From d7a885cea82b39be21b0f847e83cb78e117ff6ca Mon Sep 17 00:00:00 2001
From: "Jeong, YunWon" <69878+youknowone@users.noreply.github.com>
Date: Mon, 19 Jan 2026 16:43:20 +0900
Subject: [PATCH] sys._clear_type_descriptors (#6795)

---
 crates/vm/src/stdlib/sys.rs | 26 ++++++++++++++++++++++++++
 crates/vm/src/vm/context.rs |  1 +
 2 files changed, 27 insertions(+)

diff --git a/crates/vm/src/stdlib/sys.rs b/crates/vm/src/stdlib/sys.rs
index 305e1cfa6..6c8a4e406 100644
--- a/crates/vm/src/stdlib/sys.rs
+++ b/crates/vm/src/stdlib/sys.rs
@@ -1215,6 +1215,32 @@ mod sys {
         crate::vm::thread::COROUTINE_ORIGIN_TRACKING_DEPTH.get() as i32
     }
 
+    #[pyfunction]
+    fn _clear_type_descriptors(type_obj: PyTypeRef, vm: &VirtualMachine) -> PyResult<()> {
+        use crate::types::PyTypeFlags;
+
+        // Check if type is immutable
+        if type_obj.slots.flags.has_feature(PyTypeFlags::IMMUTABLETYPE) {
+            return Err(vm.new_type_error("argument is immutable".to_owned()));
+        }
+
+        let mut attributes = type_obj.attributes.write();
+
+        // Remove __dict__ descriptor if present
+        attributes.swap_remove(identifier!(vm, __dict__));
+
+        // Remove __weakref__ descriptor if present
+        attributes.swap_remove(identifier!(vm, __weakref__));
+
+        drop(attributes);
+
+        // Update slots to notify subclasses and recalculate cached values
+        type_obj.update_slot::<true>(identifier!(vm, __dict__), &vm.ctx);
+        type_obj.update_slot::<true>(identifier!(vm, __weakref__), &vm.ctx);
+
+        Ok(())
+    }
+
     #[pyfunction]
     fn getswitchinterval(vm: &VirtualMachine) -> f64 {
         // Return the stored switch interval
diff --git a/crates/vm/src/vm/context.rs b/crates/vm/src/vm/context.rs
index 9978554bc..f4368e91a 100644
--- a/crates/vm/src/vm/context.rs
+++ b/crates/vm/src/vm/context.rs
@@ -234,6 +234,7 @@ declare_const_name! {
     __typing_is_unpacked_typevartuple__,
     __typing_prepare_subst__,
     __typing_unpacked_tuple_args__,
+    __weakref__,
     __xor__,
 
     // common names