gh-111178: fix UBSan failures in `Objects/typevarobject.c` (GH-129800)

Fix UBSan failures for `typealiasobject`, `paramspecobject`, `typevarobject`, `typevartupleobject`, `paramspecattrobject`

Use _PyCFunction_CAST macros

Use macro for `constevaluatorobject` casts

diff --git a/Objects/typevarobject.c b/Objects/typevarobject.c
index 4ed40aa71a595e76e592c5aa4f77009c089c883b..d8158293acaabd5d2caf552680f7b5dd46e70057 100644 (file)
--- a/Objects/typevarobject.c
+++ b/Objects/typevarobject.c
@@ -57,6 +57,11 @@ typedef struct {
     PyObject *module;
 } typealiasobject;
 
+#define typevarobject_CAST(op)      ((typevarobject *)(op))
+#define typevartupleobject_CAST(op) ((typevartupleobject *)(op))
+#define paramspecobject_CAST(op)    ((paramspecobject *)(op))
+#define typealiasobject_CAST(op)    ((typealiasobject *)(op))
+
 #include "clinic/typevarobject.c.h"
 
 /* NoDefault is a marker object to indicate that a parameter has no default. */
@@ -121,11 +126,13 @@ typedef struct {
     PyObject *value;
 } constevaluatorobject;
 
+#define constevaluatorobject_CAST(op)   ((constevaluatorobject *)(op))
+
 static void
 constevaluator_dealloc(PyObject *self)
 {
     PyTypeObject *tp = Py_TYPE(self);
-    constevaluatorobject *ce = (constevaluatorobject *)self;
+    constevaluatorobject *ce = constevaluatorobject_CAST(self);
 
     _PyObject_GC_UNTRACK(self);
 
@@ -138,7 +145,7 @@ constevaluator_dealloc(PyObject *self)
 static int
 constevaluator_traverse(PyObject *self, visitproc visit, void *arg)
 {
-    constevaluatorobject *ce = (constevaluatorobject *)self;
+    constevaluatorobject *ce = constevaluatorobject_CAST(self);
     Py_VISIT(ce->value);
     return 0;
 }
@@ -146,20 +153,22 @@ constevaluator_traverse(PyObject *self, visitproc visit, void *arg)
 static int
 constevaluator_clear(PyObject *self)
 {
-    Py_CLEAR(((constevaluatorobject *)self)->value);
+    constevaluatorobject *ce = constevaluatorobject_CAST(self);
+    Py_CLEAR(ce->value);
     return 0;
 }
 
 static PyObject *
 constevaluator_repr(PyObject *self)
 {
-    PyObject *value = ((constevaluatorobject *)self)->value;
-    return PyUnicode_FromFormat("<constevaluator %R>", value);
+    constevaluatorobject *ce = constevaluatorobject_CAST(self);
+    return PyUnicode_FromFormat("<constevaluator %R>", ce->value);
 }
 
 static PyObject *
 constevaluator_call(PyObject *self, PyObject *args, PyObject *kwargs)
 {
+    constevaluatorobject *ce = constevaluatorobject_CAST(self);
     if (!_PyArg_NoKeywords("constevaluator.__call__", kwargs)) {
         return NULL;
     }
@@ -167,7 +176,7 @@ constevaluator_call(PyObject *self, PyObject *args, PyObject *kwargs)
     if (!PyArg_ParseTuple(args, "i:constevaluator.__call__", &format)) {
         return NULL;
     }
-    PyObject *value = ((constevaluatorobject *)self)->value;
+    PyObject *value = ce->value;
     if (format == _Py_ANNOTATE_FORMAT_STRING) {
         PyUnicodeWriter *writer = PyUnicodeWriter_Create(5);  // cannot be <5
         if (writer == NULL) {
@@ -453,7 +462,7 @@ static void
 typevar_dealloc(PyObject *self)
 {
     PyTypeObject *tp = Py_TYPE(self);
-    typevarobject *tv = (typevarobject *)self;
+    typevarobject *tv = typevarobject_CAST(self);
 
     _PyObject_GC_UNTRACK(self);
 
