BUG: Fixed undefined behavior when __array_wrap__ returns None

Now `None` is treated like any other return value, rather than a command
to segfault.

2 files changed, 14 insertions, 3 deletions

diff --git a/numpy/core/src/umath/ufunc_object.c b/numpy/core/src/umath/ufunc_object.c
index 62024d2e3..69fb255fa 100644
--- a/numpy/core/src/umath/ufunc_object.c
+++ b/numpy/core/src/umath/ufunc_object.c
@@ -4395,6 +4395,7 @@ ufunc_generic_call(PyUFuncObject *ufunc, PyObject *args, PyObject *kwds)
                 continue;
             }
             res = PyObject_CallFunction(wrap, "O(OOi)", mps[j], ufunc, args, i);
+            /* Handle __array_wrap__ that does not accept a context argument */
             if (res == NULL && PyErr_ExceptionMatches(PyExc_TypeError)) {
                 PyErr_Clear();
                 res = PyObject_CallFunctionObjArgs(wrap, mps[j], NULL);
@@ -4403,9 +4404,6 @@ ufunc_generic_call(PyUFuncObject *ufunc, PyObject *args, PyObject *kwds)
             if (res == NULL) {
                 goto fail;
             }
-            else if (res == Py_None) {
-                Py_DECREF(res);
-            }
             else {
                 Py_DECREF(mps[j]);
                 retobj[i] = res;
diff --git a/numpy/core/tests/test_umath.py b/numpy/core/tests/test_umath.py
index 4c0243559..6fea832c9 100644
--- a/numpy/core/tests/test_umath.py
+++ b/numpy/core/tests/test_umath.py
@@ -1379,6 +1379,19 @@ class TestSpecialMethods(TestCase):
         a = A()
         self.assertRaises(RuntimeError, ncu.maximum, a, a)
 
+    def test_none_wrap(self):
+        # Tests that issue #8507 is resolved. Previously, this would segfault
+
+        class A(object):
+            def __array__(self):
+                return np.zeros(1)
+
+            def __array_wrap__(self, arr, context=None):
+                return None
+
+        a = A()
+        assert_equal(ncu.maximum(a, a), None)
+
     def test_default_prepare(self):
 
         class with_wrap(object):