diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py index 634be9062d63394072e665ac971974ba0b1e5fe0..2fd57822726e56c9254f40070e7d17e01e61d556 100644 --- a/Lib/test/test_typing.py +++ b/Lib/test/test_typing.py @@ -3644,6 +3644,35 @@ def test_subclass_special_form(self): class Foo(obj): pass + def test_complex_subclasses(self): + T_co = TypeVar("T_co", covariant=True) + + class Base(Generic[T_co]): + ... + + T = TypeVar("T") + + # see gh-94607: this fails in that bug + class Sub(Base, Generic[T]): + ... + + def test_parameter_detection(self): + self.assertEqual(List[T].__parameters__, (T,)) + self.assertEqual(List[List[T]].__parameters__, (T,)) + class A: + __parameters__ = (T,) + # Bare classes should be skipped + for a in (List, list): + for b in (A, int, TypeVar, TypeVarTuple, ParamSpec, types.GenericAlias, types.UnionType): + with self.subTest(generic=a, sub=b): + with self.assertRaisesRegex(TypeError, '.* is not a generic class'): + a[b][str] + # Duck-typing anything that looks like it has __parameters__. + # These tests are optional and failure is okay. + self.assertEqual(List[A()].__parameters__, (T,)) + # C version of GenericAlias + self.assertEqual(list[A()].__parameters__, (T,)) + class ClassVarTests(BaseTestCase): def test_basics(self): diff --git a/Lib/typing.py b/Lib/typing.py index 1ebc3ce1f64bd61e5fa1ca488a93a0926d8e3625..31269273a5c0d324c0fc07a9deb3d1ebd7df0c96 100644 --- a/Lib/typing.py +++ b/Lib/typing.py @@ -250,6 +250,9 @@ def _collect_parameters(args): """ parameters = [] for t in args: + # We don't want __parameters__ descriptor of a bare Python class. + if isinstance(t, type): + continue if hasattr(t, '__typing_subst__'): if t not in parameters: parameters.append(t) diff --git a/Misc/NEWS.d/next/Library/2022-07-06-16-01-08.gh-issue-94607.Q6RYfz.rst b/Misc/NEWS.d/next/Library/2022-07-06-16-01-08.gh-issue-94607.Q6RYfz.rst new file mode 100644 index 0000000000000000000000000000000000000000..3bbb9172f26195f962a4d40d348f589e8f2b94e1 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2022-07-06-16-01-08.gh-issue-94607.Q6RYfz.rst @@ -0,0 +1,2 @@ +Fix subclassing complex generics with type variables in :mod:`typing`. Previously an error message saying ``Some type variables ... are not listed in Generic[...]`` was shown. +:mod:`typing` no longer populates ``__parameters__`` with the ``__parameters__`` of a Python class. diff --git a/Objects/genericaliasobject.c b/Objects/genericaliasobject.c index b2636d5475dbb952d4bca5b55862c5f1a487e16c..19f011fd3a7437f2d00aa98767b4860e089230fe 100644 --- a/Objects/genericaliasobject.c +++ b/Objects/genericaliasobject.c @@ -219,6 +219,10 @@ _Py_make_parameters(PyObject *args) for (Py_ssize_t iarg = 0; iarg < nargs; iarg++) { PyObject *t = PyTuple_GET_ITEM(args, iarg); PyObject *subst; + // We don't want __parameters__ descriptor of a bare Python class. + if (PyType_Check(t)) { + continue; + } if (_PyObject_LookupAttr(t, &_Py_ID(__typing_subst__), &subst) < 0) { Py_DECREF(parameters); return NULL;