From f93b57848ef4bd6f1f6292bf9a0ebbd528e7b5f8 Mon Sep 17 00:00:00 2001
From: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Date: Fri, 23 Jan 2026 06:43:32 -0800
Subject: [PATCH 1/2] gh-144169: Fix three crashes in AST objects with non-str
 kwargs

---
 Lib/test/test_ast/test_ast.py                 | 26 +++++++++++++++++++
 ...-01-23-06-43-21.gh-issue-144169.LFy9yi.rst |  2 ++
 Parser/asdl_c.py                              |  6 ++---
 Python/Python-ast.c                           |  6 ++---
 4 files changed, 34 insertions(+), 6 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2026-01-23-06-43-21.gh-issue-144169.LFy9yi.rst

diff --git a/Lib/test/test_ast/test_ast.py b/Lib/test/test_ast/test_ast.py
index 3917407fb37d9e..7a78aa7466222e 100644
--- a/Lib/test/test_ast/test_ast.py
+++ b/Lib/test/test_ast/test_ast.py
@@ -1443,6 +1443,12 @@ def test_replace_reject_unknown_instance_fields(self):
         self.assertIs(node.ctx, context)
         self.assertRaises(AttributeError, getattr, node, 'unknown')
 
+    def test_replace_non_str_kwarg(self):
+        node = ast.Name(id="x")
+        with self.assertRaisesRegex(TypeError, "got an unexpected keyword argument <object object"):
+            node.__replace__(**{object(): "y"})
+
+
 class ASTHelpers_Test(unittest.TestCase):
     maxDiff = None
 
@@ -3304,6 +3310,26 @@ class _AllFieldTypes(ast.AST):
         self.assertIs(obj.a, None)
         self.assertEqual(obj.b, [])
 
+    def test_non_str_kwarg(self):
+        with (
+            self.assertRaises(TypeError),
+            self.assertWarnsRegex(DeprecationWarning, "got an unexpected keyword argument <object object"),
+        ):
+            ast.Name(**{object(): 'y'})
+
+        class FakeStr:
+            def __init__(self, value):
+                self.value = value
+
+            def __hash__(self):
+                return hash(self.value)
+
+            def __eq__(self, other):
+                return isinstance(other, str) and self.value == other
+
+        with self.assertRaisesRegex(TypeError, "got multiple values for argument"):
+            ast.Name("x", **{FakeStr('id'): 'y'})
+
 