@@ -475,7 +484,7 @@ static int
 typevar_traverse(PyObject *self, visitproc visit, void *arg)
 {
     Py_VISIT(Py_TYPE(self));
-    typevarobject *tv = (typevarobject *)self;
+    typevarobject *tv = typevarobject_CAST(self);
     Py_VISIT(tv->bound);
     Py_VISIT(tv->evaluate_bound);
     Py_VISIT(tv->constraints);
@@ -487,22 +496,23 @@ typevar_traverse(PyObject *self, visitproc visit, void *arg)
 }
 
 static int
-typevar_clear(typevarobject *self)
+typevar_clear(PyObject *op)
 {
+    typevarobject *self = typevarobject_CAST(op);
     Py_CLEAR(self->bound);
     Py_CLEAR(self->evaluate_bound);
     Py_CLEAR(self->constraints);
     Py_CLEAR(self->evaluate_constraints);
     Py_CLEAR(self->default_value);
     Py_CLEAR(self->evaluate_default);
-    PyObject_ClearManagedDict((PyObject *)self);
+    PyObject_ClearManagedDict(op);
     return 0;
 }
 
 static PyObject *
 typevar_repr(PyObject *self)
 {
-    typevarobject *tv = (typevarobject *)self;
+    typevarobject *tv = typevarobject_CAST(self);
 
     if (tv->infer_variance) {
         return Py_NewRef(tv->name);
@@ -521,8 +531,9 @@ static PyMemberDef typevar_members[] = {
 };
 
 static PyObject *
-typevar_bound(typevarobject *self, void *Py_UNUSED(ignored))
+typevar_bound(PyObject *op, void *Py_UNUSED(closure))
 {
+    typevarobject *self = typevarobject_CAST(op);
     if (self->bound != NULL) {
         return Py_NewRef(self->bound);
     }
@@ -535,8 +546,9 @@ typevar_bound(typevarobject *self, void *Py_UNUSED(ignored))
 }
 
 static PyObject *
-typevar_default(typevarobject *self, void *unused)
+typevar_default(PyObject *op, void *Py_UNUSED(closure))
 {
+    typevarobject *self = typevarobject_CAST(op);
     if (self->default_value != NULL) {
         return Py_NewRef(self->default_value);
     }
@@ -549,8 +561,9 @@ typevar_default(typevarobject *self, void *unused)
 }
 
 static PyObject *
-typevar_constraints(typevarobject *self, void *Py_UNUSED(ignored))
+typevar_constraints(PyObject *op, void *Py_UNUSED(closure))
 {
+    typevarobject *self = typevarobject_CAST(op);
     if (self->constraints != NULL) {
         return Py_NewRef(self->constraints);
     }
@@ -563,8 +576,9 @@ typevar_constraints(typevarobject *self, void *Py_UNUSED(ignored))
 }
 
 static PyObject *
-typevar_evaluate_bound(typevarobject *self, void *Py_UNUSED(ignored))
+typevar_evaluate_bound(PyObject *op, void *Py_UNUSED(closure))
 {
+    typevarobject *self = typevarobject_CAST(op);
     if (self->evaluate_bound != NULL) {
         return Py_NewRef(self->evaluate_bound);
     }
@@ -575,8 +589,9 @@ typevar_evaluate_bound(typevarobject *self, void *Py_UNUSED(ignored))
 }
 
 static PyObject *
-typevar_evaluate_constraints(typevarobject *self, void *Py_UNUSED(ignored))
+typevar_evaluate_constraints(PyObject *op, void *Py_UNUSED(closure))
 {
+    typevarobject *self = typevarobject_CAST(op);
     if (self->evaluate_constraints != NULL) {
         return Py_NewRef(self->evaluate_constraints);
     }
@@ -587,8 +602,9 @@ typevar_evaluate_constraints(typevarobject *self, void *Py_UNUSED(ignored))
 }
 
 static PyObject *
-typevar_evaluate_default(typevarobject *self, void *Py_UNUSED(ignored))
+typevar_evaluate_default(PyObject *op, void *Py_UNUSED(closure))
 {
+    typevarobject *self = typevarobject_CAST(op);
     if (self->evaluate_default != NULL) {
         return Py_NewRef(self->evaluate_default);
     }
@@ -599,12 +615,12 @@ typevar_evaluate_default(typevarobject *self, void *Py_UNUSED(ignored))
 }
 
