AssertionError: Cannot find component <model>_ManyRelatedManager for <app>.models.<model>_ManyRelatedManager

[intgr]

Bug report

What's wrong

After upgrading to django-stubs 4.2.7, one of my projects has developed an issue when used with mypy incremental mode.

It occurs when scanning some specific source file that has type errors. Running mypy the first with a clean cache successfully reports the type error. Running the second time, it fails with AssertionError. I haven't yet isolated a reproducible test case.

mypy --no-incremental is a work-around for this issue. Also reverting #1805 fixes it.

Traceback (most recent call last):
  File ".../bin/mypy", line 8, in <module>
    sys.exit(console_entry())
             ^^^^^^^^^^^^^^^
  File ".../site-packages/mypy/__main__.py", line 15, in console_entry
    main()
  File "mypy/main.py", line 99, in main
  File "mypy/main.py", line 178, in run_build
  File "mypy/build.py", line 189, in build
  File "mypy/build.py", line 263, in _build
  File "mypy/build.py", line 2941, in dispatch
  File "mypy/build.py", line 3332, in process_graph
  File "mypy/build.py", line 3413, in process_fresh_modules
  File "mypy/build.py", line 2109, in fix_cross_refs
  File "mypy/fixup.py", line 52, in fixup_module
  File "mypy/fixup.py", line 156, in visit_symbol_table
  File "mypy/fixup.py", line 72, in visit_type_info
  File "mypy/fixup.py", line 158, in visit_symbol_table
  File "mypy/nodes.py", line 1035, in accept
  File "mypy/fixup.py", line 211, in visit_var
  File "mypy/types.py", line 1429, in accept
  File "mypy/fixup.py", line 230, in visit_instance
  File "mypy/fixup.py", line 365, in lookup_fully_qualified_typeinfo
  File "mypy/lookup.py", line 49, in lookup_fully_qualified
AssertionError: Cannot find component `<model>_ManyRelatedManager` for `<app>.models.<model>_ManyRelatedManager`

How is that should be

No error. :)

System information

• python version: 3.11.6
• django version: 4.2.8
• mypy version: 1.7.0
• django-stubs version: 4.2.7
• django-stubs-ext version: 4.2.7

[flaeppe]

I'm getting a feeling it might be hard to hunt this down without a repro that allows us to inspect the cache.

[flaeppe]

The relevant lines where the <model>_ManyRelatedManager is inserted are here:

django-stubs/mypy_django_plugin/transformers/manytomany.py

Lines 193 to 197 in 7229151

	related_manager_info = helpers.add_new_class_for_module(
	module=checker.modules[related_model_instance.type.module_name],
	name=f"{related_model_instance.type.name}_ManyRelatedManager",
	bases=[many_related_manager, default_manager_node.type],
	)

[flaeppe]

Hm, I wonder if the issue seen here could be something similar to the findings in: #1872 (comment)

[intgr]

If you can't figure this out, I'll probably find time to reduce this to a reproducer by the end of the week.

[flaeppe]

Did you find any repro case in the end?