 @support.cpython_only
 class ModuleStateTests(unittest.TestCase):
diff --git a/Misc/NEWS.d/next/Library/2026-01-23-06-43-21.gh-issue-144169.LFy9yi.rst b/Misc/NEWS.d/next/Library/2026-01-23-06-43-21.gh-issue-144169.LFy9yi.rst
new file mode 100644
index 00000000000000..e2ef3d7c051d14
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-01-23-06-43-21.gh-issue-144169.LFy9yi.rst
@@ -0,0 +1,2 @@
+Fix three crashes when non-string keyword arguments are supplied to objects
+in the :mod:`ast` module.
diff --git a/Parser/asdl_c.py b/Parser/asdl_c.py
index 3e252cbc4883d1..5ad20d49fa4b31 100755
--- a/Parser/asdl_c.py
+++ b/Parser/asdl_c.py
@@ -942,7 +942,7 @@ def visitModule(self, mod):
                 }
                 if (p == 0) {
                     PyErr_Format(PyExc_TypeError,
-                        "%.400s got multiple values for argument '%U'",
+                        "%.400s got multiple values for argument %R",
                         Py_TYPE(self)->tp_name, key);
                     res = -1;
                     goto cleanup;
@@ -965,7 +965,7 @@ def visitModule(self, mod):
                 else if (contains == 0) {
                     if (PyErr_WarnFormat(
                         PyExc_DeprecationWarning, 1,
-                        "%.400s.__init__ got an unexpected keyword argument '%U'. "
+                        "%.400s.__init__ got an unexpected keyword argument %R. "
                         "Support for arbitrary keyword arguments is deprecated "
                         "and will be removed in Python 3.15.",
                         Py_TYPE(self)->tp_name, key
@@ -1207,7 +1207,7 @@ def visitModule(self, mod):
             if (rc == 0) {
                 PyErr_Format(PyExc_TypeError,
                              "%.400s.__replace__ got an unexpected keyword "
-                             "argument '%U'.", Py_TYPE(self)->tp_name, key);
+                             "argument %R.", Py_TYPE(self)->tp_name, key);
                 Py_DECREF(expecting);
                 return -1;
             }
diff --git a/Python/Python-ast.c b/Python/Python-ast.c
index 79608dee9bfac2..1cc88dc179e120 100644
--- a/Python/Python-ast.c
+++ b/Python/Python-ast.c
@@ -5226,7 +5226,7 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
                 }
                 if (p == 0) {
                     PyErr_Format(PyExc_TypeError,
-                        "%.400s got multiple values for argument '%U'",
+                        "%.400s got multiple values for argument %R",
                         Py_TYPE(self)->tp_name, key);
                     res = -1;
                     goto cleanup;
@@ -5249,7 +5249,7 @@ ast_type_init(PyObject *self, PyObject *args, PyObject *kw)
                 else if (contains == 0) {
                     if (PyErr_WarnFormat(
                         PyExc_DeprecationWarning, 1,
-                        "%.400s.__init__ got an unexpected keyword argument '%U'. "
+                        "%.400s.__init__ got an unexpected keyword argument %R. "
                         "Support for arbitrary keyword arguments is deprecated "
                         "and will be removed in Python 3.15.",
                         Py_TYPE(self)->tp_name, key
@@ -5491,7 +5491,7 @@ ast_type_replace_check(PyObject *self,
             if (rc == 0) {
                 PyErr_Format(PyExc_TypeError,
                              "%.400s.__replace__ got an unexpected keyword "
-                             "argument '%U'.", Py_TYPE(self)->tp_name, key);
+                             "argument %R.", Py_TYPE(self)->tp_name, key);
                 Py_DECREF(expecting);
                 return -1;
             }

From ae7668b2fd9e3fd7ccb8bb0ec75a6fea4e577a69 Mon Sep 17 00:00:00 2001
From: Jelle Zijlstra <jelle.zijlstra@gmail.com>
Date: Fri, 23 Jan 2026 20:06:18 -0800
Subject: [PATCH 2/2] Apply suggestions from code review

Co-authored-by: Victor Stinner <vstinner@python.org>
---
 Lib/test/test_ast/test_ast.py | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/Lib/test/test_ast/test_ast.py b/Lib/test/test_ast/test_ast.py
index 7a78aa7466222e..c5f42cb7888c08 100644
--- a/Lib/test/test_ast/test_ast.py
+++ b/Lib/test/test_ast/test_ast.py
@@ -1445,7 +1445,8 @@ def test_replace_reject_unknown_instance_fields(self):
 
     def test_replace_non_str_kwarg(self):
         node = ast.Name(id="x")
-        with self.assertRaisesRegex(TypeError, "got an unexpected keyword argument <object object"):
+        errmsg = "got an unexpected keyword argument <object object"
+        with self.assertRaisesRegex(TypeError, errmsg):
             node.__replace__(**{object(): "y"})
 
 
@@ -3311,9 +3312,10 @@ class _AllFieldTypes(ast.AST):
         self.assertEqual(obj.b, [])
 
     def test_non_str_kwarg(self):
+        warn_msg = "got an unexpected keyword argument <object object"
         with (
             self.assertRaises(TypeError),
-            self.assertWarnsRegex(DeprecationWarning, "got an unexpected keyword argument <object object"),
+            self.assertWarnsRegex(DeprecationWarning, warn_msg),
         ):
             ast.Name(**{object(): 'y'})