 static PyGetSetDef typevar_getset[] = {
-    {"__bound__", (getter)typevar_bound, NULL, NULL, NULL},
-    {"__constraints__", (getter)typevar_constraints, NULL, NULL, NULL},
-    {"__default__", (getter)typevar_default, NULL, NULL, NULL},
-    {"evaluate_bound", (getter)typevar_evaluate_bound, NULL, NULL, NULL},
-    {"evaluate_constraints", (getter)typevar_evaluate_constraints, NULL, NULL, NULL},
-    {"evaluate_default", (getter)typevar_evaluate_default, NULL, NULL, NULL},
+    {"__bound__", typevar_bound, NULL, NULL, NULL},
+    {"__constraints__", typevar_constraints, NULL, NULL, NULL},
+    {"__default__", typevar_default, NULL, NULL, NULL},
+    {"evaluate_bound", typevar_evaluate_bound, NULL, NULL, NULL},
+    {"evaluate_constraints", typevar_evaluate_constraints, NULL, NULL, NULL},
+    {"evaluate_default", typevar_evaluate_default, NULL, NULL, NULL},
     {0}
 };
 
@@ -772,7 +788,7 @@ typevar_typing_prepare_subst_impl(typevarobject *self, PyObject *alias,
     }
     else if (i == args_len) {
         // If the TypeVar has a default, use it.
-        PyObject *dflt = typevar_default(self, NULL);
+        PyObject *dflt = typevar_default((PyObject *)self, NULL);
         if (dflt == NULL) {
             Py_DECREF(params);
             return NULL;
@@ -918,11 +934,13 @@ typedef struct {
     PyObject *__origin__;
 } paramspecattrobject;
 
+#define paramspecattrobject_CAST(op)    ((paramspecattrobject *)(op))
+
 static void
 paramspecattr_dealloc(PyObject *self)
 {
     PyTypeObject *tp = Py_TYPE(self);
-    paramspecattrobject *psa = (paramspecattrobject *)self;
+    paramspecattrobject *psa = paramspecattrobject_CAST(self);
 
     _PyObject_GC_UNTRACK(self);
 
@@ -935,14 +953,15 @@ paramspecattr_dealloc(PyObject *self)
 static int
 paramspecattr_traverse(PyObject *self, visitproc visit, void *arg)
 {
-    paramspecattrobject *psa = (paramspecattrobject *)self;
+    paramspecattrobject *psa = paramspecattrobject_CAST(self);
     Py_VISIT(psa->__origin__);
     return 0;
 }
 
 static int
-paramspecattr_clear(paramspecattrobject *self)
+paramspecattr_clear(PyObject *op)
 {
+    paramspecattrobject *self = paramspecattrobject_CAST(op);
     Py_CLEAR(self->__origin__);
     return 0;
 }
@@ -956,11 +975,9 @@ paramspecattr_richcompare(PyObject *a, PyObject *b, int op)
     if (op != Py_EQ && op != Py_NE) {
         Py_RETURN_NOTIMPLEMENTED;
     }
-    return PyObject_RichCompare(
-        ((paramspecattrobject *)a)->__origin__,
-        ((paramspecattrobject *)b)->__origin__,
-        op
-    );
+    paramspecattrobject *lhs = paramspecattrobject_CAST(a); // may be unsafe
+    paramspecattrobject *rhs = (paramspecattrobject *)b;    // safe fast cast
+    return PyObject_RichCompare(lhs->__origin__, rhs->__origin__, op);
 }
 
 static PyMemberDef paramspecattr_members[] = {
@@ -983,8 +1000,7 @@ paramspecattr_new(PyTypeObject *tp, PyObject *origin)
 static PyObject *
 paramspecargs_repr(PyObject *self)
 {
-    paramspecattrobject *psa = (paramspecattrobject *)self;
-
+    paramspecattrobject *psa = paramspecattrobject_CAST(self);
     PyTypeObject *tp = _PyInterpreterState_GET()->cached_objects.paramspec_type;
     if (Py_IS_TYPE(psa->__origin__, tp)) {
         return PyUnicode_FromFormat("%U.args",
@@ -1046,7 +1062,7 @@ static PyType_Slot paramspecargs_slots[] = {
     {Py_tp_alloc, PyType_GenericAlloc},
     {Py_tp_free, PyObject_GC_Del},
     {Py_tp_traverse, paramspecattr_traverse},
-    {Py_tp_clear, (inquiry)paramspecattr_clear},
+    {Py_tp_clear, paramspecattr_clear},
     {Py_tp_repr, paramspecargs_repr},
     {Py_tp_members, paramspecattr_members},
     {Py_tp_richcompare, paramspecattr_richcompare},
@@ -1064,7 +1080,7 @@ PyType_Spec paramspecargs_spec = {
 static PyObject *
 paramspeckwargs_repr(PyObject *self)
 {
-    paramspecattrobject *psk = (paramspecattrobject *)self;
+    paramspecattrobject *psk = paramspecattrobject_CAST(self);
 
