From 084725e2b36675165f196e77156bf3ae5a650dd2 Mon Sep 17 00:00:00 2001
From: blueloveTH <blueloveTH@foxmail.com>
Date: Sat, 29 Apr 2023 14:36:09 +0800
Subject: [PATCH] ...

---
 src/iter.h | 11 ++---------
 src/obj.h  | 11 ++++++++---
 src/vm.h   |  2 +-
 3 files changed, 11 insertions(+), 13 deletions(-)

diff --git a/src/iter.h b/src/iter.h
index 94c59548..efa642a1 100644
--- a/src/iter.h
+++ b/src/iter.h
@@ -41,7 +41,7 @@ public:
         return array->operator[](index++);
     }
 
-    void _gc_mark() const override {
+    void _gc_mark() const{
         OBJ_MARK(ref);
     }
 };
@@ -60,7 +60,7 @@ public:
         return VAR(str->u8_getitem(index++));
     }
 
-    void _gc_mark() const override {
+    void _gc_mark() const{
         OBJ_MARK(ref);
     }
 };
@@ -95,11 +95,4 @@ inline void Generator::_gc_mark() const{
     for(PyObject* obj: s_backup) OBJ_MARK(obj);
 }
 
-template<typename T>
-void gc_mark(T& t) {
-    if constexpr(std::is_base_of_v<BaseIter, T>){
-        t._gc_mark();
-    }
-}
-
 } // namespace pkpy
\ No newline at end of file
diff --git a/src/obj.h b/src/obj.h
index ffcf2ba7..5dd9ffab 100644
--- a/src/obj.h
+++ b/src/obj.h
@@ -93,7 +93,6 @@ protected:
     VM* vm;
 public:
     BaseIter(VM* vm) : vm(vm) {}
-    virtual void _gc_mark() const {}
     virtual PyObject* next() = 0;
     virtual ~BaseIter() = default;
 };
@@ -128,11 +127,18 @@ struct PyObject{
     }
 };
 
+template <typename, typename=void> struct has_gc_marker : std::false_type {};
+template <typename T> struct has_gc_marker<T, std::void_t<decltype(&T::_gc_mark)>> : std::true_type {};
+
 template <typename T>
 struct Py_ final: PyObject {
     T _value;
     void* value() override { return &_value; }
-    void _obj_gc_mark() override {}
+    void _obj_gc_mark() override {
+        if constexpr (has_gc_marker<T>::value) {
+            _value._gc_mark();
+        }
+    }
     Py_(Type type, const T& value) : PyObject(type), _value(value) {}
     Py_(Type type, T&& value) : PyObject(type), _value(std::move(value)) {}
 };
@@ -140,7 +146,6 @@ struct Py_ final: PyObject {
 struct MappingProxy{
     PyObject* obj;
     MappingProxy(PyObject* obj) : obj(obj) {}
-
     NameDict& attr() noexcept { return obj->attr(); }
 };
 
diff --git a/src/vm.h b/src/vm.h
index b360d941..c4ce61d0 100644
--- a/src/vm.h
+++ b/src/vm.h
@@ -55,7 +55,7 @@ public:
     }
 
     PyObject* next() override;
-    void _gc_mark() const override;
+    void _gc_mark() const;
 };
 
 struct PyTypeInfo{