fixes

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "pyo3"
-version = "0.23.1"
+version = "0.24.0"
 description = "Bindings to Python interpreter"
 authors = ["PyO3 Project and Contributors <https://github.com/PyO3>"]
 readme = "README.md"
@@ -12,7 +12,7 @@ categories = ["api-bindings", "development-tools::ffi"]
 license = "MIT OR Apache-2.0"
 exclude = ["/.gitignore", ".cargo/config", "/codecov.yml", "/Makefile", "/pyproject.toml", "/noxfile.py", "/.github", "/tests/test_compile_error.rs", "/tests/ui"]
 edition = "2021"
-rust-version = "1.65"
+rust-version = "1.63"
 
 [dependencies]
 cfg-if = "1.0"

newsfragments/4678.added.md

@@ -1 +1 @@
-Add support for extending variable/unknown sized base classes (eg `type` to create metaclasses)
+Add support for opaque PyObjects allowing extending variable/unknown sized base classes (including `type` to create metaclasses)

pyo3-macros-backend/src/pyclass.rs

@@ -1198,7 +1198,7 @@ fn impl_complex_enum_variant_match_args(
         });
         parse_quote! {
             #[allow(non_upper_case_globals)]
-            const __match_args__: ( #(#args_tp,)* ) = (
+            const #ident: ( #(#args_tp,)* ) = (
                 #(stringify!(#field_names),)*
             );
         }

src/exceptions.rs

@@ -276,7 +276,8 @@ macro_rules! impl_windows_native_exception (
         pub struct $name($crate::PyAny);
 
         $crate::impl_exception_boilerplate!($name);
-        $crate::pyobject_native_type!($name, $layout, |_py| unsafe { $crate::ffi::$exc_name as *mut $crate::ffi::PyTypeObject });
+        $crate::pyobject_native_type!($name, $layout);
+        $crate::pyobject_native_type_object_methods!($name, #global_ptr=$crate::ffi::$exc_name);
     );
     ($name:ident, $exc_name:ident, $doc:expr) => (
         impl_windows_native_exception!($name, $exc_name, $doc, $crate::ffi::PyBaseExceptionObject);

src/internal_tricks.rs

@@ -47,3 +47,15 @@ pub(crate) const fn ptr_from_ref<T>(t: &T) -> *const T {
 pub(crate) fn ptr_from_mut<T>(t: &mut T) -> *mut T {
     t as *mut T
 }
+
+// TODO: use ptr::cast_mut on MSRV 1.65
+#[inline]
+pub(crate) fn cast_mut<T>(t: *const T) -> *mut T {
+    t as *mut T
+}
+
+// TODO: use ptr::cast_const on MSRV 1.65
+#[inline]
+pub(crate) fn cast_const<T>(t: *mut T) -> *const T {
+    t as *const T
+}

src/pycell/layout.rs

@@ -6,10 +6,13 @@ use std::marker::PhantomData;
 use std::mem::ManuallyDrop;
 use std::ptr::addr_of_mut;
 
+use memoffset::offset_of;
+
 use crate::impl_::pyclass::{
     PyClassBaseType, PyClassDict, PyClassImpl, PyClassThreadChecker, PyClassWeakRef, PyObjectOffset,
 };
 use crate::internal::get_slot::{TP_DEALLOC, TP_FREE};
+use crate::internal_tricks::{cast_const, cast_mut};
 use crate::pycell::borrow_checker::{GetBorrowChecker, PyClassBorrowChecker};
 use crate::type_object::PyNativeType;
 use crate::types::PyType;
@@ -175,6 +178,7 @@ impl<T: PyNativeType + PyTypeInfo> PyObjectRecursiveOperations
                 .get_slot(TP_DEALLOC)
                 .expect("PyType_Type should have tp_dealloc");
             // `PyType_Type::dealloc` calls `Py_GC_UNTRACK` so we have to re-track before deallocating
+            #[cfg(not(PyPy))]
             ffi::PyObject_GC_Track(obj.cast());
             return tp_dealloc(obj.cast());
         }
@@ -214,7 +218,7 @@ pub(crate) mod opaque_layout {
     use crate::{impl_::pyclass::PyClassImpl, PyTypeInfo};
 
     #[cfg(Py_3_12)]
-    pub fn get_contents_ptr<T: PyClassImpl + PyTypeInfo>(
+    pub(crate) fn get_contents_ptr<T: PyClassImpl + PyTypeInfo>(
         obj: *mut ffi::PyObject,
         strategy: TypeObjectStrategy<'_>,
     ) -> *mut PyClassObjectContents<T> {
@@ -356,7 +360,7 @@ impl PyObjectLayout {
             let obj: *mut static_layout::PyStaticClassLayout<T> = obj.cast();
             // indicates `ob_base` has type InvalidBaseLayout
             debug_assert_ne!(
-                std::mem::offset_of!(static_layout::PyStaticClassLayout<T>, contents),
+                offset_of!(static_layout::PyStaticClassLayout<T>, contents),
                 0,
                 "invalid ob_base found"
             );
@@ -372,10 +376,10 @@ impl PyObjectLayout {
         obj: &'a ffi::PyObject,
         strategy: TypeObjectStrategy<'_>,
     ) -> &'a PyClassObjectContents<T> {
-        unsafe {
-            &*PyObjectLayout::get_contents_ptr::<T>(ptr_from_ref(obj).cast_mut(), strategy)
-                .cast_const()
-        }
+        &*cast_const(PyObjectLayout::get_contents_ptr::<T>(
+            cast_mut(ptr_from_ref(obj)),
+            strategy,
+        ))
     }
 
