mypy crashes on a dataclass

Crash Report

Traceback

Traceback (most recent call last):
  File "/home/dnpetrov/Work/memory_tests/venv/bin/mypy", line 8, in <module>
    sys.exit(console_entry())
             ^^^^^^^^^^^^^^^
  File "/home/dnpetrov/Work/memory_tests/venv/lib/python3.12/site-packages/mypy/__main__.py", line 15, in console_entry
    main()
  File "mypy/main.py", line 103, in main
  File "mypy/main.py", line 187, in run_build
  File "mypy/build.py", line 193, in build
  File "mypy/build.py", line 268, in _build
  File "mypy/build.py", line 2950, in dispatch
  File "mypy/build.py", line 3348, in process_graph
  File "mypy/build.py", line 3443, in process_stale_scc
  File "mypy/semanal_main.py", line 99, in semantic_analysis_for_scc
  File "mypy/semanal_main.py", line 432, in apply_class_plugin_hooks
AssertionError: Internal error: too many class plugin hook passes

To Reproduce

Following code crashes mypy:

from dataclasses import dataclass

def fn(a: int) -> int:
    return a

@dataclass
class Test:
    foo = fn
    foo: int = 42

While the code itself, indeed, looks very strange, mypy should not crash, or at least should provide some meaningful diagnostic instead of "Internal error: too many class plugin hook passes".

Your Environment

$ mypy --version
mypy 1.11.2 (compiled: yes)
$ python --version
Python 3.12.3

Also reproduces on the latest and greatest master branch (30b2a2d99a05c5176eff449b80abb61eae5f2043).

Riproduci il crash con l’esempio di dataclass, quindi esamina mypy/semanal_main.py in corrispondenza di apply_class_plugin_hooks e l’elaborazione correlata in mypy/build.py. Traccia il motivo per cui viene raggiunto il limite di passaggi degli hook dei plugin di classe; il lavoro è completato quando questo input non va più in crash e produce invece una diagnosi significativa oppure termina correttamente.