AssertionError: trying to find dataclass transform spec

Bug Report
mypy crashes on the example below instead of showing an error or not showing anything.

Encountered today while refactoring a pretty big codebase. Made an accidental mistake, hence the @dataclass(frozen=True)(kw_only=True), but the way Mypy fails won't allow me to find the culprit. I couldn't find a way to debug what was causing an error (--pdb option didn't work for me).

To Reproduce

from dataclasses import dataclass


@dataclass(frozen=True)(kw_only=True)
class Foo:
    bar: str

Gist URL: https://gist.github.com/mypy-play/5b29c7aec29cbab55262d61d8c440ef3
Playground URL: https://mypy-play.net/?mypy=latest&python=3.11&gist=5b29c7aec29cbab55262d61d8c440ef3

Expected Behavior
Correctly identified error in the code, or at least no crash

Actual Behavior

mypy mypy_bug.py 
Traceback (most recent call last):
  File "/Users/misha/Dev/python-playground/.venv/bin/mypy", line 8, in <module>
    sys.exit(console_entry())
             ^^^^^^^^^^^^^^^
  File "/Users/misha/Dev/python-playground/.venv/lib/python3.11/site-packages/mypy/__main__.py", line 15, in console_entry
    main()
  File "mypy/main.py", line 94, in main
  File "mypy/main.py", line 173, in run_build
  File "mypy/build.py", line 195, in build
  File "mypy/build.py", line 268, in _build
  File "mypy/build.py", line 2927, in dispatch
  File "mypy/build.py", line 3325, in process_graph
  File "mypy/build.py", line 3420, in process_stale_scc
  File "mypy/semanal_main.py", line 99, in semantic_analysis_for_scc
  File "mypy/semanal_main.py", line 439, in apply_class_plugin_hooks
  File "mypy/semanal_main.py", line 475, in apply_hooks_to_class
  File "mypy/plugins/dataclasses.py", line 930, in dataclass_class_maker_callback
    # contains additional info beyond (and possibly including) the
  File "mypy/plugins/dataclasses.py", line 948, in _get_transform_spec
    _is_kw_only))):
AssertionError: trying to find dataclass transform spec, but reason is neither dataclasses.dataclass nor decorated with typing.dataclass_transform

Your Environment

• Mypy version used: 1.5.1 (also tried most recent from git, same)
• Mypy command-line flags: None
• Mypy configuration options from mypy.ini (and other config files): None
• Python version used: 3.11.5

Reproduisez le crash avec l’exemple de dataclass et commencez dans mypy/plugins/dataclasses.py, en particulier avec dataclass_class_maker_callback et _get_transform_spec de la trace. Vérifiez comment le @dataclass(frozen=True)(kw_only=True) malformé est traité ; c’est terminé lorsque mypy signale une erreur ou se termine sans AssertionError.