https://github.com/python/cpython/commit/8441b263af964f353bf02d56c32a4fc547cdc330
commit: 8441b263af964f353bf02d56c32a4fc547cdc330
branch: main
author: Edward Z. Yang <ezy...@mit.edu>
committer: vstinner <vstin...@python.org>
date: 2025-06-09T08:56:32Z
summary:
bpo-45210: Document that error indicator may be set in tp_dealloc (#28358)
Signed-off-by: Edward Z. Yang <ezy...@fb.com>
Signed-off-by: Edward Z. Yang <ezy...@meta.com>
Co-authored-by: Victor Stinner <vstin...@python.org>
files:
A Misc/NEWS.d/next/Documentation/2021-09-15-13-07-25.bpo-45210.RtGk7i.rst
M Doc/c-api/typeobj.rst
diff --git a/Doc/c-api/typeobj.rst b/Doc/c-api/typeobj.rst
index 91046c0e6f18ae..af2bead3bb5004 100644
--- a/Doc/c-api/typeobj.rst
+++ b/Doc/c-api/typeobj.rst
@@ -686,6 +686,26 @@ and :c:data:`PyType_Type` effectively act as defaults.)
instance, and call the type's :c:member:`~PyTypeObject.tp_free` function to
free the object itself.
+ If you may call functions that may set the error indicator, you must use
+ :c:func:`PyErr_GetRaisedException` and :c:func:`PyErr_SetRaisedException`
+ 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;
+ PyObject *exc = PyErr_GetRaisedException();
+ ...
+ PyErr_SetRaisedException(exc);
+ }
+
+ The dealloc handler itself must not raise an exception; if it hits an error
+ case it should call :c:func:`PyErr_FormatUnraisable` to log (and clear) an
+ unraisable exception.
+
No guarantees are made about when an object is destroyed, except:
* Python will destroy an object immediately or some time after the final
diff --git
a/Misc/NEWS.d/next/Documentation/2021-09-15-13-07-25.bpo-45210.RtGk7i.rst
b/Misc/NEWS.d/next/Documentation/2021-09-15-13-07-25.bpo-45210.RtGk7i.rst
new file mode 100644
index 00000000000000..ce3eba154ba6aa
--- /dev/null
+++ b/Misc/NEWS.d/next/Documentation/2021-09-15-13-07-25.bpo-45210.RtGk7i.rst
@@ -0,0 +1,2 @@
+Document that error indicator may be set in tp_dealloc, and how to avoid
+clobbering it.
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