3.14 changes annotations behaviour for dataclasses.make_dataclass

Bug report

Bug description:

I have many dataclasses created on demand by dataclasses.make_dataclass. 3.14 changes behaviour for instances of the dataclass.

In 3.13 and before, the instances have a __annotations__ attribute with the expected contents.

In 3.14, that attribute no longer exists, but calling instance.__annotate_func__ does return what was in __annotations__ before.

The 3.14 howto does say "you may access the annotations data member manually"

import dataclasses
import inspect

dc = dataclasses.make_dataclass("foo", (("one", int), ("two", str), ("three", complex)))

value = dc(1, 'hello', 3+4j)

print(f"{dir(value)=}")

try:
    print(inspect.get_annotations(value))
except Exception as exc:
    print("inspect.get_annotations exception: ", type(exc), exc)

if hasattr(dc, "__annotate_func__"):
    print(f"{value.__annotate_func__()=}")

For Python 3.13:

dir(value)=['__annotations__', '__class__', '__dataclass_fields__', '__dataclass_params__ ....

For Python 3.14:

dir(value)=['__annotate_func__', '__annotations_cache__',  '__class__', '__dataclass_fields__' ....

In both cases inspect.get_annotations() does give TypeError.

The release notes cover annotations, but nothing about changes to dataclasses instances.

Perhaps the annotations attributes shouldn't be on instances, but they have been. I also see __annotate_func__ on instances of regular objects from Python classes.

CPython versions tested on:

3.14, 3.13

Operating systems tested on:

Linux

Linked PRs

• gh-134387
• gh-134509

先从这里描述的 dataclasses.make_dataclass 和 inspect.get_annotations 行为入手，然后查看相关联的 PR gh-134387 和 gh-134509。只有在 3.14 的行为得到解决，或以与 3.13 的比较和 annotations how-to 一致的方式明确记录后，才算完成。