Funnel all assignments to PyArrayObject->base through a single point

This patch removes all direct assignments of non-NULL values to the
'base' field on PyArrayObjects. A new utility function was created to
set up UPDATEIFCOPY arrays, and all assignments to 'base' were
adjusted to use either PyArray_SetBaseObject or the new
PyArray_SetUpdateIfCopyBase.

One advantage of this is that it produces more consistent error
handling. This error handling revealed a bug in the nditer code,
which this patch does *not* yet fix.

The bug is that npyiter_new_temp_array sometimes (when dealing with
reversed axes) creates an array and then returns a view onto it. But,
npyiter_allocate_arrays assumes that the array returned by
npyiter_new_temp_array can have UPDATEIFCOPY set, which requires
reassigning its 'base' field. Previously, this meant that the
temporary array leaked. Now, it produces a ValueError.

This code path doesn't seem to actually be hit very often; only one of
the nditer tests fails because of the change. See
   numpy/core/tests/test_nditer.py:test_iter_array_cast_buggy

1 files changed, 1 insertions, 3 deletions

diff --git a/numpy/numarray/_capi.c b/numpy/numarray/_capi.c
index b6e5c1a3c..6acf7324a 100644
--- a/numpy/numarray/_capi.c
+++ b/numpy/numarray/_capi.c
@@ -1101,12 +1101,10 @@ NA_OutputArray(PyObject *a, NumarrayType t, int requires)
                                         PyArray_DIMS((PyArrayObject *)a),
                                         dtype, 0);
     Py_INCREF(a);
-    if (PyArray_SetBaseObject(ret, a) < 0) {
+    if (PyArray_SetUpdateIfCopyBase(ret, a) < 0) {
         Py_DECREF(ret);
         return NULL;
     }
-    PyArray_ENABLEFLAGS(ret, NPY_ARRAY_UPDATEIFCOPY);
-    PyArray_CLEARFLAGS((PyArrayObject *)a, NPY_ARRAY_WRITEABLE);
     return ret;
 }