     /// Obtain a pointer to the portion of `obj` containing the data for `T`
@@ -398,7 +402,7 @@ impl PyObjectLayout {
         obj: &'a ffi::PyObject,
         strategy: TypeObjectStrategy<'_>,
     ) -> &'a T {
-        unsafe { &*PyObjectLayout::get_data_ptr::<T>(ptr_from_ref(obj).cast_mut(), strategy) }
+        &*PyObjectLayout::get_data_ptr::<T>(cast_mut(ptr_from_ref(obj)), strategy)
     }
 
     /// Obtain a reference to the borrow checker for `obj`
@@ -436,9 +440,7 @@ impl PyObjectLayout {
         py: Python<'_>,
         obj: *mut ffi::PyObject,
     ) {
-        unsafe {
-            PyClassRecursiveOperations::<T>::deallocate(py, obj);
-        };
+        PyClassRecursiveOperations::<T>::deallocate(py, obj);
     }
 
     /// Clean up then free the memory associated with `obj`.
@@ -450,13 +452,11 @@ impl PyObjectLayout {
         py: Python<'_>,
         obj: *mut ffi::PyObject,
     ) {
-        unsafe {
-            #[cfg(not(PyPy))]
-            {
-                ffi::PyObject_GC_UnTrack(obj.cast());
-            }
-            PyClassRecursiveOperations::<T>::deallocate(py, obj);
-        };
+        #[cfg(not(PyPy))]
+        {
+            ffi::PyObject_GC_UnTrack(obj.cast());
+        }
+        PyClassRecursiveOperations::<T>::deallocate(py, obj);
     }
 
     /// Used to set `PyType_Spec::basicsize` when creating a `PyTypeObject` for `T`
@@ -613,6 +613,7 @@ mod static_tests {
     /// Test the functions calculate properties about the static layout without requiring an instance.
     /// The class in this test requires extra space for the `dict` and `weaklist` fields
     #[test]
+    #[cfg(any(Py_3_9, not(Py_LIMITED_API)))]
     fn test_layout_properties_no_inheritance_optional_fields() {
         #[pyclass(crate = "crate", dict, weakref, extends=PyAny)]
         struct MyClass(#[allow(unused)] u64);
@@ -1041,7 +1042,7 @@ mod static_tests {
             contents: u8,
         }
 
-        assert_eq!(std::mem::offset_of!(InvalidLayout, contents), 0);
+        assert_eq!(offset_of!(InvalidLayout, contents), 0);
     }
 }
 
@@ -1051,6 +1052,7 @@ mod static_tests {
 mod opaque_tests {
     use memoffset::offset_of;
     use static_assertions::const_assert;
+    use std::mem::size_of;
     use std::ops::Range;
 
     #[cfg(not(Py_LIMITED_API))]
@@ -1704,7 +1706,7 @@ mod opaque_fail_tests {
     )]
     fn test_panic_at_construction_inherit_opaque() {
         Python::with_gil(|py| {
-            Py::new(py, Metaclass::default()).unwrap();
+            Py::new(py, Metaclass).unwrap();
         });
     }
 
@@ -1726,6 +1728,7 @@ mod test_utils {
 
     /// The size in bytes of a [ffi::PyObject] of the type `T`
     #[cfg(not(Py_LIMITED_API))]
+    #[allow(unused)]
     pub fn get_pyobject_size<T: PyClass>(py: Python<'_>) -> usize {
         let typ = <T as PyTypeInfo>::type_object(py);
         let raw_typ = typ.as_ptr().cast::<ffi::PyTypeObject>();

src/types/set.rs

@@ -29,7 +29,6 @@ pyobject_native_type!(PySet, ffi::PySetObject, #checkfunction=ffi::PySet_Check);
 #[cfg(any(PyPy, GraalPy))]
 pyobject_native_type_core!(PySet, #checkfunction=ffi::PySet_Check);
 
-#[cfg(not(any(PyPy, GraalPy)))]
 pyobject_native_type_object_methods!(PySet, #global=ffi::PySet_Type);
 
 impl PySet {

tests/test_variable_sized_class_basics.rs

@@ -45,9 +45,7 @@ fn class_with_object_field() {
         let obj = Bound::new(py, ClassWithObjectField { value: None }).unwrap();
         py_run!(py, obj, "obj.value = 5");
         let obj_ref = obj.borrow();
-        let Some(value) = &obj_ref.value else {
-            panic!("obj_ref.value is None");
-        };
+        let value = obj_ref.value.as_ref().unwrap();
         assert_eq!(*value.downcast_bound::<PyInt>(py).unwrap(), 5);
     });
 }