bpo-36922: implement PEP-590 Py_TPFLAGS_METHOD_DESCRIPTOR (GH-13338)

Co-authored-by: Mark Shannon <mark@hotpy.org>

2 files changed, 59 insertions, 1 deletions

diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c
index dcc9129..13f2db9 100644
--- a/Modules/_functoolsmodule.c
+++ b/Modules/_functoolsmodule.c
@@ -1333,7 +1333,8 @@ static PyTypeObject lru_cache_type = {
     0,                                  /* tp_getattro */
     0,                                  /* tp_setattro */
     0,                                  /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE|Py_TPFLAGS_HAVE_GC,
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE |
+    Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_METHOD_DESCRIPTOR,
                                         /* tp_flags */
     lru_cache_doc,                      /* tp_doc */
     (traverseproc)lru_cache_tp_traverse,/* tp_traverse */
diff --git a/Modules/_testcapimodule.c b/Modules/_testcapimodule.c
index 51e5d80..8ba9270 100644
--- a/Modules/_testcapimodule.c
+++ b/Modules/_testcapimodule.c
@@ -5787,6 +5787,46 @@ static PyTypeObject Generic_Type = {
 };
 
 
+/* Test PEP 590 */
+
+static PyObject *
+func_descr_get(PyObject *func, PyObject *obj, PyObject *type)
+{
+    if (obj == Py_None || obj == NULL) {
+        Py_INCREF(func);
+        return func;
+    }
+    return PyMethod_New(func, obj);
+}
+
+static PyObject *
+nop_descr_get(PyObject *func, PyObject *obj, PyObject *type)
+{
+    Py_INCREF(func);
+    return func;
+}
+
+static PyTypeObject MethodDescriptorBase_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "MethodDescriptorBase",
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_METHOD_DESCRIPTOR,
+    .tp_descr_get = func_descr_get,
+};
+
+static PyTypeObject MethodDescriptorDerived_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "MethodDescriptorDerived",
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+};
+
+static PyTypeObject MethodDescriptorNopGet_Type = {
+    PyVarObject_HEAD_INIT(NULL, 0)
+    "MethodDescriptorNopGet",
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+    .tp_descr_get = nop_descr_get,
+};
+
+
 static struct PyModuleDef _testcapimodule = {
     PyModuleDef_HEAD_INIT,
     "_testcapi",
@@ -5834,6 +5874,23 @@ PyInit__testcapi(void)
     Py_INCREF(&MyList_Type);
     PyModule_AddObject(m, "MyList", (PyObject *)&MyList_Type);
 
+    if (PyType_Ready(&MethodDescriptorBase_Type) < 0)
+        return NULL;
+    Py_INCREF(&MethodDescriptorBase_Type);
+    PyModule_AddObject(m, "MethodDescriptorBase", (PyObject *)&MethodDescriptorBase_Type);
+
+    MethodDescriptorDerived_Type.tp_base = &MethodDescriptorBase_Type;
+    if (PyType_Ready(&MethodDescriptorDerived_Type) < 0)
+        return NULL;
+    Py_INCREF(&MethodDescriptorDerived_Type);
+    PyModule_AddObject(m, "MethodDescriptorDerived", (PyObject *)&MethodDescriptorDerived_Type);
+
+    MethodDescriptorNopGet_Type.tp_base = &MethodDescriptorBase_Type;
+    if (PyType_Ready(&MethodDescriptorNopGet_Type) < 0)
+        return NULL;
+    Py_INCREF(&MethodDescriptorNopGet_Type);
+    PyModule_AddObject(m, "MethodDescriptorNopGet", (PyObject *)&MethodDescriptorNopGet_Type);
+
     if (PyType_Ready(&GenericAlias_Type) < 0)
         return NULL;
     Py_INCREF(&GenericAlias_Type);