Replace BIND_VMETHOD by new GDVIRTUAL syntax

* New syntax is type safe.
* New syntax allows for type safe virtuals in native extensions.
* New syntax permits extremely fast calling.

Note: Everything was replaced where possible except for `_gui_input` `_input` and `_unhandled_input`.
These will require API rework on a separate PR as they work different than the rest of the functions.

Added a new method flag METHOD_FLAG_OBJECT_CORE, used internally. Allows to not dump the core virtuals like `_notification` to the json API, since each language will implement those as it is best fits.

5 files changed, 78 insertions, 72 deletions

diff --git a/core/io/resource.cpp b/core/io/resource.cpp
index 0262655927..87b4d7195d 100644
--- a/core/io/resource.cpp
+++ b/core/io/resource.cpp
@@ -352,9 +352,8 @@ Node *Resource::get_local_scene() const {
 }
 
 void Resource::setup_local_to_scene() {
-	if (get_script_instance()) {
-		get_script_instance()->call("_setup_local_to_scene");
-	}
+	// Can't use GDVIRTUAL in Resource, so this will have to be done with a signal
+	emit_signal(SNAME("setup_local_to_scene_requested"));
 }
 
 Node *(*Resource::_get_local_scene_func)() = nullptr;
@@ -422,12 +421,12 @@ void Resource::_bind_methods() {
 
 	ClassDB::bind_method(D_METHOD("duplicate", "subresources"), &Resource::duplicate, DEFVAL(false));
 	ADD_SIGNAL(MethodInfo("changed"));
+	ADD_SIGNAL(MethodInfo("setup_local_to_scene_requested"));
+
 	ADD_GROUP("Resource", "resource_");
 	ADD_PROPERTY(PropertyInfo(Variant::BOOL, "resource_local_to_scene"), "set_local_to_scene", "is_local_to_scene");
 	ADD_PROPERTY(PropertyInfo(Variant::STRING, "resource_path", PROPERTY_HINT_NONE, "", PROPERTY_USAGE_EDITOR), "set_path", "get_path");
 	ADD_PROPERTY(PropertyInfo(Variant::STRING_NAME, "resource_name"), "set_name", "get_name");
-
-	BIND_VMETHOD(MethodInfo("_setup_local_to_scene"));
 }
 
 Resource::Resource() :
diff --git a/core/io/resource_loader.cpp b/core/io/resource_loader.cpp
index d02d827443..64237f3b15 100644
--- a/core/io/resource_loader.cpp
+++ b/core/io/resource_loader.cpp
@@ -68,25 +68,28 @@ bool ResourceFormatLoader::recognize_path(const String &p_path, const String &p_
 }
 
 bool ResourceFormatLoader::handles_type(const String &p_type) const {
-	if (get_script_instance() && get_script_instance()->has_method("_handles_type")) {
-		// I guess custom loaders for custom resources should use "Resource"
-		return get_script_instance()->call("_handles_type", p_type);
+	bool success;
+	if (GDVIRTUAL_CALL(_handles_type, p_type, success)) {
+		return success;
 	}
 
 	return false;
 }
 
 String ResourceFormatLoader::get_resource_type(const String &p_path) const {
-	if (get_script_instance() && get_script_instance()->has_method("_get_resource_type")) {
-		return get_script_instance()->call("_get_resource_type", p_path);
+	String ret;
+
+	if (GDVIRTUAL_CALL(_get_resource_type, p_path, ret)) {
+		return ret;
 	}
 
 	return "";
 }
 
 ResourceUID::ID ResourceFormatLoader::get_resource_uid(const String &p_path) const {
-	if (get_script_instance() && get_script_instance()->has_method("_get_resource_uid")) {
-		return get_script_instance()->call("_get_resource_uid", p_path);
+	int64_t uid;
+	if (GDVIRTUAL_CALL(_get_resource_uid, p_path, uid)) {
+		return uid;
 	}
 
 	return ResourceUID::INVALID_ID;
@@ -105,27 +108,26 @@ void ResourceLoader::get_recognized_extensions_for_type(const String &p_type, Li
 }
 
