commit eb65e2443ac21739baf6d373abc7b4638b9d6927
author Jeroen Demeyer <J.Demeyer@UGent.be> Tue May 28 14:42:53 2019 +0200
committer Petr Viktorin <encukou@gmail.com> Tue May 28 14:42:53 2019 +0200
tree 2197fa4322a60cbe077dfb8c03e0287cd3baabd9
parent 0811f2d81a12a3415dc2cb2744b41520c48d4db5

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

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

Objects/descrobject.c

diff --git a/Objects/descrobject.c b/Objects/descrobject.c
index 0db8057..6c99f9b 100644
--- a/Objects/descrobject.c
+++ b/Objects/descrobject.c
@@ -556,7 +556,8 @@
     PyObject_GenericGetAttr,                    /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+    Py_TPFLAGS_METHOD_DESCRIPTOR,               /* tp_flags */
     0,                                          /* tp_doc */
     descr_traverse,                             /* tp_traverse */
     0,                                          /* tp_clear */
@@ -705,7 +706,8 @@
     PyObject_GenericGetAttr,                    /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC, /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+    Py_TPFLAGS_METHOD_DESCRIPTOR,               /* tp_flags */
     0,                                          /* tp_doc */
     descr_traverse,                             /* tp_traverse */
     0,                                          /* tp_clear */

Objects/funcobject.c

diff --git a/Objects/funcobject.c b/Objects/funcobject.c
index 09b94c2..fb7abfa 100644
--- a/Objects/funcobject.c
+++ b/Objects/funcobject.c
@@ -663,7 +663,8 @@
     0,                                          /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
+    Py_TPFLAGS_METHOD_DESCRIPTOR,               /* tp_flags */
     func_new__doc__,                            /* tp_doc */
     (traverseproc)func_traverse,                /* tp_traverse */
     (inquiry)func_clear,                        /* tp_clear */

Objects/object.c

diff --git a/Objects/object.c b/Objects/object.c
index 270716f..87dba98 100644
--- a/Objects/object.c
+++ b/Objects/object.c
@@ -1155,8 +1155,7 @@
     descr = _PyType_Lookup(tp, name);
     if (descr != NULL) {
         Py_INCREF(descr);
-        if (PyFunction_Check(descr) ||
-                (Py_TYPE(descr) == &PyMethodDescr_Type)) {
+        if (PyType_HasFeature(Py_TYPE(descr), Py_TPFLAGS_METHOD_DESCRIPTOR)) {
             meth_found = 1;
         } else {
             f = descr->ob_type->tp_descr_get;

Objects/typeobject.c

diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index fc809d3..06e045b 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -4950,7 +4950,7 @@
 inherit_special(PyTypeObject *type, PyTypeObject *base)
 {
 
-    /* Copying basicsize is connected to the GC flags */
+    /* Copying tp_traverse and tp_clear is connected to the GC flags */
     if (!(type->tp_flags & Py_TPFLAGS_HAVE_GC) &&
         (base->tp_flags & Py_TPFLAGS_HAVE_GC) &&
         (!type->tp_traverse && !type->tp_clear)) {
@@ -5165,6 +5165,15 @@
     }
     {
         COPYSLOT(tp_descr_get);
+        /* Inherit Py_TPFLAGS_METHOD_DESCRIPTOR if tp_descr_get was inherited,
+         * but only for extension types */
+        if (base->tp_descr_get &&
+            type->tp_descr_get == base->tp_descr_get &&
+            !(type->tp_flags & Py_TPFLAGS_HEAPTYPE) &&
+            (base->tp_flags & Py_TPFLAGS_METHOD_DESCRIPTOR))
+        {
+            type->tp_flags |= Py_TPFLAGS_METHOD_DESCRIPTOR;
+        }
         COPYSLOT(tp_descr_set);
         COPYSLOT(tp_dictoffset);
         COPYSLOT(tp_init);