Manual forward port of 64962 - use PyObject_HashNotImplemented as a tp_hash level indicator that the default hash implementation has not been inherited

5 files changed, 38 insertions, 17 deletions

diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index eb57666..828803c 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -2031,7 +2031,7 @@ PyTypeObject PyDict_Type = {
 	0,					/* tp_as_number */
 	&dict_as_sequence,			/* tp_as_sequence */
 	&dict_as_mapping,			/* tp_as_mapping */
-	0,					/* tp_hash */
+	(hashfunc)PyObject_HashNotImplemented,	/* tp_hash */
 	0,					/* tp_call */
 	0,					/* tp_str */
 	PyObject_GenericGetAttr,		/* tp_getattro */
diff --git a/Objects/listobject.c b/Objects/listobject.c
index 255f087..af3ed2c 100644
--- a/Objects/listobject.c
+++ b/Objects/listobject.c
@@ -2568,7 +2568,7 @@ PyTypeObject PyList_Type = {
 	0,					/* tp_as_number */
 	&list_as_sequence,			/* tp_as_sequence */
 	&list_as_mapping,			/* tp_as_mapping */
-	0,					/* tp_hash */
+	(hashfunc)PyObject_HashNotImplemented,	/* tp_hash */
 	0,					/* tp_call */
 	0,					/* tp_str */
 	PyObject_GenericGetAttr,		/* tp_getattro */
diff --git a/Objects/object.c b/Objects/object.c
index 85bb850..ff16994 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -781,17 +781,22 @@ finally:
 #endif
 }
 
+long
+PyObject_HashNotImplemented(PyObject *v)
+{
+	PyErr_Format(PyExc_TypeError, "unhashable type: '%.200s'",
+		     Py_TYPE(v)->tp_name);
+	return -1;
+}
 
 long
 PyObject_Hash(PyObject *v)
 {
-	PyTypeObject *tp = v->ob_type;
+	PyTypeObject *tp = Py_TYPE(v);
 	if (tp->tp_hash != NULL)
 		return (*tp->tp_hash)(v);
 	/* Otherwise, the object can't be hashed */
-	PyErr_Format(PyExc_TypeError, "unhashable type: '%.200s'",
-		     v->ob_type->tp_name);
-	return -1;
+	return PyObject_HashNotImplemented(v);
 }
 
 PyObject *
diff --git a/Objects/setobject.c b/Objects/setobject.c
index 79598f2..771f47e 100644
--- a/Objects/setobject.c
+++ b/Objects/setobject.c
@@ -2092,7 +2092,7 @@ PyTypeObject PySet_Type = {
 	&set_as_number,			/* tp_as_number */
 	&set_as_sequence,		/* tp_as_sequence */
 	0,				/* tp_as_mapping */
-	0,				/* tp_hash */
+	(hashfunc)PyObject_HashNotImplemented,	/* tp_hash */
 	0,				/* tp_call */
 	0,				/* tp_str */
 	PyObject_GenericGetAttr,	/* tp_getattro */
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index c139fbc..9306552 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -3810,13 +3810,15 @@ PyType_Ready(PyTypeObject *type)
 
 	/* Hack for tp_hash and __hash__.
 	   If after all that, tp_hash is still NULL, and __hash__ is not in
-	   tp_dict, set tp_dict['__hash__'] equal to None.
+	   tp_dict, set tp_hash to PyObject_HashNotImplemented and
+	   tp_dict['__hash__'] equal to None.
 	   This signals that __hash__ is not inherited.
 	 */
 	if (type->tp_hash == NULL) {
 		if (PyDict_GetItemString(type->tp_dict, "__hash__") == NULL) {
 			if (PyDict_SetItemString(type->tp_dict, "__hash__", Py_None) < 0)
 				goto error;
+			type->tp_hash = PyObject_HashNotImplemented;
 		}
 	}
 
@@ -4943,9 +4945,7 @@ slot_tp_hash(PyObject *self)
 	}
 
 	if (func == NULL) {
-		PyErr_Format(PyExc_TypeError, "unhashable type: '%.200s'",
-			     Py_TYPE(self)->tp_name);
-		return -1;
+		return PyObject_HashNotImplemented(self);
         }
 
 	res = PyEval_CallObject(func, NULL);
@@ -5676,6 +5676,13 @@ update_one_slot(PyTypeObject *type, slotdef *p)
 			   sanity checks.  I'll buy the first person to
 			   point out a bug in this reasoning a beer. */
 		}
+		else if (descr == Py_None &&
+			 strcmp(p->name, "__hash__") == 0) {
+			/* We specifically allow __hash__ to be set to None
+			   to prevent inheritance of the default
+			   implementation from object.__hash__ */
+			specific = PyObject_HashNotImplemented;
+		}
 		else {
 			use_generic = 1;
 			generic = p->function;
@@ -5889,12 +5896,21 @@ add_operators(PyTypeObject *type)
 			continue;
 		if (PyDict_GetItem(dict, p->name_strobj))
 			continue;
-		descr = PyDescr_NewWrapper(type, p, *ptr);
-		if (descr == NULL)
-			return -1;
-		if (PyDict_SetItem(dict, p->name_strobj, descr) < 0)
-			return -1;
-		Py_DECREF(descr);
+		if (*ptr == PyObject_HashNotImplemented) {
+			/* Classes may prevent the inheritance of the tp_hash
+			   slot by storing PyObject_HashNotImplemented in it. Make it
+ 			   visible as a None value for the __hash__ attribute. */
+			if (PyDict_SetItem(dict, p->name_strobj, Py_None) < 0)
+				return -1;
+		}
+		else {
+			descr = PyDescr_NewWrapper(type, p, *ptr);
+			if (descr == NULL)
+				return -1;
+			if (PyDict_SetItem(dict, p->name_strobj, descr) < 0)
+				return -1;
+			Py_DECREF(descr);
+		}
 	}
 	if (type->tp_new != NULL) {
 		if (add_tp_new_wrapper(type) < 0)