")
 SConscript("templates/SCsub")
 SConscript("string/SCsub")

core/config/engine.cpp

@@ -236,9 +236,10 @@ Engine::Engine() {
 	singleton = this;
 }
 
-Engine::Singleton::Singleton(const StringName &p_name, Object *p_ptr) :
+Engine::Singleton::Singleton(const StringName &p_name, Object *p_ptr, const StringName &p_class_name) :
 		name(p_name),
-		ptr(p_ptr) {
+		ptr(p_ptr),
+		class_name(p_class_name) {
 #ifdef DEBUG_ENABLED
 	RefCounted *rc = Object::cast_to<RefCounted>(p_ptr);
 	if (rc && !rc->is_referenced()) {

core/config/engine.h

@@ -41,7 +41,8 @@ class Engine {
 	struct Singleton {
 		StringName name;
 		Object *ptr;
-		Singleton(const StringName &p_name = StringName(), Object *p_ptr = nullptr);
+		StringName class_name; //used for binding generation hinting
+		Singleton(const StringName &p_name = StringName(), Object *p_ptr = nullptr, const StringName &p_class_name = StringName());
 	};
 
 private:

core/extension/SCsub

@@ -0,0 +1,7 @@
+#!/usr/bin/env python
+
+Import("env")
+
+env_extension = env.Clone()
+
+env_extension.add_source_files(env.core_sources, "*.cpp")

core/extension/extension_api_dump.h

@@ -0,0 +1,45 @@
+/*************************************************************************/
+/*  extension_api_dump.h                                                 */
+/*************************************************************************/
+/*                       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.                */
+/*************************************************************************/
+
+#ifndef API_DUMP_H
+#define API_DUMP_H
+
+#include "core/extension/native_extension.h"
+
+#ifdef TOOLS_ENABLED
+
+class NativeExtensionAPIDump {
+public:
+	static Dictionary generate_extension_api();
+	static void generate_extension_json_file(const String &p_path);
+};
+#endif
+
+#endif // API_DUMP_H