From ce3ac5545e8c9deb019aee3effd910b77c91c29d Mon Sep 17 00:00:00 2001
From: Thomas Wouters <thomas@python.org>
Date: Fri, 17 Jan 2025 17:45:55 +0100
Subject: [PATCH] Fix pydoc's docclass() for classes inheriting from object
 without the `__module__` attribute, like `_testcapi.HeapType`.

---
 Lib/pydoc.py                      | 3 ++-
 Lib/test/test_pydoc/test_pydoc.py | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/Lib/pydoc.py b/Lib/pydoc.py
index 9e84292aaf825f..922946e5fa7ddb 100644
--- a/Lib/pydoc.py
+++ b/Lib/pydoc.py
@@ -1435,7 +1435,8 @@ def makename(c, m=object.__module__):
         # List the built-in subclasses, if any:
         subclasses = sorted(
             (str(cls.__name__) for cls in type.__subclasses__(object)
-             if not cls.__name__.startswith("_") and cls.__module__ == "builtins"),
+             if (not cls.__name__.startswith("_") and
+                 getattr(cls, '__module__', '') == "builtins")),
             key=str.lower
         )
         no_of_subclasses = len(subclasses)
diff --git a/Lib/test/test_pydoc/test_pydoc.py b/Lib/test/test_pydoc/test_pydoc.py
index cec18aa9440c9e..b02ba3aafd4d20 100644
--- a/Lib/test/test_pydoc/test_pydoc.py
+++ b/Lib/test/test_pydoc/test_pydoc.py
@@ -556,6 +556,14 @@ class object
          |      ... and 82 other subclasses
         """
         doc = pydoc.TextDoc()
+        try:
+            # Make sure HeapType, which has no __module__ attribute, is one
+            # of the known subclasses of object. (doc.docclass() used to
+            # fail if HeapType was imported before running this test, like
+            # when running tests sequentially.)
+            from _testcapi import HeapType
+        except ImportError:
+            pass
         text = doc.docclass(object)
         snip = (" |  Built-in subclasses:\n"
                 " |      async_generator\n"