     PyTypeObject *tp = _PyInterpreterState_GET()->cached_objects.paramspec_type;
     if (Py_IS_TYPE(psk->__origin__, tp)) {
@@ -1126,7 +1142,7 @@ static PyType_Slot paramspeckwargs_slots[] = {
     {Py_tp_alloc, PyType_GenericAlloc},
     {Py_tp_free, PyObject_GC_Del},
     {Py_tp_traverse, paramspecattr_traverse},
-    {Py_tp_clear, (inquiry)paramspecattr_clear},
+    {Py_tp_clear, paramspecattr_clear},
     {Py_tp_repr, paramspeckwargs_repr},
     {Py_tp_members, paramspecattr_members},
     {Py_tp_richcompare, paramspecattr_richcompare},
@@ -1145,7 +1161,7 @@ static void
 paramspec_dealloc(PyObject *self)
 {
     PyTypeObject *tp = Py_TYPE(self);
-    paramspecobject *ps = (paramspecobject *)self;
+    paramspecobject *ps = paramspecobject_CAST(self);
 
     _PyObject_GC_UNTRACK(self);
 
@@ -1164,7 +1180,7 @@ static int
 paramspec_traverse(PyObject *self, visitproc visit, void *arg)
 {
     Py_VISIT(Py_TYPE(self));
-    paramspecobject *ps = (paramspecobject *)self;
+    paramspecobject *ps = paramspecobject_CAST(self);
     Py_VISIT(ps->bound);
     Py_VISIT(ps->default_value);
     Py_VISIT(ps->evaluate_default);
@@ -1173,19 +1189,20 @@ paramspec_traverse(PyObject *self, visitproc visit, void *arg)
 }
 
 static int
-paramspec_clear(paramspecobject *self)
+paramspec_clear(PyObject *op)
 {
+    paramspecobject *self = paramspecobject_CAST(op);
     Py_CLEAR(self->bound);
     Py_CLEAR(self->default_value);
     Py_CLEAR(self->evaluate_default);
-    PyObject_ClearManagedDict((PyObject *)self);
+    PyObject_ClearManagedDict(op);
     return 0;
 }
 
 static PyObject *
 paramspec_repr(PyObject *self)
 {
-    paramspecobject *ps = (paramspecobject *)self;
+    paramspecobject *ps = paramspecobject_CAST(self);
 
     if (ps->infer_variance) {
         return Py_NewRef(ps->name);
@@ -1205,22 +1222,23 @@ static PyMemberDef paramspec_members[] = {
 };
 
 static PyObject *
-paramspec_args(PyObject *self, void *unused)
+paramspec_args(PyObject *self, void *Py_UNUSED(closure))
 {
     PyTypeObject *tp = _PyInterpreterState_GET()->cached_objects.paramspecargs_type;
     return (PyObject *)paramspecattr_new(tp, self);
 }
 
 static PyObject *
-paramspec_kwargs(PyObject *self, void *unused)
+paramspec_kwargs(PyObject *self, void *Py_UNUSED(closure))
 {
     PyTypeObject *tp = _PyInterpreterState_GET()->cached_objects.paramspeckwargs_type;
     return (PyObject *)paramspecattr_new(tp, self);
 }
 
 static PyObject *
-paramspec_default(paramspecobject *self, void *unused)
+paramspec_default(PyObject *op, void *Py_UNUSED(closure))
 {
+    paramspecobject *self = paramspecobject_CAST(op);
     if (self->default_value != NULL) {
         return Py_NewRef(self->default_value);
     }
@@ -1233,8 +1251,9 @@ paramspec_default(paramspecobject *self, void *unused)
 }
 
