AssertionError: Should never get here in normal mode

[hamdanal]

Crash Report

The first run of mypy reports an error normally. The second run crashes with AssertionError: Should never get here in normal mode. Clearing the cache with rm -rf .mypy_cache prevents the crash in the next run but keeps crashing in the runs after.

Full reproducer below.

Traceback

$ mypy --ignore-missing-imports t/
Traceback (most recent call last):
  File "/tmp/venv/bin/mypy", line 8, in <module>
    sys.exit(console_entry())
  File "/tmp/venv/lib/python3.10/site-packages/mypy/__main__.py", line 15, in console_entry
    main()
  File "/tmp/venv/lib/python3.10/site-packages/mypy/main.py", line 95, in main
    res, messages, blockers = run_build(sources, options, fscache, t0, stdout, stderr)
  File "/tmp/venv/lib/python3.10/site-packages/mypy/main.py", line 174, in run_build
    res = build.build(sources, options, None, flush_errors, fscache, stdout, stderr)
  File "/tmp/venv/lib/python3.10/site-packages/mypy/build.py", line 194, in build
    result = _build(
  File "/tmp/venv/lib/python3.10/site-packages/mypy/build.py", line 277, in _build
    graph = dispatch(sources, manager, stdout)
  File "/tmp/venv/lib/python3.10/site-packages/mypy/build.py", line 2914, in dispatch
    process_graph(graph, manager)
  File "/tmp/venv/lib/python3.10/site-packages/mypy/build.py", line 3304, in process_graph
    process_fresh_modules(graph, prev_scc, manager)
  File "/tmp/venv/lib/python3.10/site-packages/mypy/build.py", line 3385, in process_fresh_modules
    graph[id].fix_cross_refs()
  File "/tmp/venv/lib/python3.10/site-packages/mypy/build.py", line 2120, in fix_cross_refs
    fixup_module(self.tree, self.manager.modules, self.options.use_fine_grained_cache)
  File "/tmp/venv/lib/python3.10/site-packages/mypy/fixup.py", line 53, in fixup_module
    node_fixer.visit_symbol_table(tree.names, tree.fullname)
  File "/tmp/venv/lib/python3.10/site-packages/mypy/fixup.py", line 125, in visit_symbol_table
    self.visit_type_info(value.node)
  File "/tmp/venv/lib/python3.10/site-packages/mypy/fixup.py", line 87, in visit_type_info
    info.declared_metaclass.accept(self.type_fixer)
  File "/tmp/venv/lib/python3.10/site-packages/mypy/types.py", line 1316, in accept
    return visitor.visit_instance(self)
  File "/tmp/venv/lib/python3.10/site-packages/mypy/fixup.py", line 198, in visit_instance
    inst.type = lookup_fully_qualified_typeinfo(
  File "/tmp/venv/lib/python3.10/site-packages/mypy/fixup.py", line 339, in lookup_fully_qualified_typeinfo
    assert (
AssertionError: Should never get here in normal mode, got Var:t.types.Meta instead of TypeInfo

To Reproduce

Create the following project structure:

$ tree t/
t/
├── file_with_any_type_error.py
├── __init__.py
└── types.py

0 directories, 3 files

$ cat t/__init__.py

$ cat t/types.py
from missing_module import Meta

class Foo(metaclass=Meta): ...

$ cat t/file_with_any_type_error.py
x: str
x = 1

Run mypy --ignore-missing-imports t/ more than one time without deleting the .mypy_cache folder.

Your Environment

• Mypy version used: $ mypy 1.0.0+dev.734a0b96b79f20b3290ca5fee97c749ccb2e308f (compiled: no)
• Mypy command-line flags: --ignore-missing-imports
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: Python 3.10.6 (main, Nov 2 2022, 18:53:38) [GCC 11.3.0]
• Operating system and version:
  • OS: Ubuntu 22.04.1 LTS on Windows 10 x86_64
  • Kernel: 5.15.74.2-microsoft-standard-WSL2

[hauntsaninja]

Thanks for the great issue report. Can still reproduce against latest master.