bpo-42747: Remove Py_TPFLAGS_HAVE_AM_SEND and make Py_TPFLAGS_HAVE_VERSION_TAG no-op (GH-27260)

* Remove code that checks Py_TPFLAGS_HAVE_VERSION_TAG
    
    The field is always present in the type struct, as explained
    in the added comment.

* Remove Py_TPFLAGS_HAVE_AM_SEND
    
    The flag is not needed, and since it was added in 3.10 it can be removed now.

3 files changed, 6 insertions, 30 deletions

diff --git a/Objects/abstract.c b/Objects/abstract.c
index f14a923..842c367 100644
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -2804,9 +2804,7 @@ PyIter_Send(PyObject *iter, PyObject *arg, PyObject **result)
     _Py_IDENTIFIER(send);
     assert(arg != NULL);
     assert(result != NULL);
-    if (PyType_HasFeature(Py_TYPE(iter), Py_TPFLAGS_HAVE_AM_SEND)) {
-        assert (Py_TYPE(iter)->tp_as_async != NULL);
-        assert (Py_TYPE(iter)->tp_as_async->am_send != NULL);
+    if (Py_TYPE(iter)->tp_as_async && Py_TYPE(iter)->tp_as_async->am_send) {
         PySendResult res = Py_TYPE(iter)->tp_as_async->am_send(iter, arg, result);
         assert(_Py_CheckSlotResult(iter, "am_send", res != PYGEN_ERROR));
         return res;
diff --git a/Objects/genobject.c b/Objects/genobject.c
index 27fe15c..8cc965a 100644
--- a/Objects/genobject.c
+++ b/Objects/genobject.c
@@ -782,8 +782,7 @@ PyTypeObject PyGen_Type = {
     PyObject_GenericGetAttr,                    /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
-        Py_TPFLAGS_HAVE_AM_SEND,                /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    /* tp_flags */
     0,                                          /* tp_doc */
     (traverseproc)gen_traverse,                 /* tp_traverse */
     0,                                          /* tp_clear */
@@ -1029,8 +1028,7 @@ PyTypeObject PyCoro_Type = {
     PyObject_GenericGetAttr,                    /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
-        Py_TPFLAGS_HAVE_AM_SEND,                /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    /* tp_flags */
     0,                                          /* tp_doc */
     (traverseproc)gen_traverse,                 /* tp_traverse */
     0,                                          /* tp_clear */
@@ -1415,8 +1413,7 @@ PyTypeObject PyAsyncGen_Type = {
     PyObject_GenericGetAttr,                    /* tp_getattro */
     0,                                          /* tp_setattro */
     0,                                          /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC |
-        Py_TPFLAGS_HAVE_AM_SEND,                /* tp_flags */
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,    /* tp_flags */
     0,                                          /* tp_doc */
     (traverseproc)async_gen_traverse,           /* tp_traverse */
     0,                                          /* tp_clear */
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index badd706..42a9978 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -324,10 +324,6 @@ PyType_Modified(PyTypeObject *type)
 
        Invariants:
 
-       - Py_TPFLAGS_VALID_VERSION_TAG is never set if
-         Py_TPFLAGS_HAVE_VERSION_TAG is not set (in case of a
-         bizarre MRO, see type_mro_modified()).
-
        - before Py_TPFLAGS_VALID_VERSION_TAG can be set on a type,
          it must first be set on all super types.
 
@@ -379,9 +375,6 @@ type_mro_modified(PyTypeObject *type, PyObject *bases) {
     PyObject *mro_meth = NULL;
     PyObject *type_mro_meth = NULL;
 
-    if (!_PyType_HasFeature(type, Py_TPFLAGS_HAVE_VERSION_TAG))
-        return;
-
     if (custom) {
         mro_meth = lookup_maybe_method(
             (PyObject *)type, &PyId_mro, &unbound);
@@ -404,8 +397,7 @@ type_mro_modified(PyTypeObject *type, PyObject *bases) {
         assert(PyType_Check(b));
         cls = (PyTypeObject *)b;
 
-        if (!_PyType_HasFeature(cls, Py_TPFLAGS_HAVE_VERSION_TAG) ||
-            !PyType_IsSubtype(type, cls)) {
+        if (!PyType_IsSubtype(type, cls)) {
             goto clear;
         }
     }
@@ -413,8 +405,7 @@ type_mro_modified(PyTypeObject *type, PyObject *bases) {
  clear:
     Py_XDECREF(mro_meth);
     Py_XDECREF(type_mro_meth);
-    type->tp_flags &= ~(Py_TPFLAGS_HAVE_VERSION_TAG|
-                        Py_TPFLAGS_VALID_VERSION_TAG);
+    type->tp_flags &= ~Py_TPFLAGS_VALID_VERSION_TAG;
     type->tp_version_tag = 0; /* 0 is not a valid version tag */
 }
 
@@ -431,8 +422,6 @@ assign_version_tag(struct type_cache *cache, PyTypeObject *type)
 
     if (_PyType_HasFeature(type, Py_TPFLAGS_VALID_VERSION_TAG))
         return 1;
-    if (!_PyType_HasFeature(type, Py_TPFLAGS_HAVE_VERSION_TAG))
-        return 0;
     if (!_PyType_HasFeature(type, Py_TPFLAGS_READY))
         return 0;
 
@@ -5978,14 +5967,6 @@ type_ready_pre_checks(PyTypeObject *type)
         _PyObject_ASSERT((PyObject *)type, type->tp_call != NULL);
     }
 
-    /* Consistency check for Py_TPFLAGS_HAVE_AM_SEND - flag requires
-     * type->tp_as_async->am_send to be present.
-     */
-    if (type->tp_flags & Py_TPFLAGS_HAVE_AM_SEND) {
-        _PyObject_ASSERT((PyObject *)type, type->tp_as_async != NULL);
-        _PyObject_ASSERT((PyObject *)type, type->tp_as_async->am_send != NULL);
-    }
-
     /* Consistency checks for pattern matching
      * Py_TPFLAGS_SEQUENCE and Py_TPFLAGS_MAPPING are mutually exclusive */
     _PyObject_ASSERT((PyObject *)type, (type->tp_flags & COLLECTION_FLAGS) != COLLECTION_FLAGS);