 static PyObject *
-paramspec_evaluate_default(paramspecobject *self, void *unused)
+paramspec_evaluate_default(PyObject *op, void *Py_UNUSED(closure))
 {
+    paramspecobject *self = paramspecobject_CAST(op);
     if (self->evaluate_default != NULL) {
         return Py_NewRef(self->evaluate_default);
     }
@@ -1245,10 +1264,10 @@ paramspec_evaluate_default(paramspecobject *self, void *unused)
 }
 
 static PyGetSetDef paramspec_getset[] = {
-    {"args", (getter)paramspec_args, NULL, PyDoc_STR("Represents positional arguments."), NULL},
-    {"kwargs", (getter)paramspec_kwargs, NULL, PyDoc_STR("Represents keyword arguments."), NULL},
-    {"__default__", (getter)paramspec_default, NULL, "The default value for this ParamSpec.", NULL},
-    {"evaluate_default", (getter)paramspec_evaluate_default, NULL, NULL, NULL},
+    {"args", paramspec_args, NULL, PyDoc_STR("Represents positional arguments."), NULL},
+    {"kwargs", paramspec_kwargs, NULL, PyDoc_STR("Represents keyword arguments."), NULL},
+    {"__default__", paramspec_default, NULL, "The default value for this ParamSpec.", NULL},
+    {"evaluate_default", paramspec_evaluate_default, NULL, NULL, NULL},
     {0},
 };
 
@@ -1492,7 +1511,7 @@ typevartuple_dealloc(PyObject *self)
 {
     PyTypeObject *tp = Py_TYPE(self);
     _PyObject_GC_UNTRACK(self);
-    typevartupleobject *tvt = (typevartupleobject *)self;
+    typevartupleobject *tvt = typevartupleobject_CAST(self);
 
     Py_DECREF(tvt->name);
     Py_XDECREF(tvt->default_value);
@@ -1525,8 +1544,7 @@ typevartuple_iter(PyObject *self)
 static PyObject *
 typevartuple_repr(PyObject *self)
 {
-    typevartupleobject *tvt = (typevartupleobject *)self;
-
+    typevartupleobject *tvt = typevartupleobject_CAST(self);
     return Py_NewRef(tvt->name);
 }
 
@@ -1658,8 +1676,9 @@ static int
 typevartuple_traverse(PyObject *self, visitproc visit, void *arg)
 {
     Py_VISIT(Py_TYPE(self));
-    Py_VISIT(((typevartupleobject *)self)->default_value);
-    Py_VISIT(((typevartupleobject *)self)->evaluate_default);
+    typevartupleobject *tvt = typevartupleobject_CAST(self);
+    Py_VISIT(tvt->default_value);
+    Py_VISIT(tvt->evaluate_default);
     PyObject_VisitManagedDict(self, visit, arg);
     return 0;
 }
@@ -1667,15 +1686,17 @@ typevartuple_traverse(PyObject *self, visitproc visit, void *arg)
 static int
 typevartuple_clear(PyObject *self)
 {
-    Py_CLEAR(((typevartupleobject *)self)->default_value);
-    Py_CLEAR(((typevartupleobject *)self)->evaluate_default);
+    typevartupleobject *tvt = typevartupleobject_CAST(self);
+    Py_CLEAR(tvt->default_value);
+    Py_CLEAR(tvt->evaluate_default);
     PyObject_ClearManagedDict(self);
     return 0;
 }
 
 static PyObject *
-typevartuple_default(typevartupleobject *self, void *unused)
+typevartuple_default(PyObject *op, void *Py_UNUSED(closure))
 {
+    typevartupleobject *self = typevartupleobject_CAST(op);
     if (self->default_value != NULL) {
         return Py_NewRef(self->default_value);
     }
@@ -1688,8 +1709,9 @@ typevartuple_default(typevartupleobject *self, void *unused)
 }
 
 static PyObject *
-typevartuple_evaluate_default(typevartupleobject *self, void *unused)
+typevartuple_evaluate_default(PyObject *op, void *Py_UNUSED(closure))
 {
+    typevartupleobject *self = typevartupleobject_CAST(op);
     if (self->evaluate_default != NULL) {
         return Py_NewRef(self->evaluate_default);
     }
@@ -1700,8 +1722,8 @@ typevartuple_evaluate_default(typevartupleobject *self, void *unused)
 }
 
