Test fail against Python 3.13-dev with a Pint error

[simonw]

I think there may be an issue with Pint - I just hit this error with Python 3.13 on my local machine:

Traceback (most recent call last):
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/bin/datasette", line 5, in <module>
    from datasette.cli import cli
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/datasette/cli.py", line 17, in <module>
    from .app import (
    ...<6 lines>...
    )
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/datasette/app.py", line 29, in <module>
    from .views.base import ureg
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/datasette/views/base.py", line 37, in <module>
    ureg = pint.UnitRegistry()
           ~~~~~~~~~~~~~~~~~^^
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/pint/facets/plain/registry.py", line 157, in __call__
    obj = super().__call__(*args, **kwargs)
          ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/pint/registry.py", line 129, in __init__
    super().__init__(
    ~~~~~~~~~~~~~~~~^
        filename=filename,
        ^^^^^^^^^^^^^^^^^^
    ...<12 lines>...
        cache_folder=cache_folder,
        ^^^^^^^^^^^^^^^^^^^^^^^^^^
    )
    ^
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/pint/facets/system/registry.py", line 57, in __init__
    super().__init__(**kwargs)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/pint/facets/group/registry.py", line 48, in __init__
    super().__init__(**kwargs)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/pint/facets/context/registry.py", line 69, in __init__
    super().__init__(**kwargs)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/pint/facets/nonmultiplicative/registry.py", line 50, in __init__
    super().__init__(**kwargs)
    ~~~~~~~~~~~~~~~~^^^^^^^^^^
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/pint/facets/plain/registry.py", line 247, in __init__
    from ... import delegates  # TODO: change thiss
    ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/pint/delegates/__init__.py", line 11, in <module>
    from . import txt_defparser
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/pint/delegates/txt_defparser/__init__.py", line 12, in <module>
    from .defparser import DefParser
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/pint/delegates/txt_defparser/defparser.py", line 10, in <module>
    from . import block, common, context, defaults, group, plain, system
  File "/Users/simon/.local/share/virtualenvs/ohno-fc4nBpYX/lib/python3.13/site-packages/pint/delegates/txt_defparser/common.py", line 21, in <module>
    @dataclass(frozen=True)
     ~~~~~~~~~^^^^^^^^^^^^^
  File "/Users/simon/.pyenv/versions/3.13-dev/lib/python3.13/dataclasses.py", line 1247, in wrap
    return _process_class(cls, init, repr, eq, order, unsafe_hash,
           ~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                          frozen, match_args, kw_only, slots,
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
                          weakref_slot)
                          ^^^^^^^^^^^^^
  File "/Users/simon/.pyenv/versions/3.13-dev/lib/python3.13/dataclasses.py", line 1015, in _process_class
    raise TypeError('cannot inherit frozen dataclass from a '
                    'non-frozen one')
TypeError: cannot inherit frozen dataclass from a non-frozen one

[simonw]

https://devguide.python.org/versions/ says that Python 3.13 is scheduled for release in October 2024.

[simonw]

Got that same Pint error in CI: https://github.com/simonw/datasette/actions/runs/8681173571/job/23803398510?pr=2321

/opt/hostedtoolcache/Python/3.13.0-alpha.6/x64/lib/python3.13/site-packages/pint/delegates/txt_defparser/common.py:21: in <module>
    @dataclass(frozen=True)
/opt/hostedtoolcache/Python/3.13.0-alpha.6/x64/lib/python3.13/dataclasses.py:1289: in wrap
    return _process_class(cls, init, repr, eq, order, unsafe_hash,
/opt/hostedtoolcache/Python/3.13.0-alpha.6/x64/lib/python3.13/dataclasses.py:1044: in _process_class
    raise TypeError('cannot inherit frozen dataclass from a '
E   TypeError: cannot inherit frozen dataclass from a non-frozen one

[simonw]

We currently pin to:

datasette/setup.py

Line 53 in 7d6d471

"pint>=0.9",

The most recent version is 0.23 from December 2023: https://github.com/hgrecco/pint/releases/tag/0.23

The only open issue I can find in Pint that relates to dataclasses is this one:

• dataclasses.FrozenInstanceError via .delegates.txt_parser.common hgrecco/pint#1766

Which links to this:

• contextlib.contextmanager raises dataclasses.FrozenInstanceError when handling a frozen dataclass exception python/cpython#99856

Unclear if either of those relate to the error I am seeing though.

[simonw]

Opened an issue against Pint here:

• Python 3.13 (dev) bug: cannot inherit frozen dataclass from a non-frozen one hgrecco/pint#1969