 bool ResourceFormatLoader::exists(const String &p_path) const {
+	bool success;
+	if (GDVIRTUAL_CALL(_exists, p_path, success)) {
+		return success;
+	}
 	return FileAccess::exists(p_path); //by default just check file
 }
 
 void ResourceFormatLoader::get_recognized_extensions(List<String> *p_extensions) const {
-	if (get_script_instance() && get_script_instance()->has_method("_get_recognized_extensions")) {
-		PackedStringArray exts = get_script_instance()->call("_get_recognized_extensions");
-
-		{
-			const String *r = exts.ptr();
-			for (int i = 0; i < exts.size(); ++i) {
-				p_extensions->push_back(r[i]);
-			}
+	PackedStringArray exts;
+	if (GDVIRTUAL_CALL(_get_recognized_extensions, exts)) {
+		const String *r = exts.ptr();
+		for (int i = 0; i < exts.size(); ++i) {
+			p_extensions->push_back(r[i]);
 		}
 	}
 }
 
 RES ResourceFormatLoader::load(const String &p_path, const String &p_original_path, Error *r_error, bool p_use_sub_threads, float *r_progress, CacheMode p_cache_mode) {
-	// Check user-defined loader if there's any. Hard fail if it returns an error.
-	if (get_script_instance() && get_script_instance()->has_method("_load")) {
-		Variant res = get_script_instance()->call("_load", p_path, p_original_path, p_use_sub_threads, p_cache_mode);
-
+	Variant res;
+	if (GDVIRTUAL_CALL(_load, p_path, p_original_path, p_use_sub_threads, p_cache_mode, res)) {
 		if (res.get_type() == Variant::INT) { // Error code, abort.
 			if (r_error) {
 				*r_error = (Error)res.operator int64_t();
@@ -143,48 +145,42 @@ RES ResourceFormatLoader::load(const String &p_path, const String &p_original_pa
 }
 
 void ResourceFormatLoader::get_dependencies(const String &p_path, List<String> *p_dependencies, bool p_add_types) {
-	if (get_script_instance() && get_script_instance()->has_method("_get_dependencies")) {
-		PackedStringArray deps = get_script_instance()->call("_get_dependencies", p_path, p_add_types);
-
-		{
-			const String *r = deps.ptr();
-			for (int i = 0; i < deps.size(); ++i) {
-				p_dependencies->push_back(r[i]);
-			}
+	PackedStringArray deps;
+	if (GDVIRTUAL_CALL(_get_dependencies, p_path, p_add_types, deps)) {
+		const String *r = deps.ptr();
+		for (int i = 0; i < deps.size(); ++i) {
+			p_dependencies->push_back(r[i]);
 		}
 	}
 }
 
 Error ResourceFormatLoader::rename_dependencies(const String &p_path, const Map<String, String> &p_map) {
-	if (get_script_instance() && get_script_instance()->has_method("_rename_dependencies")) {
-		Dictionary deps_dict;
-		for (Map<String, String>::Element *E = p_map.front(); E; E = E->next()) {
-			deps_dict[E->key()] = E->value();
-		}
+	Dictionary deps_dict;
+	for (Map<String, String>::Element *E = p_map.front(); E; E = E->next()) {
+		deps_dict[E->key()] = E->value();
+	}
 
-		int64_t res = get_script_instance()->call("_rename_dependencies", deps_dict);
-		return (Error)res;
+	int64_t err;
+	if (GDVIRTUAL_CALL(_rename_dependencies, p_path, deps_dict, err)) {
+		return (Error)err;
 	}
 
