commit a14e53f1fe3147a2bf70dcb15bf3724b6a6a14d9
Author: Victor Stinner <vstinner@python.org>
Date:   Wed Jan 26 00:26:13 2022 +0100

    bpo-45476: Add PyDescr_SET_TYPE() and PyDescr_SET_NAME()
    
    Add PyDescr_SET_TYPE() and PyDescr_SET_NAME() macros to set the type
    and name of a descriptor (PyDescrObject structure):
    classmethod_descriptor, member_descriptor or getset_descriptor. The
    main usage of these macros is to create an instance of a descriptor
    subclass.

diff --git a/Doc/whatsnew/3.11.rst b/Doc/whatsnew/3.11.rst
index 4328ee6a50..f9e632b10a 100644
--- a/Doc/whatsnew/3.11.rst
+++ b/Doc/whatsnew/3.11.rst
@@ -677,6 +677,13 @@ New Features
   :c:macro:`PY_VERSION_HEX`.
   (Contributed by  Gabriele N. Tornetta in :issue:`43931`.)
 
+* Add ``PyDescr_SET_TYPE()`` and ``PyDescr_SET_NAME()`` macros to set the type
+  and name of a descriptor (``PyDescrObject`` structure):
+  ``classmethod_descriptor``, ``member_descriptor`` or ``getset_descriptor``.
+  The main usage of these macros is to create an instance of a descriptor
+  subclass.
+  (Contributed by Victor Stinner in :issue:`45476`.)
+
 
 Porting to Python 3.11
 ----------------------
diff --git a/Include/descrobject.h b/Include/descrobject.h
index 703bc8fd6d..960dfafdad 100644
--- a/Include/descrobject.h
+++ b/Include/descrobject.h
@@ -49,6 +49,14 @@ typedef struct {
 
 #define PyDescr_TYPE(x) (((PyDescrObject *)(x))->d_type)
 #define PyDescr_NAME(x) (((PyDescrObject *)(x))->d_name)
+#define PyDescr_QUALNAME(x) (((PyDescrObject *)(x))->d_qualname)
+
+#define PyDescr_SET_TYPE(x, type) \
+    do { (((PyDescrObject *)(x))->d_type = (type)) } while (0)
+#define PyDescr_SET_NAME(x, name) \
+    do { (((PyDescrObject *)(x))->d_name = (name)) } while (0)
+#define PyDescr_SET_QUALNAME(x, qualname) \
+    do { (((PyDescrObject *)(x))->d_qualname = (qualname)) } while (0)
 
 typedef struct {
     PyDescr_COMMON;
diff --git a/Misc/NEWS.d/next/C API/2022-01-26-00-31-20.bpo-45476.KiJM9A.rst b/Misc/NEWS.d/next/C API/2022-01-26-00-31-20.bpo-45476.KiJM9A.rst
new file mode 100644
index 0000000000..3c7c5148ae
--- /dev/null
+++ b/Misc/NEWS.d/next/C API/2022-01-26-00-31-20.bpo-45476.KiJM9A.rst	
@@ -0,0 +1,5 @@
+Add ``PyDescr_SET_TYPE()`` and ``PyDescr_SET_NAME()`` macros to set the type
+and name of a descriptor (``PyDescrObject`` structure):
+``classmethod_descriptor``, ``member_descriptor`` or ``getset_descriptor``. The
+main usage of these macros is to create an instance of a descriptor subclass.
+Patch by Victor Stinner.
diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 962136beae..ee176b37d5 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -599,10 +599,14 @@ calculate_qualname(PyDescrObject *descr)
 static PyObject *
 descr_get_qualname(PyDescrObject *descr, void *Py_UNUSED(ignored))
 {
-    if (descr->d_qualname == NULL)
-        descr->d_qualname = calculate_qualname(descr);
-    Py_XINCREF(descr->d_qualname);
-    return descr->d_qualname;
+    if (PyDescr_QUALNAME(descr) == NULL) {
+        PyObject *qualname = calculate_qualname(descr);
+        if (qualname == NULL) {
+            return NULL;
+        }
+        PyDescr_SET_QUALNAME(descr, qualname);
+    }
+    return Py_NewRef(PyDescr_QUALNAME(descr));
 }
 
 static PyObject *
@@ -876,24 +880,23 @@ PyTypeObject PyWrapperDescr_Type = {
     0,                                          /* tp_descr_set */
 };
 
-static PyDescrObject *
-descr_new(PyTypeObject *descrtype, PyTypeObject *type, const char *name)
+PyDescrObject *
+PyDescr_New(PyTypeObject *descrtype, PyTypeObject *type, const char *name)
 {
-    PyDescrObject *descr;
+    PyObject *name_obj = PyUnicode_InternFromString(name);
+    if (name_obj == NULL) {
+        return NULL;
+    }
 
-    descr = (PyDescrObject *)PyType_GenericAlloc(descrtype, 0);
-    if (descr != NULL) {
-        Py_XINCREF(type);
-        descr->d_type = type;
-        descr->d_name = PyUnicode_InternFromString(name);
-        if (descr->d_name == NULL) {
-            Py_DECREF(descr);
-            descr = NULL;
-        }
-        else {
-            descr->d_qualname = NULL;
-        }
+    PyDescrObject *descr = (PyDescrObject *)PyType_GenericAlloc(descrtype, 0);
+    if (descr == NULL)
+        Py_DECREF(name);
+        return NULL;
     }
+
+    PyDescr_SET_TYPE(descr, Py_XNewRef(type));
+    PyDescr_SET_NAME(descr, name_obj);
+    PyDescr_SET_QUALNAME(descr, NULL);
     return descr;
 }