From b88415edf288cff6ab89b19bb7f7ca55ec1e6ade Mon Sep 17 00:00:00 2001
From: Eric Wieser <wieser.eric@gmail.com>
Date: Tue, 31 Mar 2020 17:58:15 +0100
Subject: BUG: Do not ignore empty tuple of strides in ndarray.__new__

Previously this was treated as though an empty set of strides were passed.

Now this is treated as a request for `.strides == ()`.
---
 numpy/core/src/multiarray/arrayobject.c | 7 ++++---
 numpy/core/tests/test_multiarray.py     | 6 ++++++
 2 files changed, 10 insertions(+), 3 deletions(-)

(limited to 'numpy')

diff --git a/numpy/core/src/multiarray/arrayobject.c b/numpy/core/src/multiarray/arrayobject.c
index 16896aa12..dedaf38eb 100644
--- a/numpy/core/src/multiarray/arrayobject.c
+++ b/numpy/core/src/multiarray/arrayobject.c
@@ -41,6 +41,7 @@ maintainer email:  oliphant.travis@ieee.org
 #include "arraytypes.h"
 #include "scalartypes.h"
 #include "arrayobject.h"
+#include "conversion_utils.h"
 #include "ctors.h"
 #include "methods.h"
 #include "descriptor.h"
@@ -1624,7 +1625,7 @@ array_new(PyTypeObject *subtype, PyObject *args, PyObject *kwds)
     PyArray_Descr *descr = NULL;
     int itemsize;
     PyArray_Dims dims = {NULL, 0};
-    PyArray_Dims strides = {NULL, 0};
+    PyArray_Dims strides = {NULL, -1};
     PyArray_Chunk buffer;
     npy_longlong offset = 0;
     NPY_ORDER order = NPY_CORDER;
@@ -1645,7 +1646,7 @@ array_new(PyTypeObject *subtype, PyObject *args, PyObject *kwds)
                                      PyArray_BufferConverter,
                                      &buffer,
                                      &offset,
-                                     &PyArray_IntpConverter,
+                                     &PyArray_OptionalIntpConverter,
                                      &strides,
                                      &PyArray_OrderConverter,
                                      &order)) {
@@ -1660,7 +1661,7 @@ array_new(PyTypeObject *subtype, PyObject *args, PyObject *kwds)
 
     itemsize = descr->elsize;
 
-    if (strides.ptr != NULL) {
+    if (strides.len != -1) {
         npy_intp nb, off;
         if (strides.len != dims.len) {
             PyErr_SetString(PyExc_ValueError,
diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
index 829679dab..470df6986 100644
--- a/numpy/core/tests/test_multiarray.py
+++ b/numpy/core/tests/test_multiarray.py
@@ -686,6 +686,12 @@ class TestZeroRank:
         y[()] = 6
         assert_equal(x[()], 6)
 
+        # strides and shape must be the same length
+        with pytest.raises(ValueError):
+            np.ndarray((2,), strides=())
+        with pytest.raises(ValueError):
+            np.ndarray((), strides=(2,))
+
     def test_output(self):
         x = np.array(2)
         assert_raises(ValueError, np.add, x, [1], x)
-- 
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