gh-104614: Make Sure ob_type is Always Set Correctly by PyType_Ready() (gh-105122)

When I added the relevant condition to type_ready_set_bases() in gh-103912, I had missed that the function also sets tp_base and ob_type (if necessary).  That led to problems for third-party static types.

We fix that here, by making those extra operations distinct and by adjusting the condition to be more specific.

1 files changed, 45 insertions, 0 deletions

diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index d7c89f4..38c2d1a 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -2640,6 +2640,50 @@ type_get_tp_mro(PyObject *self, PyObject *type)
 }
 
 
+/* We only use 2 in test_capi/test_misc.py. */
+#define NUM_BASIC_STATIC_TYPES 2
+static PyTypeObject BasicStaticTypes[NUM_BASIC_STATIC_TYPES] = {
+#define INIT_BASIC_STATIC_TYPE \
+    { \
+        PyVarObject_HEAD_INIT(NULL, 0) \
+        .tp_name = "BasicStaticType", \
+        .tp_basicsize = sizeof(PyObject), \
+    }
+    INIT_BASIC_STATIC_TYPE,
+    INIT_BASIC_STATIC_TYPE,
+#undef INIT_BASIC_STATIC_TYPE
+};
+static int num_basic_static_types_used = 0;
+
+static PyObject *
+get_basic_static_type(PyObject *self, PyObject *args)
+{
+    PyObject *base = NULL;
+    if (!PyArg_ParseTuple(args, "|O", &base)) {
+        return NULL;
+    }
+    assert(base == NULL || PyType_Check(base));
+
+    if(num_basic_static_types_used >= NUM_BASIC_STATIC_TYPES) {
+        PyErr_SetString(PyExc_RuntimeError, "no more available basic static types");
+        return NULL;
+    }
+    PyTypeObject *cls = &BasicStaticTypes[num_basic_static_types_used++];
+
+    if (base != NULL) {
+        cls->tp_base = (PyTypeObject *)Py_NewRef(base);
+        cls->tp_bases = Py_BuildValue("(O)", base);
+        if (cls->tp_bases == NULL) {
+            return NULL;
+        }
+    }
+    if (PyType_Ready(cls) < 0) {
+        return NULL;
+    }
+    return (PyObject *)cls;
+}
+
+
 // Test PyThreadState C API
 static PyObject *
 test_tstate_capi(PyObject *self, PyObject *Py_UNUSED(args))
@@ -3395,6 +3439,7 @@ static PyMethodDef TestMethods[] = {
     {"type_assign_version", type_assign_version, METH_O, PyDoc_STR("PyUnstable_Type_AssignVersionTag")},
     {"type_get_tp_bases", type_get_tp_bases, METH_O},
     {"type_get_tp_mro", type_get_tp_mro, METH_O},
+    {"get_basic_static_type", get_basic_static_type, METH_VARARGS, NULL},
     {"test_tstate_capi", test_tstate_capi, METH_NOARGS, NULL},
     {"frame_getlocals", frame_getlocals, METH_O, NULL},
     {"frame_getglobals", frame_getglobals, METH_O, NULL},