From 432bf31327c6b9647acb8bdb0eac2d392fd9f60a Mon Sep 17 00:00:00 2001
From: Petr Viktorin <encukou@gmail.com>
Date: Fri, 13 Sep 2024 13:18:49 +0200
Subject: gh-123909: PyType_From*: Disallow metaclasses with custom tp_new
(GH-123947)
---
Doc/c-api/type.rst | 24 ++++++++++----
Lib/test/test_capi/test_misc.py | 12 ++-----
.../2024-09-10-16-54-27.gh-issue-123909.CTGxDR.rst | 3 ++
Objects/typeobject.c | 38 ++++++----------------
4 files changed, 34 insertions(+), 43 deletions(-)
create mode 100644 Misc/NEWS.d/next/C_API/2024-09-10-16-54-27.gh-issue-123909.CTGxDR.rst
diff --git a/Doc/c-api/type.rst b/Doc/c-api/type.rst
index 0cae5c0..fa04d6c 100644
--- a/Doc/c-api/type.rst
+++ b/Doc/c-api/type.rst
@@ -345,8 +345,12 @@ The following functions and structs are used to create
The :c:member:`~PyTypeObject.tp_new` of the metaclass is *ignored*.
which may result in incomplete initialization.
Creating classes whose metaclass overrides
- :c:member:`~PyTypeObject.tp_new` is deprecated and in Python 3.14+ it
- will be no longer allowed.
+ :c:member:`~PyTypeObject.tp_new` is deprecated.
+
+ .. versionchanged:: 3.14
+
+ Creating classes whose metaclass overrides
+ :c:member:`~PyTypeObject.tp_new` is no longer allowed.
.. c:function:: PyObject* PyType_FromSpecWithBases(PyType_Spec *spec, PyObject *bases)
@@ -362,8 +366,12 @@ The following functions and structs are used to create
The :c:member:`~PyTypeObject.tp_new` of the metaclass is *ignored*.
which may result in incomplete initialization.
Creating classes whose metaclass overrides
- :c:member:`~PyTypeObject.tp_new` is deprecated and in Python 3.14+ it
- will be no longer allowed.
+ :c:member:`~PyTypeObject.tp_new` is deprecated.
+
+ .. versionchanged:: 3.14
+
+ Creating classes whose metaclass overrides
+ :c:member:`~PyTypeObject.tp_new` is no longer allowed.
.. c:function:: PyObject* PyType_FromSpec(PyType_Spec *spec)
@@ -378,8 +386,12 @@ The following functions and structs are used to create
The :c:member:`~PyTypeObject.tp_new` of the metaclass is *ignored*.
which may result in incomplete initialization.
Creating classes whose metaclass overrides
- :c:member:`~PyTypeObject.tp_new` is deprecated and in Python 3.14+ it
- will be no longer allowed.
+ :c:member:`~PyTypeObject.tp_new` is deprecated.
+
+ .. versionchanged:: 3.14
+
+ Creating classes whose metaclass overrides
+ :c:member:`~PyTypeObject.tp_new` is no longer allowed.
.. raw:: html
diff --git a/Lib/test/test_capi/test_misc.py b/Lib/test/test_capi/test_misc.py
index d50217b..18392c4 100644
--- a/Lib/test/test_capi/test_misc.py
+++ b/Lib/test/test_capi/test_misc.py
@@ -722,22 +722,16 @@ class CAPITest(unittest.TestCase):
with self.assertRaisesRegex(TypeError, msg):
t = _testcapi.pytype_fromspec_meta(metaclass)
- def test_heaptype_with_custom_metaclass_deprecation(self):
+ def test_heaptype_base_with_custom_metaclass(self):
metaclass = _testcapi.HeapCTypeMetaclassCustomNew
- # gh-103968: a metaclass with custom tp_new is deprecated, but still
- # allowed for functions that existed in 3.11
- # (PyType_FromSpecWithBases is used here).
class Base(metaclass=metaclass):
pass
# Class creation from C
- with warnings_helper.check_warnings(
- ('.* _testcapi.Subclass .* custom tp_new.*in Python 3.14.*', DeprecationWarning),
- ):
+ msg = "Metaclasses with custom tp_new are not supported."
