ENH: normalize 'sig' to 'signature' in ufunc override

Closes #5674

2 files changed, 24 insertions, 1 deletions

diff --git a/numpy/core/src/private/ufunc_override.h b/numpy/core/src/private/ufunc_override.h
index c47c46a66..c3f9f601e 100644
--- a/numpy/core/src/private/ufunc_override.h
+++ b/numpy/core/src/private/ufunc_override.h
@@ -13,7 +13,14 @@ normalize___call___args(PyUFuncObject *ufunc, PyObject *args,
 {
     /* ufunc.__call__(*args, **kwds) */
     int nargs = PyTuple_GET_SIZE(args);
-    PyObject *obj;
+    PyObject *obj = PyDict_GetItemString(*normal_kwds, "sig");
+
+    /* ufuncs accept 'sig' or 'signature' normalize to 'signature' */
+    if (obj != NULL) {
+        Py_INCREF(obj);
+        PyDict_SetItemString(*normal_kwds, "signature", obj);
+        PyDict_DelItemString(*normal_kwds, "sig");
+    }
 
     *normal_args = PyTuple_GetSlice(args, 0, nin);
 
diff --git a/numpy/core/tests/test_multiarray.py b/numpy/core/tests/test_multiarray.py
index 0c13cff6a..93d0cb6b9 100644
--- a/numpy/core/tests/test_multiarray.py
+++ b/numpy/core/tests/test_multiarray.py
@@ -2313,6 +2313,22 @@ class TestBinop(object):
         assert_equal(obj2.sum(), 42)
         assert_(isinstance(obj2, SomeClass2))
 
+    def test_ufunc_override_normalize_signature(self):
+        # gh-5674
+        class SomeClass(object):
+            def __numpy_ufunc__(self, ufunc, method, i, inputs, **kw):
+                return kw
+
+        a = SomeClass()
+        kw = np.add(a, [1])
+        assert_('sig' not in kw and 'signature' not in kw)
+        kw = np.add(a, [1], sig='ii->i')
+        assert_('sig' not in kw and 'signature' in kw)
+        assert_equal(kw['signature'], 'ii->i')
+        kw = np.add(a, [1], signature='ii->i')
+        assert_('sig' not in kw and 'signature' in kw)
+        assert_equal(kw['signature'], 'ii->i')
+
 
 class TestCAPI(TestCase):
     def test_IsPythonScalar(self):