 	return OK;
 }
 
 void ResourceFormatLoader::_bind_methods() {
-	{
-		MethodInfo info = MethodInfo(Variant::NIL, "_load", PropertyInfo(Variant::STRING, "path"), PropertyInfo(Variant::STRING, "original_path"), PropertyInfo(Variant::BOOL, "use_sub_threads"), PropertyInfo(Variant::INT, "cache_mode"));
-		info.return_val.usage |= PROPERTY_USAGE_NIL_IS_VARIANT;
-		BIND_VMETHOD(info);
-	}
-
-	BIND_VMETHOD(MethodInfo(Variant::PACKED_STRING_ARRAY, "_get_recognized_extensions"));
-	BIND_VMETHOD(MethodInfo(Variant::BOOL, "_handles_type", PropertyInfo(Variant::STRING_NAME, "typename")));
-	BIND_VMETHOD(MethodInfo(Variant::STRING, "_get_resource_type", PropertyInfo(Variant::STRING, "path")));
-	BIND_VMETHOD(MethodInfo("_get_dependencies", PropertyInfo(Variant::STRING, "path"), PropertyInfo(Variant::STRING, "add_types")));
-	BIND_VMETHOD(MethodInfo(Variant::INT, "_rename_dependencies", PropertyInfo(Variant::STRING, "path"), PropertyInfo(Variant::STRING, "renames")));
-
 	BIND_ENUM_CONSTANT(CACHE_MODE_IGNORE);
 	BIND_ENUM_CONSTANT(CACHE_MODE_REUSE);
 	BIND_ENUM_CONSTANT(CACHE_MODE_REPLACE);
+
+	GDVIRTUAL_BIND(_get_recognized_extensions);
+	GDVIRTUAL_BIND(_handles_type, "type");
+	GDVIRTUAL_BIND(_get_resource_type, "path");
+	GDVIRTUAL_BIND(_get_resource_uid, "path");
+	GDVIRTUAL_BIND(_get_dependencies, "path", "add_types");
+	GDVIRTUAL_BIND(_rename_dependencies, "path", "renames");
+	GDVIRTUAL_BIND(_exists, "path");
+	GDVIRTUAL_BIND(_load, "path", "original_path", "use_sub_threads", "cache_mode");
 }
 
 ///////////////////////////////////
diff --git a/core/io/resource_loader.h b/core/io/resource_loader.h
index e525e80a9d..f1d9815635 100644
--- a/core/io/resource_loader.h
+++ b/core/io/resource_loader.h
@@ -32,6 +32,8 @@
 #define RESOURCE_LOADER_H
 
 #include "core/io/resource.h"
+#include "core/object/gdvirtual.gen.inc"
+#include "core/object/script_language.h"
 #include "core/os/semaphore.h"
 #include "core/os/thread.h"
 
@@ -48,6 +50,16 @@ public:
 protected:
 	static void _bind_methods();
 
+	GDVIRTUAL0RC(Vector<String>, _get_recognized_extensions)
+	GDVIRTUAL1RC(bool, _handles_type, StringName)
+	GDVIRTUAL1RC(String, _get_resource_type, String)
+	GDVIRTUAL1RC(ResourceUID::ID, _get_resource_uid, String)
+	GDVIRTUAL2RC(Vector<String>, _get_dependencies, String, bool)
+	GDVIRTUAL2RC(int64_t, _rename_dependencies, String, Dictionary)
+	GDVIRTUAL1RC(bool, _exists, String)
+
+	GDVIRTUAL4RC(Variant, _load, String, String, bool, int)
+
 public:
 	virtual RES load(const String &p_path, const String &p_original_path = "", Error *r_error = nullptr, bool p_use_sub_threads = false, float *r_progress = nullptr, CacheMode p_cache_mode = CACHE_MODE_REUSE);
 	virtual bool exists(const String &p_path) const;
diff --git a/core/io/resource_saver.cpp b/core/io/resource_saver.cpp
index 564de5ee69..823b5f75b1 100644
--- a/core/io/resource_saver.cpp
+++ b/core/io/resource_saver.cpp
@@ -42,44 +42,37 @@ ResourceSavedCallback ResourceSaver::save_callback = nullptr;
 ResourceSaverGetResourceIDForPath ResourceSaver::save_get_id_for_path = nullptr;
 
