From 7a6f1a85d2973bdf7f0aa91f318dfe807046496d Mon Sep 17 00:00:00 2001
From: STerliakov <terlya.stas@gmail.com>
Date: Mon, 12 May 2025 23:16:06 +0200
Subject: [PATCH] Fall back to Incomplete if we are unable to determine the
 module name

---
 mypy/stubgenc.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mypy/stubgenc.py b/mypy/stubgenc.py
index b03a88cf6f43..b675079dd8dd 100755
--- a/mypy/stubgenc.py
+++ b/mypy/stubgenc.py
@@ -769,7 +769,11 @@ def get_type_fullname(self, typ: type) -> str:
             return "Any"
         typename = getattr(typ, "__qualname__", typ.__name__)
         module_name = self.get_obj_module(typ)
-        assert module_name is not None, typ
+        if module_name is None:
+            # This should not normally happen, but some types may resist our
+            # introspection attempts too hard. See
+            # https://github.com/python/mypy/issues/19031
+            return "_typeshed.Incomplete"
         if module_name != "builtins":
             typename = f"{module_name}.{typename}"
         return typename