PyO3 · davidhewitt · Aug 12, 2024 · Aug 12, 2024 · Aug 12, 2024
diff --git a/newsfragments/4434.changed.md b/newsfragments/4434.changed.md
@@ -0,0 +1,5 @@
+* The `PyO3::ffi` bindings for the C `PyObject` struct no longer derive from
+  `Copy` and `Clone`. If you use the ffi directly you will need to remove `Copy`
+  and `Clone` from any derived types. Any cases where a PyObject struct was
+  copied or cloned directly likely indicates a bug, it is not safe to allocate
+  PyObject structs outside of the Python runtime.
diff --git a/pyo3-ffi/src/bytearrayobject.rs b/pyo3-ffi/src/bytearrayobject.rs
@@ -5,7 +5,6 @@ use std::ptr::addr_of_mut;
 
 #[cfg(not(any(PyPy, GraalPy, Py_LIMITED_API)))]
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct PyByteArrayObject {
     pub ob_base: PyVarObject,
     pub ob_alloc: Py_ssize_t,

diff --git a/pyo3-ffi/src/complexobject.rs b/pyo3-ffi/src/complexobject.rs
@@ -26,7 +26,6 @@ extern "C" {
 }
 
 #[repr(C)]
-#[derive(Copy, Clone)]
 // non-limited
 pub struct PyComplexObject {
     pub ob_base: PyObject,

diff --git a/pyo3-ffi/src/cpython/bytesobject.rs b/pyo3-ffi/src/cpython/bytesobject.rs
@@ -6,7 +6,6 @@ use std::os::raw::c_int;
 
 #[cfg(not(any(PyPy, GraalPy, Py_LIMITED_API)))]
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct PyBytesObject {
     pub ob_base: PyVarObject,
     pub ob_shash: crate::Py_hash_t,

diff --git a/pyo3-ffi/src/cpython/code.rs b/pyo3-ffi/src/cpython/code.rs
@@ -82,7 +82,6 @@ opaque_struct!(PyCodeObject);
 
 #[cfg(all(not(any(PyPy, GraalPy)), Py_3_7, not(Py_3_8)))]
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct PyCodeObject {
     pub ob_base: PyObject,
     pub co_argcount: c_int,
@@ -111,7 +110,6 @@ opaque_struct!(_PyExecutorArray);
 
 #[cfg(all(not(any(PyPy, GraalPy)), Py_3_8, not(Py_3_11)))]
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct PyCodeObject {
     pub ob_base: PyObject,
     pub co_argcount: c_int,
@@ -145,7 +143,6 @@ pub struct PyCodeObject {
 
 #[cfg(all(not(any(PyPy, GraalPy)), Py_3_11))]
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct PyCodeObject {
     pub ob_base: PyVarObject,
     pub co_consts: *mut PyObject,
@@ -198,7 +195,6 @@ pub struct PyCodeObject {
 
 #[cfg(PyPy)]
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct PyCodeObject {
     pub ob_base: PyObject,
     pub co_name: *mut PyObject,

diff --git a/pyo3-ffi/src/cpython/frameobject.rs b/pyo3-ffi/src/cpython/frameobject.rs
@@ -21,7 +21,6 @@ pub struct PyTryBlock {
 }
 
 #[repr(C)]
-#[derive(Copy, Clone)]
 #[cfg(not(any(PyPy, GraalPy, Py_3_11)))]
 pub struct PyFrameObject {
     pub ob_base: PyVarObject,

diff --git a/pyo3-ffi/src/cpython/genobject.rs b/pyo3-ffi/src/cpython/genobject.rs
@@ -9,7 +9,6 @@ use std::ptr::addr_of_mut;
 
 #[cfg(not(any(PyPy, GraalPy)))]
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct PyGenObject {
     pub ob_base: PyObject,
     #[cfg(not(Py_3_11))]

diff --git a/pyo3-ffi/src/cpython/listobject.rs b/pyo3-ffi/src/cpython/listobject.rs
@@ -4,7 +4,6 @@ use crate::pyport::Py_ssize_t;
 
 #[cfg(not(any(PyPy, GraalPy)))]
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct PyListObject {
     pub ob_base: PyVarObject,
     pub ob_item: *mut *mut PyObject,

diff --git a/pyo3-ffi/src/cpython/object.rs b/pyo3-ffi/src/cpython/object.rs
@@ -205,7 +205,6 @@ pub type printfunc =
     unsafe extern "C" fn(arg1: *mut PyObject, arg2: *mut ::libc::FILE, arg3: c_int) -> c_int;
 
 #[repr(C)]
-#[derive(Debug, Copy, Clone)]
 pub struct PyTypeObject {
     #[cfg(all(PyPy, not(Py_3_9)))]
     pub ob_refcnt: Py_ssize_t,
@@ -301,7 +300,6 @@ pub struct _specialization_cache {
 }
 
 #[repr(C)]
-#[derive(Clone)]
 pub struct PyHeapTypeObject {
     pub ht_type: PyTypeObject,
     pub as_async: PyAsyncMethods,

diff --git a/pyo3-ffi/src/datetime.rs b/pyo3-ffi/src/datetime.rs
@@ -27,7 +27,6 @@ const _PyDateTime_TIME_DATASIZE: usize = 6;
 const _PyDateTime_DATETIME_DATASIZE: usize = 10;
 
