Implement manual class deinitialization.

binding_generator.py

@@ -708,7 +708,7 @@ def generate_builtin_class_header(builtin_api, size, used_classes, fully_used_cl
         result.append("\tfriend class StringName;")
 
     result.append("")
-    result.append("\tstatic struct _MethodBindings {")
+    result.append("\tstatic inline struct _MethodBindings {")
 
     result.append("\t\tGDExtensionTypeFromVariantConstructorFunc from_variant_constructor;")
 
@@ -808,6 +808,9 @@ def generate_builtin_class_header(builtin_api, size, used_classes, fully_used_cl
             else:
                 result.append(f'\tstatic const {correct_type(constant["type"])} {constant["name"]};')
 
+    if builtin_api["has_destructor"]:
+        result.append("\tstatic void deinitialize();")
+
     if builtin_api["has_destructor"]:
         result.append(f"\t~{class_name}();")
 
@@ -1091,13 +1094,14 @@ def generate_builtin_class_source(builtin_api, size, used_classes, fully_used_cl
         result.append("")
 
     result.append("#include <godot_cpp/core/builtin_ptrcall.hpp>")
+    if builtin_api["has_destructor"]:
+        result.append("#include <godot_cpp/core/class_db.hpp>")
     result.append("")
     result.append("#include <utility>")
     result.append("")
     result.append("namespace godot {")
     result.append("")
 
-    result.append(f"{class_name}::_MethodBindings {class_name}::_method_bindings;")
     result.append("")
 
     result.append(f"void {class_name}::_init_bindings_constructors_destructor() {{")
@@ -1117,6 +1121,9 @@ def generate_builtin_class_source(builtin_api, size, used_classes, fully_used_cl
             f"\t_method_bindings.destructor = internal::gdextension_interface_variant_get_ptr_destructor({enum_type_name});"
         )
 
+    if builtin_api["has_destructor"]:
+        result.append("\tClassDB::register_class_deinitialization_function(deinitialize);")
+
     result.append("}")
 
     result.append(f"void {class_name}::init_bindings() {{")
@@ -1237,9 +1244,16 @@ def generate_builtin_class_source(builtin_api, size, used_classes, fully_used_cl
     result.append("}")
     result.append("")
 
+    if builtin_api["has_destructor"]:
+        result.append(f"void {class_name}::deinitialize() {{")
+        result.append("\tmemset(&_method_bindings, 0, sizeof(_MethodBindings));")
+        result.append("}")
+        result.append("")
+
     if builtin_api["has_destructor"]:
         result.append(f"{class_name}::~{class_name}() {{")
-        result.append("\t_method_bindings.destructor(&opaque);")
+        result.append("\tif (_method_bindings.destructor)")
+        result.append("\t\t_method_bindings.destructor(&opaque);")
         result.append("}")
         result.append("")
 

include/godot_cpp/core/class_db.hpp

@@ -44,6 +44,7 @@
 // Needs to come after method_bind and object have been included.
 #include <godot_cpp/variant/callable_method_pointer.hpp>
 
+#include <functional>
 #include <list>
 #include <mutex>
 #include <set>
@@ -107,6 +108,7 @@ class ClassDB {
 	static std::vector<StringName> class_register_order;
 	static std::unordered_map<StringName, Object *> engine_singletons;
 	static std::mutex engine_singletons_mutex;
+	static std::vector<std::function<void(void)>> class_deinitialization_functions;
 
 	static MethodBind *bind_methodfi(uint32_t p_flags, MethodBind *p_bind, const MethodDefinition &method_name, const void **p_defs, int p_defcount);
 	static void initialize_class(const ClassInfo &cl);
@@ -166,6 +168,10 @@ class ClassDB {
 		engine_singletons[p_class_name] = p_singleton;
 	}
 
+	static void register_class_deinitialization_function(std::function<void(void)> p_deinit_function) {
+		class_deinitialization_functions.push_back(p_deinit_function);
+	}
+
 	static void _unregister_engine_singleton(const StringName &p_class_name) {
 		std::lock_guard<std::mutex> lock(engine_singletons_mutex);
 		engine_singletons.erase(p_class_name);

src/core/class_db.cpp

@@ -46,6 +46,7 @@ std::vector<StringName> ClassDB::class_register_order;
 std::unordered_map<StringName, Object *> ClassDB::engine_singletons;
 std::mutex ClassDB::engine_singletons_mutex;
 GDExtensionInitializationLevel ClassDB::current_level = GDEXTENSION_INITIALIZATION_CORE;
+std::vector<std::function<void(void)>> ClassDB::class_deinitialization_functions;
 
 MethodDefinition D_METHOD(StringName p_name) {
 	return MethodDefinition(p_name);
@@ -436,6 +437,9 @@ void ClassDB::deinitialize(GDExtensionInitializationLevel p_level) {
 		for (std::vector<Object *>::iterator i = singleton_objects.begin(); i != singleton_objects.end(); i++) {
 			internal::gdextension_interface_object_free_instance_binding((*i)->_owner, internal::token);
 		}
+		for (std::vector<std::function<void(void)>>::reverse_iterator i = class_deinitialization_functions.rbegin(); i != class_deinitialization_functions.rend(); i++) {
+			(*i)();
+		}
 	}
 }