Enable cloning of shared borrows into NumPy arrays.

Author: adamreichold

src/borrow.rs

@@ -275,6 +275,16 @@ where
     }
 }
 
+impl<'a, T, D> Clone for PyReadonlyArray<'a, T, D>
+where
+    T: Element,
+    D: Dimension,
+{
+    fn clone(&self) -> Self {
+        Self::try_new(self.0).unwrap()
+    }
+}
+
 impl<'a, T, D> Drop for PyReadonlyArray<'a, T, D> {
     fn drop(&mut self) {
         let address = base_address(self.0);

tests/borrow.rs

@@ -115,6 +115,19 @@ fn borrows_span_threads() {
     });
 }
 
+#[test]
+fn shared_borrows_can_be_cloned() {
+    Python::with_gil(|py| {
+        let array = PyArray::<f64, _>::zeros(py, (1, 2, 3), false);
+
+        let shared1 = array.readonly();
+        let shared2 = shared1.clone();
+
+        assert_eq!(shared2.shape(), [1, 2, 3]);
+        assert_eq!(shared1.shape(), [1, 2, 3]);
+    });
+}
+
 #[test]
 #[should_panic(expected = "AlreadyBorrowed")]
 fn overlapping_views_conflict() {