Message401854
The fact that the error indicator may be set during tp_dealloc is somewhat well known (https://github.com/posborne/dbus-python/blob/fef4bccfc535c6c2819e3f15384600d7bc198bc5/_dbus_bindings/conn.c#L387) but it's not documented in the official manual. We should document it.
A simple suggested patch:
diff --git a/Doc/c-api/typeobj.rst b/Doc/c-api/typeobj.rst
index b17fb22b69..e7c9b13646 100644
--- a/Doc/c-api/typeobj.rst
+++ b/Doc/c-api/typeobj.rst
@@ -668,6 +668,20 @@ and :c:type:`PyType_Type` effectively act as defaults.)
:c:func:`PyObject_GC_Del` if the instance was allocated using
:c:func:`PyObject_GC_New` or :c:func:`PyObject_GC_NewVar`.
+ If you may call functions that may set the error indicator, you must
+ use :c:func:`PyErr_Fetch` and :c:func:`PyErr_Restore` to ensure you
+ don't clobber a preexisting error indicator (the deallocation could
+ have occurred while processing a different error):
+
+ .. code-block:: c
+
+ static void foo_dealloc(foo_object *self) {
+ PyObject *et, *ev, *etb;
+ PyErr_Fetch(&et, &ev, &etb);
+ ...
+ PyErr_Restore(et, ev, etb);
+ }
+
Finally, if the type is heap allocated (:const:`Py_TPFLAGS_HEAPTYPE`), the
deallocator should decrement the reference count for its type object after
calling the type deallocator. In order to avoid dangling pointers, the |
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Date |
User |
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2021-09-15 16:47:23 | ezyang | set | recipients:
+ ezyang, docs@python |
2021-09-15 16:47:23 | ezyang | set | messageid: <1631724443.4.0.588312077609.issue45210@roundup.psfhosted.org> |
2021-09-15 16:47:23 | ezyang | link | issue45210 messages |
2021-09-15 16:47:23 | ezyang | create | |
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