 static PyGetSetDef typevartuple_getset[] = {
-    {"__default__", (getter)typevartuple_default, NULL, "The default value for this TypeVarTuple.", NULL},
-    {"evaluate_default", (getter)typevartuple_evaluate_default, NULL, NULL, NULL},
+    {"__default__", typevartuple_default, NULL, "The default value for this TypeVarTuple.", NULL},
+    {"evaluate_default", typevartuple_evaluate_default, NULL, NULL, NULL},
     {0},
 };
 
@@ -1803,13 +1825,13 @@ static PyObject *
 get_type_param_default(PyThreadState *ts, PyObject *typeparam) {
     // Does not modify refcount of existing objects.
     if (Py_IS_TYPE(typeparam, ts->interp->cached_objects.typevar_type)) {
-        return typevar_default((typevarobject *)typeparam, NULL);
+        return typevar_default(typeparam, NULL);
     }
     else if (Py_IS_TYPE(typeparam, ts->interp->cached_objects.paramspec_type)) {
-        return paramspec_default((paramspecobject *)typeparam, NULL);
+        return paramspec_default(typeparam, NULL);
     }
     else if (Py_IS_TYPE(typeparam, ts->interp->cached_objects.typevartuple_type)) {
-        return typevartuple_default((typevartupleobject *)typeparam, NULL);
+        return typevartuple_default(typeparam, NULL);
     }
     else {
         PyErr_Format(PyExc_TypeError, "Expected a type param, got %R", typeparam);
@@ -1822,7 +1844,7 @@ typealias_dealloc(PyObject *self)
 {
     PyTypeObject *tp = Py_TYPE(self);
     _PyObject_GC_UNTRACK(self);
-    typealiasobject *ta = (typealiasobject *)self;
+    typealiasobject *ta = typealiasobject_CAST(self);
     Py_DECREF(ta->name);
     Py_XDECREF(ta->type_params);
     Py_XDECREF(ta->compute_value);
@@ -1859,16 +1881,16 @@ static PyMemberDef typealias_members[] = {
 };
 
 static PyObject *
-typealias_value(PyObject *self, void *unused)
+typealias_value(PyObject *self, void *Py_UNUSED(closure))
 {
-    typealiasobject *ta = (typealiasobject *)self;
+    typealiasobject *ta = typealiasobject_CAST(self);
     return typealias_get_value(ta);
 }
 
 static PyObject *
-typealias_evaluate_value(PyObject *self, void *unused)
+typealias_evaluate_value(PyObject *self, void *Py_UNUSED(closure))
 {
-    typealiasobject *ta = (typealiasobject *)self;
+    typealiasobject *ta = typealiasobject_CAST(self);
     if (ta->compute_value != NULL) {
         return Py_NewRef(ta->compute_value);
     }
@@ -1877,9 +1899,9 @@ typealias_evaluate_value(PyObject *self, void *unused)
 }
 
 static PyObject *
-typealias_parameters(PyObject *self, void *unused)
+typealias_parameters(PyObject *self, void *Py_UNUSED(closure))
 {
-    typealiasobject *ta = (typealiasobject *)self;
+    typealiasobject *ta = typealiasobject_CAST(self);
     if (ta->type_params == NULL) {
         return PyTuple_New(0);
     }
@@ -1887,9 +1909,9 @@ typealias_parameters(PyObject *self, void *unused)
 }
 
 static PyObject *
-typealias_type_params(PyObject *self, void *unused)
+typealias_type_params(PyObject *self, void *Py_UNUSED(closure))
 {
-    typealiasobject *ta = (typealiasobject *)self;
+    typealiasobject *ta = typealiasobject_CAST(self);
     if (ta->type_params == NULL) {
         return PyTuple_New(0);
     }
@@ -1897,9 +1919,9 @@ typealias_type_params(PyObject *self, void *unused)
 }
 