 Error ResourceFormatSaver::save(const String &p_path, const RES &p_resource, uint32_t p_flags) {
-	if (get_script_instance() && get_script_instance()->has_method("_save")) {
-		return (Error)get_script_instance()->call("_save", p_path, p_resource, p_flags).operator int64_t();
+	int64_t res;
+	if (GDVIRTUAL_CALL(_save, p_path, p_resource, p_flags, res)) {
+		return (Error)res;
 	}
 
 	return ERR_METHOD_NOT_FOUND;
 }
 
 bool ResourceFormatSaver::recognize(const RES &p_resource) const {
-	if (get_script_instance() && get_script_instance()->has_method("_recognize")) {
-		return get_script_instance()->call("_recognize", p_resource);
+	bool success;
+	if (GDVIRTUAL_CALL(_recognize, p_resource, success)) {
+		return success;
 	}
 
 	return false;
 }
 
 void ResourceFormatSaver::get_recognized_extensions(const RES &p_resource, List<String> *p_extensions) const {
-	if (get_script_instance() && get_script_instance()->has_method("_get_recognized_extensions")) {
-		PackedStringArray exts = get_script_instance()->call("_get_recognized_extensions", p_resource);
-
-		{
-			const String *r = exts.ptr();
-			for (int i = 0; i < exts.size(); ++i) {
-				p_extensions->push_back(r[i]);
-			}
+	PackedStringArray exts;
+	if (GDVIRTUAL_CALL(_get_recognized_extensions, p_resource, exts)) {
+		const String *r = exts.ptr();
+		for (int i = 0; i < exts.size(); ++i) {
+			p_extensions->push_back(r[i]);
 		}
 	}
 }
 
 void ResourceFormatSaver::_bind_methods() {
-	{
-		PropertyInfo arg0 = PropertyInfo(Variant::STRING, "path");
-		PropertyInfo arg1 = PropertyInfo(Variant::OBJECT, "resource", PROPERTY_HINT_RESOURCE_TYPE, "Resource");
-		PropertyInfo arg2 = PropertyInfo(Variant::INT, "flags");
-		BIND_VMETHOD(MethodInfo(Variant::INT, "_save", arg0, arg1, arg2));
-	}
-
-	BIND_VMETHOD(MethodInfo(Variant::PACKED_STRING_ARRAY, "_get_recognized_extensions", PropertyInfo(Variant::OBJECT, "resource", PROPERTY_HINT_RESOURCE_TYPE, "Resource")));
-	BIND_VMETHOD(MethodInfo(Variant::BOOL, "_recognize", PropertyInfo(Variant::OBJECT, "resource", PROPERTY_HINT_RESOURCE_TYPE, "Resource")));
+	GDVIRTUAL_BIND(_save, "path", "resource", "flags");
+	GDVIRTUAL_BIND(_recognize, "resource");
+	GDVIRTUAL_BIND(_get_recognized_extensions, "resource");
 }
 
 Error ResourceSaver::save(const String &p_path, const RES &p_resource, uint32_t p_flags) {
diff --git a/core/io/resource_saver.h b/core/io/resource_saver.h
index 2fc8d32126..fcde835dab 100644
--- a/core/io/resource_saver.h
+++ b/core/io/resource_saver.h
@@ -32,6 +32,8 @@
 #define RESOURCE_SAVER_H
 
 #include "core/io/resource.h"
+#include "core/object/gdvirtual.gen.inc"
+#include "core/object/script_language.h"
 
 class ResourceFormatSaver : public RefCounted {
 	GDCLASS(ResourceFormatSaver, RefCounted);
@@ -39,6 +41,10 @@ class ResourceFormatSaver : public RefCounted {
 protected:
 	static void _bind_methods();
 
+	GDVIRTUAL3R(int64_t, _save, String, RES, uint32_t)
+	GDVIRTUAL1RC(bool, _recognize, RES)
+	GDVIRTUAL1RC(Vector<String>, _get_recognized_extensions, RES)
+
 public:
 	virtual Error save(const String &p_path, const RES &p_resource, uint32_t p_flags = 0);
 	virtual bool recognize(const RES &p_resource) const;