add release note, error out if offset is used

numpy · Nov 9, 2021 · f6076ee · f6076ee
1 parent c38b7f3
commit f6076ee
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diff --git a/doc/release/upcoming_changes/19083.new_feature.rst b/doc/release/upcoming_changes/19083.new_feature.rst
@@ -0,0 +1,6 @@
+Add NEP 47-compatible dlpack support
+------------------------------------
+
+Add a ``ndarray.__dlpack__()`` method which returns a ``dlpack`` C structure
+wrapped in a ``PyCapsule``. Also add a ``np._from_dlpack(obj)`` function, where
+``obj`` supports ``__dlpack__()``, and returns an ``ndarray``.
diff --git a/numpy/core/src/multiarray/dlpack.c b/numpy/core/src/multiarray/dlpack.c
@@ -206,6 +206,12 @@ array_dlpack(PyArrayObject *self,
     if (data == NULL) {
         return NULL;
     }
+    if ((char *)PyArray_DATA(self) - data != 0) {
+        PyErr_SetString(PyExc_TypeError,
+                        "Offsets not clearly supported by this "
+                        "version of DLPack.");
+        return NULL;
+    }
 
     DLManagedTensor *managed = PyMem_Malloc(sizeof(DLManagedTensor));
     if (managed == NULL) {
@@ -238,7 +244,7 @@ array_dlpack(PyArrayObject *self,
     if (PyArray_SIZE(self) != 1 && !PyArray_IS_C_CONTIGUOUS(self)) {
         managed->dl_tensor.strides = managed_strides;
     }
-    managed->dl_tensor.byte_offset = (char *)PyArray_DATA(self) - data;
+    managed->dl_tensor.byte_offset = 0;
     managed->manager_ctx = self;
     managed->deleter = array_dlpack_deleter;