bpo-42195: Disallow isinstance/issubclass for subclasses of genericaliases in Union (GH-24059)
Previously this didn't raise an error. Now it will:
```python
from collections.abc import Callable
isinstance(int, list | Callable[..., str])
```
Also added tests in Union since there were previously none for stuff like ``isinstance(list, list | list[int])`` either.
Backport to 3.9 not required.
Automerge-Triggered-By: GH:gvanrossum
diff --git a/Objects/unionobject.c b/Objects/unionobject.c
index 32aa507..0535036 100644
--- a/Objects/unionobject.c
+++ b/Objects/unionobject.c
@@ -34,7 +34,7 @@ is_generic_alias_in_args(PyObject *args) {
Py_ssize_t nargs = PyTuple_GET_SIZE(args);
for (Py_ssize_t iarg = 0; iarg < nargs; iarg++) {
PyObject *arg = PyTuple_GET_ITEM(args, iarg);
- if (Py_TYPE(arg) == &Py_GenericAliasType) {
+ if (PyObject_TypeCheck(arg, &Py_GenericAliasType)) {
return 0;
}
}