Make SliceBox hide its internals and add a test case for SliceBox-induced type confusion.

Author: adamreichold

src/array.rs

@@ -448,8 +448,8 @@ impl<T: Element, D: Dimension> PyArray<T, D> {
         ID: IntoDimension<Dim = D>,
     {
         let dims = dims.into_dimension();
+        let data_ptr = data_ptr.unwrap_or(boxed_slice.as_ptr());
         let container = SliceBox::new(boxed_slice);
-        let data_ptr = data_ptr.unwrap_or(container.data.as_ptr());
         let cell = pyo3::PyClassInitializer::from(container)
             .create_cell(py)
             .expect("Object creation failed.");

src/slice_box.rs

@@ -1,10 +1,11 @@
 use pyo3::class::impl_::{PyClassImpl, ThreadCheckerStub};
 use pyo3::pyclass::PyClass;
 use pyo3::pyclass_slots::PyClassDummySlot;
-use pyo3::{ffi, type_object, types::PyAny, PyCell};
+use pyo3::type_object::{LazyStaticType, PyTypeInfo};
+use pyo3::{ffi, types::PyAny, PyCell};
 
 pub(crate) struct SliceBox<T> {
-    pub(crate) data: Box<[T]>,
+    data: Box<[T]>,
 }
 
 impl<T> SliceBox<T> {
@@ -33,7 +34,7 @@ where
     type ThreadChecker = ThreadCheckerStub<Self>;
 }
 
-unsafe impl<T> type_object::PyTypeInfo for SliceBox<T>
+unsafe impl<T> PyTypeInfo for SliceBox<T>
 where
     T: Send,
 {
@@ -43,7 +44,6 @@ where
 
     #[inline]
     fn type_object_raw(py: pyo3::Python) -> *mut ffi::PyTypeObject {
-        use pyo3::type_object::LazyStaticType;
         static TYPE_OBJECT: LazyStaticType = LazyStaticType::new();
         TYPE_OBJECT.get_or_init::<Self>(py)
     }

tests/to_py.rs

@@ -232,3 +232,23 @@ fn to_pyarray_object_array() {
         }
     })
 }
+
+#[test]
+fn slice_box_type_confusion() {
+    use ndarray::Array2;
+    use pyo3::{
+        types::{PyDict, PyString},
+        ToPyObject,
+    };
+
+    pyo3::Python::with_gil(|py| {
+        let mut nd_arr = Array2::from_shape_fn((2, 3), |(_, _)| py.None());
+        nd_arr[(0, 2)] = PyDict::new(py).to_object(py);
+        nd_arr[(1, 0)] = PyString::new(py, "Hello:)").to_object(py);
+
+        let _py_arr = nd_arr.into_pyarray(py);
+
+        let vec = vec![1, 2, 3];
+        let _arr = vec.into_pyarray(py);
+    });
+}