gh-138542: error message is wrong when inspect a custom module

Lib/inspect.py

@@ -819,7 +819,9 @@ def getfile(object):
     if ismodule(object):
         if getattr(object, '__file__', None):
             return object.__file__
-        raise TypeError('{!r} is a built-in module'.format(object))
+        if getattr(object, '__spec__', None) is not None:
+            raise TypeError(f'{object!r} is a built-in module')
+        raise TypeError(f'Cannot get source from {object!r}')
     if isclass(object):
         if hasattr(object, '__module__'):
             module = sys.modules.get(object.__module__)

Lib/test/test_inspect/test_inspect.py

@@ -811,6 +811,15 @@ def test_getfile_builtin_module(self):
             inspect.getfile(sys)
         self.assertStartsWith(str(e.exception), '<module')
 
+    def test_getfile_custom_module(self):
+        import re
+        custom_module = types.ModuleType('custom_module')
+        msg = re.escape(
+             f'Cannot get source from {custom_module!r}'
+        )
+        with self.assertRaisesRegex(TypeError, msg) as e:
+            inspect.getfile(custom_module)
+
     def test_getfile_builtin_class(self):
         with self.assertRaises(TypeError) as e:
             inspect.getfile(int)

Misc/NEWS.d/next/Library/2025-09-05-23-18-51.gh-issue-138542.hQ9Q04.rst

@@ -0,0 +1 @@
+Fix :func:`inspect.getfile` error message for custom module objects.