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

Lib/inspect.py

@@ -819,7 +819,11 @@ 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 object.__spec__ is not None:
+            raise TypeError('{!r} is a built-in module'.format(object))
+        else:
+            raise TypeError('Custom module: {!r} cannot get source'
+                            .format(object))
     if isclass(object):
         if hasattr(object, '__module__'):
             module = sys.modules.get(object.__module__)

Lib/test/test_inspect/test_inspect.py

@@ -811,6 +811,13 @@ def test_getfile_builtin_module(self):
             inspect.getfile(sys)
         self.assertStartsWith(str(e.exception), '<module')
 
+    def test_getfile_custom_module(self):
+        import types
+        custom_module = types.ModuleType('custom_module')
+        with self.assertRaises(TypeError) as e:
+            inspect.getfile(custom_module)
+        self.assertStartsWith(str(e.exception), '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 @@
+the error message when when inspect getfile a custom module