Disallow instantiation and subtyping of _csv.Reader and `_csv.Write…

…r` types Set `Py_TPFLAGS_DISALLOW_INSTANTIATION` and unset `Py_TPFLAGS_BASETYPE` flags on `Reader` and `Writer` types to prevent their instantiation and subtyping
python · erlend-aasland · May 7, 2023 · May 7, 2023 · May 7, 2023 · May 7, 2023
commit ae69f9b8e4a8987ff814006f9b3731e0185d320b
diff --git a/Modules/_csv.c b/Modules/_csv.c
@@ -999,8 +999,8 @@ static PyType_Slot Reader_Type_slots[] = {
 PyType_Spec Reader_Type_spec = {
     .name = "_csv.reader",
     .basicsize = sizeof(ReaderObj),
-    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC |
-              Py_TPFLAGS_IMMUTABLETYPE),
+    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+              Py_TPFLAGS_IMMUTABLETYPE | Py_TPFLAGS_DISALLOW_INSTANTIATION),
     .slots = Reader_Type_slots
 };
 
@@ -1430,8 +1430,8 @@ static PyType_Slot Writer_Type_slots[] = {
 PyType_Spec Writer_Type_spec = {
     .name = "_csv.writer",
     .basicsize = sizeof(WriterObj),
-    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC |
-              Py_TPFLAGS_IMMUTABLETYPE),
+    .flags = (Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+              Py_TPFLAGS_IMMUTABLETYPE | Py_TPFLAGS_DISALLOW_INSTANTIATION),
     .slots = Writer_Type_slots,
 };