From ca46ef4d256c727a116366334b705ecda0a06c5d Mon Sep 17 00:00:00 2001
From: David Snopek <dsnopek@gmail.com>
Date: Wed, 24 Apr 2024 14:26:06 -0500
Subject: Give compile-time error if registering a class without its own
 `_bind_methods()` function

---
 include/godot_cpp/core/class_db.hpp  |  1 +
 include/godot_cpp/core/type_info.hpp | 10 ++++++++++
 2 files changed, 11 insertions(+)

(limited to 'include/godot_cpp/core')

diff --git a/include/godot_cpp/core/class_db.hpp b/include/godot_cpp/core/class_db.hpp
index 6dedc12..98e9f72 100644
--- a/include/godot_cpp/core/class_db.hpp
+++ b/include/godot_cpp/core/class_db.hpp
@@ -203,6 +203,7 @@ public:
 template <typename T, bool is_abstract>
 void ClassDB::_register_class(bool p_virtual, bool p_exposed, bool p_runtime) {
 	static_assert(TypesAreSame<typename T::self_type, T>::value, "Class not declared properly, please use GDCLASS.");
+	static_assert(!FunctionsAreSame<T::self_type::_bind_methods, T::parent_type::_bind_methods>::value, "Class must declare 'static void _bind_methods'.");
 	static_assert(!std::is_abstract_v<T> || is_abstract, "Class is abstract, please use GDREGISTER_ABSTRACT_CLASS.");
 	instance_binding_callbacks[T::get_class_static()] = &T::_gde_binding_callbacks;
 
diff --git a/include/godot_cpp/core/type_info.hpp b/include/godot_cpp/core/type_info.hpp
index 5896651..096e0ec 100644
--- a/include/godot_cpp/core/type_info.hpp
+++ b/include/godot_cpp/core/type_info.hpp
@@ -58,6 +58,16 @@ struct TypesAreSame<A, A> {
 	static bool const value = true;
 };
 
+template <auto A, auto B>
+struct FunctionsAreSame {
+	static bool const value = false;
+};
+
+template <auto A>
+struct FunctionsAreSame<A, A> {
+	static bool const value = true;
+};
+
 template <typename B, typename D>
 struct TypeInherits {
 	static D *get_d();
-- 
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