+ with self.assertRaisesRegex(TypeError, msg):
sub = _testcapi.make_type_with_base(Base)
- self.assertTrue(issubclass(sub, Base))
- self.assertIsInstance(sub, metaclass)
def test_multiple_inheritance_ctypes_with_weakref_or_dict(self):
for weakref_cls in (_testcapi.HeapCTypeWithWeakref,
diff --git a/Misc/NEWS.d/next/C_API/2024-09-10-16-54-27.gh-issue-123909.CTGxDR.rst b/Misc/NEWS.d/next/C_API/2024-09-10-16-54-27.gh-issue-123909.CTGxDR.rst
new file mode 100644
index 0000000..b7a4913
--- /dev/null
+++ b/Misc/NEWS.d/next/C_API/2024-09-10-16-54-27.gh-issue-123909.CTGxDR.rst
@@ -0,0 +1,3 @@
+:c:func:`PyType_FromSpec`, :c:func:`PyType_FromSpecWithBases` and
+:c:func:`PyType_FromModuleAndSpec` will now fail if the metaclass of the new
+type has custom :c:member:`~PyTypeObject.tp_new`.
diff --git a/Objects/typeobject.c b/Objects/typeobject.c
index a6483f7..28edd80 100644
--- a/Objects/typeobject.c
+++ b/Objects/typeobject.c
@@ -4668,10 +4668,10 @@ special_offset_from_member(
return -1;
}
-static PyObject *
-_PyType_FromMetaclass_impl(
+PyObject *
+PyType_FromMetaclass(
PyTypeObject *metaclass, PyObject *module,
- PyType_Spec *spec, PyObject *bases_in, int _allow_tp_new)
+ PyType_Spec *spec, PyObject *bases_in)
{
/* Invariant: A non-NULL value in one of these means this function holds
* a strong reference or owns allocated memory.
@@ -4848,21 +4848,10 @@ _PyType_FromMetaclass_impl(
goto finally;
}
if (metaclass->tp_new && metaclass->tp_new != PyType_Type.tp_new) {
- if (_allow_tp_new) {
- if (PyErr_WarnFormat(
- PyExc_DeprecationWarning, 1,
- "Type %s uses PyType_Spec with a metaclass that has custom "
- "tp_new. This is deprecated and will no longer be allowed in "
- "Python 3.14.", spec->name) < 0) {
- goto finally;
- }
- }
- else {
- PyErr_SetString(
- PyExc_TypeError,
- "Metaclasses with custom tp_new are not supported.");
- goto finally;
- }
+ PyErr_SetString(
+ PyExc_TypeError,
+ "Metaclasses with custom tp_new are not supported.");
+ goto finally;
}
/* Calculate best base, and check that all bases are type objects */
@@ -5110,28 +5099,21 @@ _PyType_FromMetaclass_impl(
}
PyObject *
-PyType_FromMetaclass(PyTypeObject *metaclass, PyObject *module,
- PyType_Spec *spec, PyObject *bases_in)
-{
- return _PyType_FromMetaclass_impl(metaclass, module, spec, bases_in, 0);
-}
-
-PyObject *
PyType_FromModuleAndSpec(PyObject *module, PyType_Spec *spec, PyObject *bases)
{
- return _PyType_FromMetaclass_impl(NULL, module, spec, bases, 1);
+ return PyType_FromMetaclass(NULL, module, spec, bases);
}
PyObject *
PyType_FromSpecWithBases(PyType_Spec *spec, PyObject *bases)
{
- return _PyType_FromMetaclass_impl(NULL, NULL, spec, bases, 1);
+ return PyType_FromMetaclass(NULL, NULL, spec, bases);
}
PyObject *
PyType_FromSpec(PyType_Spec *spec)
{
- return _PyType_FromMetaclass_impl(NULL, NULL, spec, NULL, 1);
+ return PyType_FromMetaclass(NULL, NULL, spec, NULL);
}
PyObject *
--
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