Avoid creating objects that Godot is going to use placement new to initialize

Author: dsnopek

binding_generator.py

@@ -454,6 +454,8 @@ def generate_builtin_class_header(builtin_api, size, used_classes, fully_used_cl
     result.append("")
     result.append("\tstatic struct _MethodBindings {")
 
+    result.append(f'\t\tGDExtensionTypeFromVariantConstructorFunc from_variant_constructor;')
+
     if "constructors" in builtin_api:
         for constructor in builtin_api["constructors"]:
             result.append(f'\t\tGDExtensionPtrConstructor constructor_{constructor["index"]};')
@@ -494,6 +496,9 @@ def generate_builtin_class_header(builtin_api, size, used_classes, fully_used_cl
     result.append("\tstatic void init_bindings();")
     result.append("\tstatic void _init_bindings_constructors_destructor();")
 
+    result.append("")
+    result.append(f"\t{class_name}(const Variant *p_variant);")
+
     result.append("")
     result.append("public:")
 
@@ -818,6 +823,8 @@ def generate_builtin_class_source(builtin_api, size, used_classes, fully_used_cl
 
     result.append(f"void {class_name}::_init_bindings_constructors_destructor() {{")
 
+    result.append(f'\t_method_bindings.from_variant_constructor = internal::gdextension_interface_get_variant_to_type_constructor({enum_type_name});')
+
     if "constructors" in builtin_api:
         for constructor in builtin_api["constructors"]:
             result.append(
@@ -899,6 +906,11 @@ def generate_builtin_class_source(builtin_api, size, used_classes, fully_used_cl
 
     copy_constructor_index = -1
 
+    result.append(f"{class_name}::{class_name}(const Variant *p_variant) {{")
+    result.append("\t_method_bindings.from_variant_constructor(&opaque, this->_native_ptr());")
+    result.append("}");
+    result.append("");
+
     if "constructors" in builtin_api:
         for constructor in builtin_api["constructors"]:
             method_signature = f"{class_name}::{class_name}("

include/godot_cpp/variant/variant.hpp

@@ -47,8 +47,6 @@ class ObjectID;
 class Variant {
 	uint8_t opaque[GODOT_CPP_VARIANT_SIZE]{ 0 };
 
-	_FORCE_INLINE_ GDExtensionVariantPtr _native_ptr() const { return const_cast<uint8_t(*)[GODOT_CPP_VARIANT_SIZE]>(&opaque); }
-
 	friend class GDExtensionBinding;
 	friend class MethodBind;
 
@@ -145,6 +143,7 @@ class Variant {
 	static GDExtensionTypeFromVariantConstructorFunc to_type_constructor[VARIANT_MAX];
 
 public:
+	_FORCE_INLINE_ GDExtensionVariantPtr _native_ptr() const { return const_cast<uint8_t(*)[GODOT_CPP_VARIANT_SIZE]>(&opaque); }
 	Variant();
 	Variant(std::nullptr_t n) :
 			Variant() {}

src/variant/variant.cpp

@@ -459,15 +459,11 @@ Variant::operator Signal() const {
 }
 
 Variant::operator Dictionary() const {
-	Dictionary result;
-	to_type_constructor[DICTIONARY](result._native_ptr(), _native_ptr());
-	return result;
+	return Dictionary(this);
 }
 
 Variant::operator Array() const {
-	Array result;
-	to_type_constructor[ARRAY](result._native_ptr(), _native_ptr());
-	return result;
+	return Array(this);
 }
 
 Variant::operator PackedByteArray() const {