Change mem::uninitialized to mem::MaybeUninit

Author: palaviv

vm/src/import.rs

@@ -106,7 +106,7 @@ fn remove_importlib_frames_inner(
     tb: Option<PyTracebackRef>,
     always_trim: bool,
 ) -> Option<PyTracebackRef> {
-    let traceback = tb.as_ref()?;;
+    let traceback = tb.as_ref()?;
     let file_name = traceback.frame.code.source_path.to_string();
     if (file_name == "_frozen_importlib" || file_name == "_frozen_importlib_external")
         && (always_trim || traceback.frame.code.obj_name == "_call_with_frames_removed")

vm/src/obj/objmemory.rs

@@ -1,5 +1,3 @@
-use std::borrow::Borrow;
-
 use super::objbyteinner::try_as_byte;
 use super::objtype::{issubclass, PyClassRef};
 use crate::pyobject::{PyClassImpl, PyContext, PyObjectRef, PyRef, PyResult, PyValue};
@@ -26,7 +24,7 @@ impl PyMemoryView {
         bytes_object: PyObjectRef,
         vm: &VirtualMachine,
     ) -> PyResult<PyMemoryViewRef> {
-        let object_type = bytes_object.typ.borrow();
+        let object_type = unsafe { &*bytes_object.typ.as_ptr() };
 
         if issubclass(object_type, &vm.ctx.types.memoryview_type)
             || issubclass(object_type, &vm.ctx.types.bytes_type)

vm/src/obj/objtype.rs

@@ -1,6 +1,7 @@
 use std::cell::RefCell;
 use std::collections::HashMap;
 use std::fmt;
+use std::mem::MaybeUninit;
 
 use super::objdict::PyDictRef;
 use super::objlist::PyList;
@@ -505,7 +506,7 @@ pub fn new(
             slots: RefCell::default(),
         },
         dict: None,
-        typ,
+        typ: MaybeUninit::new(typ),
     }
     .into_ref();
 

vm/src/pyobject.rs

@@ -3,6 +3,7 @@ use std::cell::Cell;
 use std::collections::HashMap;
 use std::fmt;
 use std::marker::PhantomData;
+use std::mem::MaybeUninit;
 use std::ops::Deref;
 use std::rc::Rc;
 
@@ -521,7 +522,7 @@ impl PyContext {
 
     pub fn new_instance(&self, class: PyClassRef, dict: Option<PyDictRef>) -> PyObjectRef {
         PyObject {
-            typ: class,
+            typ: MaybeUninit::new(class),
             dict,
             payload: objobject::PyInstance,
         }
@@ -565,7 +566,7 @@ pub struct PyObject<T>
 where
     T: ?Sized + PyObjectPayload,
 {
-    pub typ: PyClassRef,
+    pub typ: MaybeUninit<PyClassRef>,
     pub dict: Option<PyDictRef>, // __dict__ member
     pub payload: T,
 }
@@ -792,13 +793,13 @@ where
     T: ?Sized + PyObjectPayload,
 {
     fn class(&self) -> PyClassRef {
-        self.typ.clone()
+        unsafe { (*self.typ.as_ptr()).clone() }
     }
 }
 
 impl<T> TypeProtocol for PyRef<T> {
     fn class(&self) -> PyClassRef {
-        self.obj.typ.clone()
+        unsafe { (*self.obj.typ.as_ptr()).clone() }
     }
 }
 
@@ -1038,7 +1039,12 @@ where
 {
     #[allow(clippy::new_ret_no_self)]
     pub fn new(payload: T, typ: PyClassRef, dict: Option<PyDictRef>) -> PyObjectRef {
-        PyObject { typ, dict, payload }.into_ref()
+        PyObject {
+            typ: MaybeUninit::new(typ),
+            dict,
+            payload,
+        }
+        .into_ref()
     }
 
     // Move this object into a reference object, transferring ownership.

vm/src/types.rs

@@ -37,8 +37,7 @@ use crate::obj::objweakref;
 use crate::obj::objzip;
 use crate::pyobject::{PyAttributes, PyContext, PyObject, PyObjectRef};
 use std::cell::RefCell;
-use std::mem;
-use std::ptr;
+use std::mem::MaybeUninit;
 
 /// Holder of references to builtin types.
 #[derive(Debug)]
@@ -232,7 +231,7 @@ fn init_type_hierarchy() -> (PyClassRef, PyClassRef) {
     // (and yes, this will never get dropped. TODO?)
     let (type_type, object_type) = unsafe {
         let object_type = PyObject {
-            typ: mem::uninitialized(), // !
+            typ: MaybeUninit::uninit(), // !
             dict: None,
             payload: PyClass {
                 name: String::from("object"),
@@ -246,7 +245,7 @@ fn init_type_hierarchy() -> (PyClassRef, PyClassRef) {
         .into_ref();
 
         let type_type = PyObject {
-            typ: mem::uninitialized(), // !
+            typ: MaybeUninit::uninit(), // !
             dict: None,
             payload: PyClass {
                 name: String::from("type"),
@@ -265,8 +264,8 @@ fn init_type_hierarchy() -> (PyClassRef, PyClassRef) {
         let type_type: PyClassRef = type_type.downcast().unwrap();
         let object_type: PyClassRef = object_type.downcast().unwrap();
 
-        ptr::write(&mut (*object_type_ptr).typ, type_type.clone());
-        ptr::write(&mut (*type_type_ptr).typ, type_type.clone());
+        (*object_type_ptr).typ.as_mut_ptr().write(type_type.clone());
+        (*type_type_ptr).typ.as_mut_ptr().write(type_type.clone());
 
         (type_type, object_type)
     };