8000 bpo-44263: Py_TPFLAGS_HAVE_GC requires tp_traverse (GH-26463) · python/cpython@ee76375 · GitHub
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bpo-44263: Py_TPFLAGS_HAVE_GC requires tp_traverse (GH-26463)
The PyType_Ready() function now raises an error if a type is defined with the Py_TPFLAGS_HAVE_GC flag set but has no traverse function (PyTypeObject.tp_traverse).
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3 files changed

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-3
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3 files changed

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‎Doc/whatsnew/3.11.rst

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@@ -144,6 +144,11 @@ New Features
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Porting to Python 3.11
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----------------------
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* The :c:func:`PyType_Ready` function now raises an error if a type is defined
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with the :const:`Py_TPFLAGS_HAVE_GC` flag set but has no traverse function
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(:c:member:`PyTypeObject.tp_traverse`).
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(Contributed by Victor Stinner in :issue:`44263`.)
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Deprecated
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----------
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@@ -180,4 +185,4 @@ Removed
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parameter of functions :func:`~gettext.translation` and
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:func:`~gettext.install` are also removed, since they are only used for
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the ``l*gettext()`` functions.
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(Contributed by Dong-hee Na and Serhiy Storchaka in :issue:`44235`.)
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(Contributed by Dong-hee Na and Serhiy Storchaka in :issue:`44235`.)

‎Misc/NEWS.d/next/C API/2021-05-31-11-31-13.bpo-44263.8mIOfV.rst

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@@ -0,0 +1,4 @@
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The :c:func:`PyType_Ready` function now raises an error if a type is defined
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with the :const:`Py_TPFLAGS_HAVE_GC` flag set but has no traverse function
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(:c:member:`PyTypeObject.tp_traverse`).
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Patch by Victor Stinner.

‎Objects/typeobject.c

Lines changed: 30 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -158,6 +158,12 @@ _PyType_CheckConsistency(PyTypeObject *type)
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CHECK(!(type->tp_flags & Py_TPFLAGS_READYING));
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CHECK(type->tp_dict != NULL);
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if (type->tp_flags & Py_TPFLAGS_HAVE_GC) {
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// bpo-44263: tp_traverse is required if Py_TPFLAGS_HAVE_GC is set.
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// Note: tp_clear is optional.
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CHECK(type->tp_traverse != NULL);
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}
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if (type->tp_flags & Py_TPFLAGS_DISALLOW_INSTANTIATION) {
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CHECK(type->tp_new == NULL);
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CHECK(_PyDict_ContainsId(type->tp_dict, &PyId___new__) == 0);
@@ -3607,6 +3613,7 @@ PyType_FromModuleAndSpec(PyObject *module, PyType_Spec *spec, PyObject *bases)
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}
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}
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assert(_PyType_CheckConsistency(type));
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return (PyObject*)res;
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fail:
@@ -5944,7 +5951,7 @@ static int add_tp_new_wrapper(PyTypeObject *type);
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#define COLLECTION_FLAGS (Py_TPFLAGS_SEQUENCE | Py_TPFLAGS_MAPPING)
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static int
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type_ready_checks(PyTypeObject *type)
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type_ready_pre_checks(PyTypeObject *type)
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{
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/* Consistency checks for PEP 590:
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* - Py_TPFLAGS_METHOD_DESCRIPTOR requires tp_descr_get
@@ -6305,10 +6312,28 @@ type_ready_set_new(PyTypeObject *type)
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}
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static int
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type_ready_post_checks(PyTypeObject *type)
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{
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// bpo-44263: tp_traverse is required if Py_TPFLAGS_HAVE_GC is set.
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// Note: tp_clear is optional.
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if (type->tp_flags & Py_TPFLAGS_HAVE_GC
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&& type->tp_traverse == NULL)
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{
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PyErr_Format(PyExc_SystemError,
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"type %s has the Py_TPFLAGS_HAVE_GC flag "
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"but has no traverse function",
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type->tp_name);
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return -1;
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}
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return 0;
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}
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static int
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type_ready(PyTypeObject *type)
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{
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if (type_ready_checks(type) < 0) {
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if (type_ready_pre_checks(type) < 0) {
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return -1;
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}
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@@ -6346,6 +6371,9 @@ type_ready(PyTypeObject *type)
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if (type_ready_add_subclasses(type) < 0) {
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return -1;
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}
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if (type_ready_post_checks(type) < 0) {
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return -1;
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}
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return 0;
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}
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