split PyCell and PyClassObject concepts

src/impl_/coroutine.rs

@@ -1,12 +1,12 @@
 use std::{
     future::Future,
-    mem,
     ops::{Deref, DerefMut},
 };
 
 use crate::{
     coroutine::{cancel::ThrowCallback, Coroutine},
     instance::Bound,
+    pycell::impl_::PyClassBorrowChecker,
     pyclass::boolean_struct::False,
     types::PyString,
     IntoPy, Py, PyAny, PyCell, PyClass, PyErr, PyObject, PyResult, Python,
@@ -40,9 +40,9 @@ pub struct RefGuard<T: PyClass>(Py<T>);
 
 impl<T: PyClass> RefGuard<T> {
     pub fn new(obj: &PyAny) -> PyResult<Self> {
-        let owned: Py<T> = obj.extract()?;
-        mem::forget(owned.try_borrow(obj.py())?);
-        Ok(RefGuard(owned))
+        let owned: Bound<'_, T> = obj.extract()?;
+        owned.get_class_object().borrow_checker().try_borrow()?;
+        Ok(RefGuard(owned.unbind()))
     }
 }
 
@@ -57,9 +57,11 @@ impl<T: PyClass> Deref for RefGuard<T> {
 impl<T: PyClass> Drop for RefGuard<T> {
     fn drop(&mut self) {
         Python::with_gil(|gil| {
-            #[allow(deprecated)]
-            let self_ref = self.0.bind(gil);
-            self_ref.release_ref()
+            self.0
+                .bind(gil)
+                .get_class_object()
+                .borrow_checker()
+                .release_borrow()
         })
     }
 }
@@ -68,9 +70,9 @@ pub struct RefMutGuard<T: PyClass<Frozen = False>>(Py<T>);
 
 impl<T: PyClass<Frozen = False>> RefMutGuard<T> {
     pub fn new(obj: &PyAny) -> PyResult<Self> {
-        let owned: Py<T> = obj.extract()?;
-        mem::forget(owned.try_borrow_mut(obj.py())?);
-        Ok(RefMutGuard(owned))
+        let owned: Bound<'_, T> = obj.extract()?;
+        owned.get_class_object().borrow_checker().try_borrow_mut()?;
+        Ok(RefMutGuard(owned.unbind()))
     }
 }
 
@@ -92,9 +94,11 @@ impl<T: PyClass<Frozen = False>> DerefMut for RefMutGuard<T> {
 impl<T: PyClass<Frozen = False>> Drop for RefMutGuard<T> {
     fn drop(&mut self) {
         Python::with_gil(|gil| {
-            #[allow(deprecated)]
-            let self_ref = self.0.bind(gil);
-            self_ref.release_mut()
+            self.0
+                .bind(gil)
+                .get_class_object()
+                .borrow_checker()
+                .release_borrow_mut()
         })
     }
 }

src/impl_/pycell.rs

@@ -1,2 +1,4 @@
 //! Externally-accessible implementation of pycell
-pub use crate::pycell::impl_::{GetBorrowChecker, PyClassMutability};
+pub use crate::pycell::impl_::{
+    GetBorrowChecker, PyClassMutability, PyClassObject, PyClassObjectBase, PyClassObjectLayout,
+};

src/impl_/pyclass.rs

@@ -2,9 +2,8 @@ use crate::{
     exceptions::{PyAttributeError, PyNotImplementedError, PyRuntimeError, PyValueError},
     ffi,
     impl_::freelist::FreeList,
-    impl_::pycell::{GetBorrowChecker, PyClassMutability},
+    impl_::pycell::{GetBorrowChecker, PyClassMutability, PyClassObjectLayout},
     internal_tricks::extract_c_string,
-    pycell::PyCellLayout,
     pyclass_init::PyObjectInit,
     types::any::PyAnyMethods,
     types::PyBool,
@@ -883,6 +882,8 @@ macro_rules! generate_pyclass_richcompare_slot {
 }
 pub use generate_pyclass_richcompare_slot;
 
