bug: TypeError: Unable to evaluate type annotation with 1.14.x

[davidmezzetti]

Hello,

First off, thank you for your efforts in open source. I've been a long time user of this library with txtai and have never had issues. So while I'm reporting an issue now, just wanted to first say I appreciate all the hard work.

With 1.14.x, I'm getting a doc build error as follows with Python 3.9.

  File "python3.9/site-packages/mkdocstrings_handlers/python/__init__.py", line 3, in <module>
    from mkdocstrings_handlers.python.handler import get_handler
  File "python3.9/site-packages/mkdocstrings_handlers/python/handler.py", line 30, in <module>
    from mkdocstrings_handlers.python.config import PythonConfig, PythonOptions
  File "python3.9/site-packages/mkdocstrings_handlers/python/config.py", line 254, in <module>
    class AutoStyleOptions:
  File "python3.9/site-packages/pydantic/dataclasses.py", line 276, in create_dataclass
    _pydantic_dataclasses.complete_dataclass(cls, config_wrapper, raise_errors=False)
  File "python3.9/site-packages/pydantic/_internal/_dataclasses.py", line 128, in complete_dataclass
    set_dataclass_fields(cls, ns_resolver, config_wrapper=config_wrapper)
  File "python3.9/site-packages/pydantic/_internal/_dataclasses.py", line 78, in set_dataclass_fields
    fields = collect_dataclass_fields(
  File "python3.9/site-packages/pydantic/_internal/_fields.py", line 322, in collect_dataclass_fields
    ann_type, _ = _typing_extra.try_eval_type(dataclass_field.type, globalns, localns)
  File "python3.9/site-packages/pydantic/_internal/_typing_extra.py", line 558, in try_eval_type
    return eval_type_backport(value, globalns, localns), True
  File "python3.9/site-packages/pydantic/_internal/_typing_extra.py", line 609, in eval_type_backport
    return _eval_type_backport(value, globalns, localns, type_params)
  File "python3.9/site-packages/pydantic/_internal/_typing_extra.py", line 641, in _eval_type_backport
    raise TypeError(
TypeError: Unable to evaluate type annotation "Annotated[str | None, Field(group='docstrings', parent='docstring_options', description='The default docstring style to use if no other style is detected.')]". If you are making use of the new typing syntax (unions using `|` since Python 3.10 or builtins subscripting since Python 3.9), you should either replace the use of new syntax with the existing `typing` constructs or install the `eval_type_backport` package.

Installing the eval_type_backport package fixes the issue. But given that it didn't happen before 1.14.x, I wanted to let you know. If this is expected, please feel free to close the issue.

[pawamoy]

Hi @davidmezzetti, thank you for the report, and for the kind words 💓 ! Could you tell me what version of Pydantic you have installed?

[davidmezzetti]

I appreciate the rapid response. Here is what I have:

pydantic==2.10.6
pydantic-settings==2.7.1
pydantic_core==2.27.2

[pawamoy]

Thank you! OK I had eval-type-backport installed locally so didn't catch this behavior. Let me add this dependency for Python 3.9 🙂 EDIT: hmm, actually no, it wouldn't be of any help to have eval-type-backport if we don't have pydantic installed in the first place. I'll instead add a check in order to deactivate Pydantic use if eval-type-backport is not available on Python 3.9.

[davidmezzetti]

Sounds good, whatever is easier for you and makes sense for the project. I appreciate the quick dialogue.

[pawamoy]

v1.14.4 released, thanks again!

[davidmezzetti]

Wow, thank you for the rapid response. Now that's service!

[davidmezzetti]

And I'll confirm the issue is fixed for my use case!

[pawamoy]

Awesome, thanks for confirming 🙏