(Failing) Set dictoffset and weaklistoffset by Py_tp_members

PyO3 · Sep 6, 2020 · bcceb24 · bcceb24
1 parent 8624306
commit bcceb24
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Showing 2 changed files with 55 additions and 17 deletions.
diff --git a/src/ffi/structmember.rs b/src/ffi/structmember.rs
@@ -3,13 +3,43 @@ use crate::ffi::pyport::Py_ssize_t;
 use std::os::raw::{c_char, c_int};
 
 #[repr(C)]
-#[derive(Copy, Clone)]
+#[derive(Clone)]
 pub struct PyMemberDef {
-    pub name: *mut c_char,
+    pub name: *const c_char,
     pub type_code: c_int,
     pub offset: Py_ssize_t,
     pub flags: c_int,
-    pub doc: *mut c_char,
+    pub doc: *const c_char,
+}
+
+impl PyMemberDef {
+    pub const fn init() -> Self {
+        Self {
+            name: std::ptr::null(),
+            type_code: 0,
+            offset: 0,
+            flags: 0,
+            doc: std::ptr::null(),
+        }
+    }
+    pub(crate) const fn dict_offset(offset: Py_ssize_t) -> Self {
+        Self {
+            name: "__dictoffset__\0".as_ptr() as _,
+            type_code: T_PYSSIZET,
+            offset: offset,
+            flags: READONLY,
+            doc: std::ptr::null(),
+        }
+    }
+    pub(crate) fn weakref_offset(offset: Py_ssize_t) -> Self {
+        Self {
+            name: "__weaklistoffset__\0".as_ptr() as _,
+            type_code: T_PYSSIZET,
+            offset: offset,
+            flags: READONLY,
+            doc: std::ptr::null(),
+        }
+    }
 }
 
 /* Types */

diff --git a/src/pyclass.rs b/src/pyclass.rs
@@ -3,6 +3,7 @@ use crate::class::methods::{PyClassAttributeDef, PyMethodDefType, PyMethods};
 use crate::class::proto_methods::PyProtoMethods;
 use crate::conversion::{AsPyPointer, FromPyPointer};
 use crate::derive_utils::PyBaseTypeUtils;
+use crate::ffi::structmember::PyMemberDef;
 use crate::pyclass_slots::{PyClassDict, PyClassWeakRef};
 use crate::type_object::{type_flags, PyLayout};
 use crate::types::PyAny;
@@ -168,6 +169,12 @@ where
         slots.push(ffi::Py_tp_getset, into_raw(props));
     }
 
+    // members
+    let members = py_class_members::<T>();
+    if !members.is_empty() {
+        slots.push(ffi::Py_tp_members, into_raw(members));
+    }
+
     // basic methods
     T::basic_methods().map(|basic| unsafe { basic.as_ref() }.update_slots(&mut slots));
     // number methods
@@ -205,32 +212,33 @@ where
 
 #[cfg(not(Py_LIMITED_API))]
 fn tp_init_additional<T: PyClass>(type_object: *mut ffi::PyTypeObject) {
-    // Just patch the type objects for the things there's no
-    // PyType_FromSpec API for... there's no reason this should work,
-    // except for that it does and we have tests.
     if let Some(buffer) = T::buffer_methods() {
         unsafe {
             (*(*type_object).tp_as_buffer).bf_getbuffer = buffer.as_ref().bf_getbuffer;
             (*(*type_object).tp_as_buffer).bf_releasebuffer = buffer.as_ref().bf_releasebuffer;
         }
     }
+}
+
+#[cfg(Py_LIMITED_API)]
+fn tp_init_additional<T: PyClass>(type_object: *mut ffi::PyTypeObject) {}
+
+fn py_class_members<T: PyClass>() -> Vec<PyMemberDef> {
+    let mut members = vec![];
     // __dict__ support
-    if let Some(dict_offset) = PyCell::<T>::dict_offset() {
-        unsafe {
-            (*type_object).tp_dictoffset = dict_offset as ffi::Py_ssize_t;
-        }
+    if let Some(offset) = PyCell::<T>::dict_offset() {
+        members.push(PyMemberDef::dict_offset(offset as _));
     }
     // weakref support
-    if let Some(weakref_offset) = PyCell::<T>::weakref_offset() {
-        unsafe {
-            (*type_object).tp_weaklistoffset = weakref_offset as ffi::Py_ssize_t;
-        }
+    if let Some(offset) = PyCell::<T>::weakref_offset() {
+        members.push(PyMemberDef::weakref_offset(offset as _));
+    }
+    if !members.is_empty() {
+        members.push(PyMemberDef::init());
     }
+    members
 }
 
-#[cfg(Py_LIMITED_API)]
-fn tp_init_additional<T: PyClass>(type_object: *mut ffi::PyTypeObject) {}
-
 fn py_class_flags<T: PyClass + PyTypeInfo>() -> c_uint {
     let mut flags = if T::gc_methods().is_some() || T::FLAGS & type_flags::GC != 0 {
         ffi::Py_TPFLAGS_DEFAULT | ffi::Py_TPFLAGS_HAVE_GC