MAINT: Ensure that block returns a new array

In the case that a user calls
np.block(array),
the old block function would return a view into the array.

This ensures that a new array is returned

1 files changed, 8 insertions, 1 deletions

diff --git a/numpy/core/shape_base.py b/numpy/core/shape_base.py
index 30919ed7e..d10bce608 100644
--- a/numpy/core/shape_base.py
+++ b/numpy/core/shape_base.py
@@ -620,4 +620,11 @@ def block(arrays):
                 _block_format_index(bottom_index)
             )
         )
-    return _block(arrays, list_ndim, max(arr_ndim, list_ndim))
+    result = _block(arrays, list_ndim, max(arr_ndim, list_ndim))
+    if list_ndim == 0:
+        # Catch an edge case where _block returns a view because
+        # `arrays` is a single numpy array and not a list of numpy arrays.
+        # This might copy scalars or lists twice, but this isn't a likely
+        # usecase for those interested in performance
+        result = result.copy()
+    return result