 static PyObject *
-typealias_module(PyObject *self, void *unused)
+typealias_module(PyObject *self, void *Py_UNUSED(closure))
 {
-    typealiasobject *ta = (typealiasobject *)self;
+    typealiasobject *ta = typealiasobject_CAST(self);
     if (ta->module != NULL) {
         return Py_NewRef(ta->module);
     }
@@ -1916,11 +1938,11 @@ typealias_module(PyObject *self, void *unused)
 }
 
 static PyGetSetDef typealias_getset[] = {
-    {"__parameters__", typealias_parameters, (setter)NULL, NULL, NULL},
-    {"__type_params__", typealias_type_params, (setter)NULL, NULL, NULL},
-    {"__value__", typealias_value, (setter)NULL, NULL, NULL},
-    {"evaluate_value", typealias_evaluate_value, (setter)NULL, NULL, NULL},
-    {"__module__", typealias_module, (setter)NULL, NULL, NULL},
+    {"__parameters__", typealias_parameters, NULL, NULL, NULL},
+    {"__type_params__", typealias_type_params, NULL, NULL, NULL},
+    {"__value__", typealias_value, NULL, NULL, NULL},
+    {"evaluate_value", typealias_evaluate_value, NULL, NULL, NULL},
+    {"__module__", typealias_module, NULL, NULL, NULL},
     {0}
 };
 
@@ -2001,8 +2023,9 @@ typealias_alloc(PyObject *name, PyObject *type_params, PyObject *compute_value,
 }
 
 static int
-typealias_traverse(typealiasobject *self, visitproc visit, void *arg)
+typealias_traverse(PyObject *op, visitproc visit, void *arg)
 {
+    typealiasobject *self = typealiasobject_CAST(op);
     Py_VISIT(self->type_params);
     Py_VISIT(self->compute_value);
     Py_VISIT(self->value);
@@ -2011,8 +2034,9 @@ typealias_traverse(typealiasobject *self, visitproc visit, void *arg)
 }
 
 static int
-typealias_clear(typealiasobject *self)
+typealias_clear(PyObject *op)
 {
+    typealiasobject *self = typealiasobject_CAST(op);
     Py_CLEAR(self->type_params);
     Py_CLEAR(self->compute_value);
     Py_CLEAR(self->value);
@@ -2033,14 +2057,15 @@ typealias_reduce_impl(typealiasobject *self)
 }
 
 static PyObject *
-typealias_subscript(PyObject *self, PyObject *args)
+typealias_subscript(PyObject *op, PyObject *args)
 {
-    if (((typealiasobject *)self)->type_params == NULL) {
+    typealiasobject *self = typealiasobject_CAST(op);
+    if (self->type_params == NULL) {
         PyErr_SetString(PyExc_TypeError,
                         "Only generic type aliases are subscriptable");
         return NULL;
     }
-    return Py_GenericAlias(self, args);
+    return Py_GenericAlias(op, args);
 }
 
 static PyMethodDef typealias_methods[] = {
@@ -2133,8 +2158,8 @@ PyTypeObject _PyTypeAlias_Type = {
     .tp_dealloc = typealias_dealloc,
     .tp_new = typealias_new,
     .tp_free = PyObject_GC_Del,
-    .tp_traverse = (traverseproc)typealias_traverse,
-    .tp_clear = (inquiry)typealias_clear,
+    .tp_traverse = typealias_traverse,
+    .tp_clear = typealias_clear,
     .tp_repr = typealias_repr,
     .tp_as_number = &typealias_as_number,
     .tp_as_mapping = &typealias_as_mapping,
@@ -2252,10 +2277,10 @@ _Py_subscript_generic(PyThreadState* unused, PyObject *params)
 }
 
 static PyMethodDef generic_methods[] = {
-    {"__class_getitem__", (PyCFunction)(void (*)(void))generic_class_getitem,
+    {"__class_getitem__", _PyCFunction_CAST(generic_class_getitem),
      METH_VARARGS | METH_KEYWORDS | METH_CLASS,
      generic_class_getitem_doc},
-    {"__init_subclass__", (PyCFunction)(void (*)(void))generic_init_subclass,
+    {"__init_subclass__", _PyCFunction_CAST(generic_init_subclass),
      METH_VARARGS | METH_KEYWORDS | METH_CLASS,
      PyDoc_STR("Function to initialize subclasses.")},
     {NULL} /* Sentinel */