From 0f371bb4382d6e0702c0101c5a7bce50c3eb1fb8 Mon Sep 17 00:00:00 2001
From: Moreal <dev.moreal@gmail.com>
Date: Sat, 13 Apr 2024 02:13:39 +0900
Subject: [PATCH 1/3] Allow update `__class__` for module subclasses

---
 vm/src/builtins/object.rs | 17 +++++++++++++++--
 1 file changed, 15 insertions(+), 2 deletions(-)

diff --git a/vm/src/builtins/object.rs b/vm/src/builtins/object.rs
index fca68a9f34..1fbebf2729 100644
--- a/vm/src/builtins/object.rs
+++ b/vm/src/builtins/object.rs
@@ -1,5 +1,6 @@
 use super::{PyDictRef, PyList, PyStr, PyStrRef, PyType, PyTypeRef};
 use crate::common::hash::PyHash;
+use crate::types::PyTypeFlags;
 use crate::{
     class::PyClassImpl,
     function::{Either, FuncArgs, PyArithmeticValue, PyComparisonValue, PySetterValue},
@@ -281,7 +282,18 @@ impl PyBaseObject {
 
     #[pygetset(name = "__class__", setter)]
     fn set_class(instance: PyObjectRef, value: PyObjectRef, vm: &VirtualMachine) -> PyResult<()> {
-        if instance.payload_is::<PyBaseObject>() {
+        let both_module = instance.class().fast_issubclass(vm.ctx.types.module_type)
+            && value.class().fast_issubclass(vm.ctx.types.module_type);
+        let both_mutable = !instance
+            .class()
+            .slots
+            .flags
+            .has_feature(PyTypeFlags::IMMUTABLETYPE)
+            && !value
+                .downcast_ref::<PyType>()
+                .map(|t| t.slots.flags.has_feature(PyTypeFlags::IMMUTABLETYPE))
+                .unwrap_or(false);
+        if both_mutable || both_module {
             match value.downcast::<PyType>() {
                 Ok(cls) => {
                     // FIXME(#1979) cls instances might have a payload
@@ -298,7 +310,8 @@ impl PyBaseObject {
             }
         } else {
             Err(vm.new_type_error(
-                "__class__ assignment only supported for types without a payload".to_owned(),
+                "__class__ assignment only supported for mutable types or ModuleType subclasses"
+                    .to_owned(),
             ))
         }
     }

From 42fafcfdbe6ca0ad54b3a82284e155078c9d57c1 Mon Sep 17 00:00:00 2001
From: Moreal <dev.moreal@gmail.com>
Date: Sat, 13 Apr 2024 18:50:04 +0900
Subject: [PATCH 2/3] Set `IMMUTABLETYPE` flag for static classes

---
 derive-impl/src/pyclass.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/derive-impl/src/pyclass.rs b/derive-impl/src/pyclass.rs
index 8f688b366a..a8371d889b 100644
--- a/derive-impl/src/pyclass.rs
+++ b/derive-impl/src/pyclass.rs
@@ -1497,6 +1497,9 @@ fn extract_impl_attrs(attr: AttributeArgs, item: &Ident) -> Result<ExtractedImpl
                              .union(::rustpython_vm::types::PyTypeFlags::#ident)
                         });
                     }
+                    flags.push(quote! {
+                        .union(::rustpython_vm::types::PyTypeFlags::IMMUTABLETYPE)
+                    });
                 } else {
                     bail_span!(path, "Unknown pyimpl attribute")
                 }

From 31f1d6402fe200fca6bee361cb16643a4ba606e7 Mon Sep 17 00:00:00 2001
From: Moreal <dev.moreal@gmail.com>
Date: Sun, 14 Apr 2024 11:47:44 +0900
Subject: [PATCH 3/3] Unmark fixed tests

---
 Lib/test/test_opcache.py | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/Lib/test/test_opcache.py b/Lib/test/test_opcache.py
index 978cc93053..8f1f8764b1 100644
--- a/Lib/test/test_opcache.py
+++ b/Lib/test/test_opcache.py
@@ -152,8 +152,6 @@ def f():
         for _ in range(1025):
             self.assertTrue(f())
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_metaclass_swap(self):
         class OldMetaclass(type):
             @property
@@ -411,8 +409,6 @@ def f():
         for _ in range(1025):
             self.assertTrue(f())
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_metaclass_swap(self):
         class OldMetaclass(type):
             @property