fix and add test

src/capi/object.cpp

@@ -569,6 +569,7 @@ extern "C" PyObject** _PyObject_GetDictPtr(PyObject* obj) noexcept {
     Py_ssize_t dictoffset;
     PyTypeObject* tp = Py_TYPE(obj);
 
+    if (!tp->instancesHaveHCAttrs()) {
         dictoffset = tp->tp_dictoffset;
         if (dictoffset == 0)
             return NULL;
@@ -586,6 +587,10 @@ extern "C" PyObject** _PyObject_GetDictPtr(PyObject* obj) noexcept {
             assert(dictoffset % SIZEOF_VOID_P == 0);
         }
         return (PyObject**)((char*)obj + dictoffset);
+    } else {
+        fatalOrError(PyExc_NotImplementedError, "unimplemented for hcattrs");
+        return nullptr;
+    }
 }
 
 /* These methods are used to control infinite recursion in repr, str, print,

test/tests/datetime_test.py

@@ -2,6 +2,16 @@
 # Doesn't test much of the functionality, but even importing the module is tough:
 
 import datetime
+
+def typeErrorTest(val):
+    try:
+        x = datetime.timedelta(43)
+        x // val
+    except TypeError as e:
+        return True
+    return False
+
+
 print repr(datetime.time())
 print datetime.datetime.__base__
 print repr(datetime.datetime(1, 2, 3))
@@ -11,3 +21,8 @@ print str(datetime.timedelta(0))
 datetime.datetime.now().now()
 
 print datetime.datetime(1924, 2, 3).strftime("%B %d, %Y - %X")
+
+a = 3
+b = 3.4
+assert not typeErrorTest(a)
+assert typeErrorTest(b)