 #[repr(C)]
-#[derive(Debug, Copy, Clone)]
 /// Structure representing a `datetime.timedelta`.
 pub struct PyDateTime_Delta {
     pub ob_base: PyObject,
@@ -46,7 +45,6 @@ pub struct PyDateTime_Delta {
 
 #[cfg(not(any(PyPy, GraalPy)))]
 #[repr(C)]
-#[derive(Debug, Copy, Clone)]
 /// Structure representing a `datetime.time` without a `tzinfo` member.
 pub struct _PyDateTime_BaseTime {
     pub ob_base: PyObject,
@@ -56,7 +54,6 @@ pub struct _PyDateTime_BaseTime {
 }
 
 #[repr(C)]
-#[derive(Debug, Copy, Clone)]
 /// Structure representing a `datetime.time`.
 pub struct PyDateTime_Time {
     pub ob_base: PyObject,
@@ -77,7 +74,6 @@ pub struct PyDateTime_Time {
 }
 
 #[repr(C)]
-#[derive(Debug, Copy, Clone)]
 /// Structure representing a `datetime.date`
 pub struct PyDateTime_Date {
     pub ob_base: PyObject,
@@ -91,7 +87,6 @@ pub struct PyDateTime_Date {
 
 #[cfg(not(any(PyPy, GraalPy)))]
 #[repr(C)]
-#[derive(Debug, Copy, Clone)]
 /// Structure representing a `datetime.datetime` without a `tzinfo` member.
 pub struct _PyDateTime_BaseDateTime {
     pub ob_base: PyObject,
@@ -101,7 +96,6 @@ pub struct _PyDateTime_BaseDateTime {
 }
 
 #[repr(C)]
-#[derive(Debug, Copy, Clone)]
 /// Structure representing a `datetime.datetime`.
 pub struct PyDateTime_DateTime {
     pub ob_base: PyObject,
@@ -130,26 +124,26 @@ pub struct PyDateTime_DateTime {
 /// Returns a signed integer greater than 0.
 pub unsafe fn PyDateTime_GET_YEAR(o: *mut PyObject) -> c_int {
     // This should work for Date or DateTime
-    let d = *(o as *mut PyDateTime_Date);
-    c_int::from(d.data[0]) << 8 | c_int::from(d.data[1])
+    let data = (*(o as *mut PyDateTime_Date)).data;
+    c_int::from(data[0]) << 8 | c_int::from(data[1])
 }
 
 #[inline]
 #[cfg(not(any(PyPy, GraalPy)))]
 /// Retrieve the month component of a `PyDateTime_Date` or `PyDateTime_DateTime`.
 /// Returns a signed integer in the range `[1, 12]`.
 pub unsafe fn PyDateTime_GET_MONTH(o: *mut PyObject) -> c_int {
-    let d = *(o as *mut PyDateTime_Date);
-    c_int::from(d.data[2])
+    let data = (*(o as *mut PyDateTime_Date)).data;
+    c_int::from(data[2])
 }
 
 #[inline]
 #[cfg(not(any(PyPy, GraalPy)))]
 /// Retrieve the day component of a `PyDateTime_Date` or `PyDateTime_DateTime`.
 /// Returns a signed integer in the interval `[1, 31]`.
 pub unsafe fn PyDateTime_GET_DAY(o: *mut PyObject) -> c_int {
-    let d = *(o as *mut PyDateTime_Date);
-    c_int::from(d.data[3])
+    let data = (*(o as *mut PyDateTime_Date)).data;
+    c_int::from(data[3])
 }
 
 // Accessor macros for times

diff --git a/pyo3-ffi/src/moduleobject.rs b/pyo3-ffi/src/moduleobject.rs
@@ -52,7 +52,6 @@ extern "C" {
 }
 
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct PyModuleDef_Base {
     pub ob_base: PyObject,
     pub m_init: Option<extern "C" fn() -> *mut PyObject>,
@@ -98,7 +97,6 @@ pub const Py_MOD_PER_INTERPRETER_GIL_SUPPORTED: *mut c_void = 2 as *mut c_void;
 // skipped non-limited _Py_mod_LAST_SLOT
 
 #[repr(C)]
-#[derive(Copy, Clone)]
 pub struct PyModuleDef {
     pub m_base: PyModuleDef_Base,
     pub m_name: *const c_char,

diff --git a/pyo3-ffi/src/object.rs b/pyo3-ffi/src/object.rs
@@ -61,7 +61,7 @@ impl std::fmt::Debug for PyObjectObRefcnt {
 pub type PyObjectObRefcnt = Py_ssize_t;
 
 #[repr(C)]
-#[derive(Copy, Clone, Debug)]
+#[derive(Debug)]
 pub struct PyObject {
     #[cfg(py_sys_config = "Py_TRACE_REFS")]
     pub _ob_next: *mut PyObject,
@@ -76,7 +76,7 @@ pub struct PyObject {
 // skipped _PyObject_CAST
 
 #[repr(C)]
-#[derive(Debug, Copy, Clone)]
+#[derive(Debug)]
 pub struct PyVarObject {
     pub ob_base: PyObject,
     #[cfg(not(GraalPy))]