From 2e95d830ee5ffcee36d5fedf9e7c5f37d51819a9 Mon Sep 17 00:00:00 2001 From: Serhiy Storchaka Date: Fri, 27 Jun 2025 14:35:55 +0300 Subject: [PATCH] [3.13] gh-78465: Fix error message for cls.__new__(cls, ...) where cls is not instantiable (GH-135981) Previous error message suggested to use cls.__new__(), which obviously does not work. Now the error message is the same as for cls(...). (cherry picked from commit c45f4f3ebe34529a8db3a7918e8dd2e9f7ce8e86) Co-authored-by: Serhiy Storchaka --- Lib/test/support/__init__.py | 1 + Lib/test/test_sys.py | 7 +------ .../2025-06-26-15-25-51.gh-issue-78465.MbDN8X.rst | 2 ++ Objects/typeobject.c | 5 +++++ 4 files changed, 9 insertions(+), 6 deletions(-) create mode 100644 Misc/NEWS.d/next/Core and Builtins/2025-06-26-15-25-51.gh-issue-78465.MbDN8X.rst diff --git a/Lib/test/support/__init__.py b/Lib/test/support/__init__.py index c2b407159a57ec..8bed02a158989a 100644 --- a/Lib/test/support/__init__.py +++ b/Lib/test/support/__init__.py @@ -2269,6 +2269,7 @@ def check_disallow_instantiation(testcase, tp, *args, **kwds): qualname = f"{name}" msg = f"cannot create '{re.escape(qualname)}' instances" testcase.assertRaisesRegex(TypeError, msg, tp, *args, **kwds) + testcase.assertRaisesRegex(TypeError, msg, tp.__new__, tp, *args, **kwds) def get_recursion_depth(): """Get the recursion depth of the caller function. diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py index 72d51361e0b4d1..6b37094ed5fc32 100644 --- a/Lib/test/test_sys.py +++ b/Lib/test/test_sys.py @@ -894,12 +894,7 @@ def test_sys_flags(self): def assert_raise_on_new_sys_type(self, sys_attr): # Users are intentionally prevented from creating new instances of # sys.flags, sys.version_info, and sys.getwindowsversion. - arg = sys_attr - attr_type = type(sys_attr) - with self.assertRaises(TypeError): - attr_type(arg) - with self.assertRaises(TypeError): - attr_type.__new__(attr_type, arg) + support.check_disallow_instantiation(self, type(sys_attr), sys_attr) def test_sys_flags_no_instantiation(self): self.assert_raise_on_new_sys_type(sys.flags) diff --git a/Misc/NEWS.d/next/Core and Builtins/2025-06-26-15-25-51.gh-issue-78465.MbDN8X.rst b/Misc/NEWS.d/next/Core and Builtins/2025-06-26-15-25-51.gh-issue-78465.MbDN8X.rst new file mode 100644 index 00000000000000..99734d63c5d87e --- /dev/null +++ b/Misc/NEWS.d/next/Core and Builtins/2025-06-26-15-25-51.gh-issue-78465.MbDN8X.rst @@ -0,0 +1,2 @@ +Fix error message for ``cls.__new__(cls, ...)`` where ``cls`` is not +instantiable builtin or extension type (with ``tp_new`` set to ``NULL``). diff --git a/Objects/typeobject.c b/Objects/typeobject.c index 2b63c1bbfab337..2dface4b758224 100644 --- a/Objects/typeobject.c +++ b/Objects/typeobject.c @@ -9087,6 +9087,11 @@ tp_new_wrapper(PyObject *self, PyObject *args, PyObject *kwds) /* If staticbase is NULL now, it is a really weird type. In the spirit of backwards compatibility (?), just shut up. */ if (staticbase && staticbase->tp_new != type->tp_new) { + if (staticbase->tp_new == NULL) { + PyErr_Format(PyExc_TypeError, + "cannot create '%s' instances", subtype->tp_name); + return NULL; + } PyErr_Format(PyExc_TypeError, "%s.__new__(%s) is not safe, use %s.__new__()", type->tp_name,