From b800d6d92af54dd05db71cd7261408941bab5d00 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?tonghuaroot=20=28=E7=AB=A5=E8=AF=9D=29?=
 <tonghuaroot@gmail.com>
Date: Tue, 13 Oct 2026 07:37:58 +0800
Subject: [PATCH] gh-152692: Fix annotationlib.type_repr() for bound built-in
 methods (GH-152693)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

type_repr() returned a string naming a nonexistent module None -- e.g.
type_repr([].append) == 'None.list.append' -- for bound built-in methods,
whose __module__ is None.

Return the qualified name when __module__ is None, as already done for the
"builtins" module.
(cherry picked from commit 6979003a1d73383ce798eb1301fe93d4d74b1903)

Co-authored-by: tonghuaroot (童话) <tonghuaroot@gmail.com>
---
 Lib/annotationlib.py                                 | 12 ++++++++++--
 Lib/test/test_annotationlib.py                       | 12 ++++++++++++
 .../2026-06-30-15-00-00.gh-issue-152692.tr3pr0.rst   |  4 ++++
 3 files changed, 26 insertions(+), 2 deletions(-)
 create mode 100644 Misc/NEWS.d/next/Library/2026-06-30-15-00-00.gh-issue-152692.tr3pr0.rst

diff --git a/Lib/annotationlib.py b/Lib/annotationlib.py
index 5c9a0812646f814..c2b6470b26284ff 100644
--- a/Lib/annotationlib.py
+++ b/Lib/annotationlib.py
@@ -1113,9 +1113,17 @@ def type_repr(value):
 
     """
     if isinstance(value, (type, types.FunctionType, types.BuiltinFunctionType)):
-        if value.__module__ == "builtins":
+        module = value.__module__
+        if module is None:
+            # Built-in methods have __module__ set to None; recover the module
+            # from the bound object (the class itself for class-bound methods).
+            obj = getattr(value, "__self__", None)
+            if obj is not None:
+                cls = obj if isinstance(obj, type) else type(obj)
+                module = cls.__module__
+        if module is None or module == "builtins":
             return value.__qualname__
-        return f"{value.__module__}.{value.__qualname__}"
+        return f"{module}.{value.__qualname__}"
     elif isinstance(value, _Template):
         tree = _template_to_ast(value)
         return ast.unparse(tree)
diff --git a/Lib/test/test_annotationlib.py b/Lib/test/test_annotationlib.py
index 7db6f8745ac84ff..f5b226f3e205c4f 100644
--- a/Lib/test/test_annotationlib.py
+++ b/Lib/test/test_annotationlib.py
@@ -1857,6 +1857,18 @@ def nested():
             type_repr(nested), f"{__name__}.TestTypeRepr.test_type_repr.<locals>.nested"
         )
         self.assertEqual(type_repr(len), "len")
+        # gh-152692: built-in methods have __module__ set to None
+        self.assertEqual(type_repr([].append), "list.append")
+        self.assertEqual(type_repr((1).bit_length), "int.bit_length")
+        self.assertEqual(type_repr(dict.fromkeys), "dict.fromkeys")
+        # Methods of extension types also have __module__ set to None, but
+        # are not in the builtins module.
+        import datetime
+        self.assertEqual(
+            type_repr(datetime.datetime(2000, 1, 1).isoformat),
+            "datetime.datetime.isoformat",
+        )
+        self.assertEqual(type_repr(datetime.date.today), "datetime.date.today")
         self.assertEqual(type_repr(type_repr), "annotationlib.type_repr")
         self.assertEqual(type_repr(times_three), f"{__name__}.times_three")
         self.assertEqual(type_repr(...), "...")
diff --git a/Misc/NEWS.d/next/Library/2026-06-30-15-00-00.gh-issue-152692.tr3pr0.rst b/Misc/NEWS.d/next/Library/2026-06-30-15-00-00.gh-issue-152692.tr3pr0.rst
new file mode 100644
index 000000000000000..d92011f2c5acd7d
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2026-06-30-15-00-00.gh-issue-152692.tr3pr0.rst
@@ -0,0 +1,4 @@
+Fix :func:`annotationlib.type_repr` returning a string such as
+``None.list.append`` for bound built-in methods, whose ``__module__`` is
+``None``.  It now returns the qualified name, as it already did for other
+builtins.