+use super::pycell::PyClassObject;
+
 /// Implements a freelist.
 ///
 /// Do not implement this trait manually. Instead, use `#[pyclass(freelist = N)]`
@@ -1095,7 +1096,7 @@ impl<T> PyClassThreadChecker<T> for ThreadCheckerImpl {
 
 /// Trait denoting that this class is suitable to be used as a base type for PyClass.
 pub trait PyClassBaseType: Sized {
-    type LayoutAsBase: PyCellLayout<Self>;
+    type LayoutAsBase: PyClassObjectLayout<Self>;
     type BaseNativeType;
     type Initializer: PyObjectInit<Self>;
     type PyClassMutability: PyClassMutability;
@@ -1105,15 +1106,15 @@ pub trait PyClassBaseType: Sized {
 ///
 /// In the future this will be extended to immutable PyClasses too.
 impl<T: PyClass> PyClassBaseType for T {
-    type LayoutAsBase = crate::pycell::PyCell<T>;
+    type LayoutAsBase = crate::impl_::pycell::PyClassObject<T>;
     type BaseNativeType = T::BaseNativeType;
     type Initializer = crate::pyclass_init::PyClassInitializer<Self>;
     type PyClassMutability = T::PyClassMutability;
 }
 
 /// Implementation of tp_dealloc for pyclasses without gc
 pub(crate) unsafe extern "C" fn tp_dealloc<T: PyClass>(obj: *mut ffi::PyObject) {
-    crate::impl_::trampoline::dealloc(obj, PyCell::<T>::tp_dealloc)
+    crate::impl_::trampoline::dealloc(obj, PyClassObject::<T>::tp_dealloc)
 }
 
 /// Implementation of tp_dealloc for pyclasses with gc
@@ -1122,7 +1123,7 @@ pub(crate) unsafe extern "C" fn tp_dealloc_with_gc<T: PyClass>(obj: *mut ffi::Py
     {
         ffi::PyObject_GC_UnTrack(obj.cast());
     }
-    crate::impl_::trampoline::dealloc(obj, PyCell::<T>::tp_dealloc)
+    crate::impl_::trampoline::dealloc(obj, PyClassObject::<T>::tp_dealloc)
 }
 
 pub(crate) unsafe extern "C" fn get_sequence_item_from_mapping(

src/instance.rs

@@ -1,5 +1,6 @@
 use crate::err::{self, PyDowncastError, PyErr, PyResult};
 use crate::ffi_ptr_ext::FfiPtrExt;
+use crate::impl_::pycell::PyClassObject;
 use crate::pycell::{PyBorrowError, PyBorrowMutError, PyCell};
 use crate::pyclass::boolean_struct::{False, True};
 use crate::type_object::HasPyGilRef;
@@ -332,18 +333,14 @@ where
     where
         T: PyClass<Frozen = True> + Sync,
     {
-        let cell = self.get_cell();
-        // SAFETY: The class itself is frozen and `Sync` and we do not access anything but `cell.contents.value`.
-        unsafe { &*cell.get_ptr() }
+        // SAFETY: The class itself is frozen and `Sync`.
+        unsafe { &*self.get_class_object().get_ptr() }
     }
 
-    pub(crate) fn get_cell(&'py self) -> &'py PyCell<T> {
-        let cell = self.as_ptr().cast::<PyCell<T>>();
+    pub(crate) fn get_class_object(&self) -> &PyClassObject<T> {
+        let cell = self.as_ptr().cast::<PyClassObject<T>>();
         // SAFETY: Bound<T> is known to contain an object which is laid out in memory as a
-        // PyCell<T>.
-        //
-        // Strictly speaking for now `&'py PyCell<T>` is part of the "GIL Ref" API, so this
-        // could use some further refactoring later to avoid going through this reference.
+        // PyClassObject<T>.
         unsafe { &*cell }
     }
 }