Crash on namedtuple + @dataclass

[ericbuehl]

Crash Report

running under python 3.13.1 results in the following crash when it does not crash under 3.12.8

Traceback

Traceback (most recent call last):
  File "<redacted>/.venv/bin/mypy", line 8, in <module>
    sys.exit(console_entry())
             ~~~~~~~~~~~~~^^
  File "<redacted>/.venv/lib/python3.13/site-packages/mypy/__main__.py", line 15, in console_entry
    main()
    ~~~~^^
  File "mypy/main.py", line 109, in main
  File "mypy/main.py", line 193, in run_build
  File "mypy/build.py", line 194, in build
  File "mypy/build.py", line 269, in _build
  File "mypy/build.py", line 2940, in dispatch
  File "mypy/build.py", line 3338, in process_graph
  File "mypy/build.py", line 3433, in process_stale_scc
  File "mypy/semanal_main.py", line 99, in semantic_analysis_for_scc
  File "mypy/semanal_main.py", line 443, in apply_class_plugin_hooks
  File "mypy/semanal_main.py", line 479, in apply_hooks_to_class
  File "mypy/plugins/dataclasses.py", line 966, in dataclass_class_maker_callback
  File "mypy/plugins/dataclasses.py", line 389, in transform
  File "mypy/plugins/dataclasses.py", line 409, in _add_dunder_replace
  File "mypy/plugins/common.py", line 238, in add_method_to_class
  File "mypy/plugins/common.py", line 315, in _prepare_class_namespace
ValueError: list.remove(x): x not in list

To Reproduce

mypy <source dir>

Your Environment

This error occurs on a large proprietary code base. I have removed all custom configuration options and plugins normally specified in pyproject.toml, cleaned .mypy_cache dir and reproduced the error with a vanilla mypy invocation. No crash when using python 3.12.8, but traceback above occurs when switching to python 3.13.1

• Mypy version used: 1.14.1
• Mypy command-line flags: none
• Mypy configuration options from mypy.ini (and other config files): none
• Python version used: tested successfully under python 3.12.8, fails under 3.13.1
• Operating system and version: OS X Sequoia

[cdce8p]

Thanks for the report @ericbuehl! Are you able to narrow the crash down to a particular file, ideally an example you can post here? Without it, this would be quite difficult to resolve.

For what it's worth, I know at least one large project which is also already running on 3.13.1 and hasn't encountered the crash yet.

[ericbuehl]

@cdce8p I was able to narrow the crash down to a concise repro:

from dataclasses import dataclass
from typing import NamedTuple

@dataclass
class Imageable(NamedTuple):
    id: int

I'm not sure of the practical need for this dataclass+namedtuple but alas mypy probably shouldn't crash nonetheless

[tyralla]

from dataclasses import dataclass
from typing import NamedTuple

@dataclass
class Imageable(NamedTuple):
    id: int

Imageable(1)  # AttributeError: can't set attribute  (Python)

It seems that dataclass and NamedTuple are not really compatible, so besides not crashing Mypy reporting a warning would be nice.