gh-125519: Improve traceback if `importlib.reload()` is called with a non-module object (#125520)

Lib/importlib/__init__.py

@@ -103,7 +103,7 @@ def reload(module):
         try:
             name = module.__name__
         except AttributeError:
-            raise TypeError("reload() argument must be a module")
+            raise TypeError("reload() argument must be a module") from None
 
     if sys.modules.get(name) is not module:
         raise ImportError(f"module {name} not in sys.modules", name=name)

Lib/test/test_importlib/test_api.py

@@ -9,6 +9,7 @@ import sys
 from test import support
 from test.support import import_helper
 from test.support import os_helper
+import traceback
 import types
 import unittest
 
@@ -354,6 +355,20 @@ class ReloadTests:
             with self.assertRaises(ModuleNotFoundError):
                 self.init.reload(module)
 
+    def test_reload_traceback_with_non_str(self):
+        # gh-125519
+        with support.captured_stdout() as stdout:
+            try:
+                self.init.reload("typing")
+            except TypeError as exc:
+                traceback.print_exception(exc, file=stdout)
+            else:
+                self.fail("Expected TypeError to be raised")
+        printed_traceback = stdout.getvalue()
+        self.assertIn("TypeError", printed_traceback)
+        self.assertNotIn("AttributeError", printed_traceback)
+        self.assertNotIn("module.__spec__.name", printed_traceback)
+
 
 (Frozen_ReloadTests,
  Source_ReloadTests

Misc/NEWS.d/next/Library/2024-10-15-14-01-03.gh-issue-125519.TqGh6a.rst

@@ -0,0 +1,2 @@
+Improve traceback if :func:`importlib.reload` is called with an object that
+is not a module. Patch by Alex Waygood.