https://github.com/python/cpython/commit/4443110c3409ecba9f0fd49495d039030cb7ed58
commit: 4443110c3409ecba9f0fd49495d039030cb7ed58
branch: main
author: Jelle Zijlstra <jelle.zijls...@gmail.com>
committer: JelleZijlstra <jelle.zijls...@gmail.com>
date: 2025-05-25T08:38:18-07:00
summary:
gh-133778: Fix setting `__annotations__` under PEP 563 (#133794)
files:
A
Misc/NEWS.d/next/Core_and_Builtins/2025-05-09-18-11-21.gh-issue-133778.pWEV3t.rst
M Lib/test/test_type_annotations.py
M Objects/typeobject.c
diff --git a/Lib/test/test_type_annotations.py
b/Lib/test/test_type_annotations.py
index 2c886bb6d362fa..c66cb058552643 100644
--- a/Lib/test/test_type_annotations.py
+++ b/Lib/test/test_type_annotations.py
@@ -498,6 +498,28 @@ def f(x: int) -> int: pass
self.assertEqual(f.__annotate__(annotationlib.Format.VALUE), annos)
self.assertEqual(f.__annotations__, annos)
+ def test_set_annotations(self):
+ function_code = textwrap.dedent("""
+ def f(x: int):
+ pass
+ """)
+ class_code = textwrap.dedent("""
+ class f:
+ x: int
+ """)
+ for future in (False, True):
+ for label, code in (("function", function_code), ("class",
class_code)):
+ with self.subTest(future=future, label=label):
+ if future:
+ code = "from __future__ import annotations\n" + code
+ ns = run_code(code)
+ f = ns["f"]
+ anno = "int" if future else int
+ self.assertEqual(f.__annotations__, {"x": anno})
+
+ f.__annotations__ = {"x": str}
+ self.assertEqual(f.__annotations__, {"x": str})
+
def test_name_clash_with_format(self):
# this test would fail if __annotate__'s parameter was called "format"
# during symbol table construction
diff --git
a/Misc/NEWS.d/next/Core_and_Builtins/2025-05-09-18-11-21.gh-issue-133778.pWEV3t.rst
b/Misc/NEWS.d/next/Core_and_Builtins/2025-05-09-18-11-21.gh-issue-133778.pWEV3t.rst
new file mode 100644
index 00000000000000..6eb6881213c434
--- /dev/null
+++
b/Misc/NEWS.d/next/Core_and_Builtins/2025-05-09-18-11-21.gh-issue-133778.pWEV3t.rst
@@ -0,0 +1,2 @@
+Fix bug where assigning to the :attr:`~type.__annotations__` attributes of
+classes defined under ``from __future__ import annotations`` had no effect.
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index a7ab69fef4c721..ee09289425b91a 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -2065,19 +2065,46 @@ type_set_annotations(PyObject *tp, PyObject *value,
void *Py_UNUSED(closure))
return -1;
}
- int result;
PyObject *dict = PyType_GetDict(type);
- if (value != NULL) {
- /* set */
- result = PyDict_SetItem(dict, &_Py_ID(__annotations_cache__), value);
- } else {
- /* delete */
- result = PyDict_Pop(dict, &_Py_ID(__annotations_cache__), NULL);
- if (result == 0) {
- PyErr_SetString(PyExc_AttributeError, "__annotations__");
+ int result = PyDict_ContainsString(dict, "__annotations__");
+ if (result < 0) {
+ Py_DECREF(dict);
+ return -1;
+ }
+ if (result) {
+ // If __annotations__ is currently in the dict, we update it,
+ if (value != NULL) {
+ result = PyDict_SetItem(dict, &_Py_ID(__annotations__), value);
+ } else {
+ result = PyDict_Pop(dict, &_Py_ID(__annotations__), NULL);
+ if (result == 0) {
+ // Somebody else just deleted it?
+ PyErr_SetString(PyExc_AttributeError, "__annotations__");
+ Py_DECREF(dict);
+ return -1;
+ }
+ }
+ if (result < 0) {
Py_DECREF(dict);
return -1;
}
+ // Also clear __annotations_cache__ just in case.
+ result = PyDict_Pop(dict, &_Py_ID(__annotations_cache__), NULL);
+ }
+ else {
+ // Else we update only __annotations_cache__.
+ if (value != NULL) {
+ /* set */
+ result = PyDict_SetItem(dict, &_Py_ID(__annotations_cache__),
value);
+ } else {
+ /* delete */
+ result = PyDict_Pop(dict, &_Py_ID(__annotations_cache__), NULL);
+ if (result == 0) {
+ PyErr_SetString(PyExc_AttributeError, "__annotations__");
+ Py_DECREF(dict);
+ return -1;
+ }
+ }
}
if (result < 0) {
Py_DECREF(dict);
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