[3.11] gh-113566: Fix asyncio segfault during interpreter finalization (#113578)

Author: gvanrossum

Misc/NEWS.d/next/Core and Builtins/2023-12-29-16-55-12.gh-issue-113566.grGQEg.rst

@@ -0,0 +1,2 @@
+Fix a 3.11-specific crash when the ``repr`` of a :class:`~asyncio.Future` is
+requested after the module has already been garbage-collected.

Modules/_asynciomodule.c

@@ -1377,6 +1377,9 @@ static PyObject *
 FutureObj_repr(FutureObj *fut)
 {
     ENSURE_FUTURE_ALIVE(fut)
+    if (asyncio_future_repr_func == NULL) {
+        return PyUnicode_FromFormat("<Future at %p>", fut);
+    }
     return PyObject_CallOneArg(asyncio_future_repr_func, (PyObject *)fut);
 }