[3.13] gh-132011: Fix crash on invalid CALL_LIST_APPEND deoptimization (GH-132018)

Lib/test/test_list.py

@@ -1,6 +1,8 @@
 import sys
+import textwrap
 from test import list_tests
 from test.support import cpython_only
+from test.support.script_helper import assert_python_ok
 import pickle
 import unittest
 
@@ -309,5 +311,25 @@ def test_tier2_invalidates_iterator(self):
             a.append(4)
             self.assertEqual(list(it), [])
 
+    def test_deopt_from_append_list(self):
+        # gh-132011: it used to crash, because
+        # of `CALL_LIST_APPEND` specialization failure.
+        code = textwrap.dedent("""
+            l = []
+            def lappend(l, x, y):
+                l.append((x, y))
+            for x in range(3):
+                lappend(l, None, None)
+            try:
+                lappend(list, None, None)
+            except TypeError:
+                pass
+            else:
+                raise AssertionError
+        """)
+
+        rc, _, _ = assert_python_ok("-c", code)
+        self.assertEqual(rc, 0)
+
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Core_and_Builtins/2025-04-02-17-47-14.gh-issue-132011.dNh64H.rst

@@ -0,0 +1 @@
+Fix crash when calling :meth:`!list.append` as an unbound method.

Python/bytecodes.c

@@ -3631,7 +3631,7 @@ dummy_func(
             assert(oparg == 1);
             PyInterpreterState *interp = tstate->interp;
             DEOPT_IF(callable != interp->callable_cache.list_append);
-            assert(self != NULL);
+            DEOPT_IF(self == NULL);
             DEOPT_IF(!PyList_Check(self));
             STAT_INC(CALL, hit);
             if (_PyList_AppendTakeRef((PyListObject *)self, arg) < 0) {