[1.1 backport] [dataclass_transform] include __dataclass_fields__ in transformed types (#14752) #14769
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…transformed types (python#14752) `dataclasses` uses a `__dataclass_fields__` attribute on each class to mark that it is a dataclass, and Typeshed checks for this attribute in its stubs for functions like `dataclasses.is_dataclass` and `dataclasses.asdict`. In python#14667, I mistakenly removed this attribute for classes transformed by a `dataclass_transform`. This was due to a misinterpretation of PEP 681 on my part; after rereading the [section on dataclass semantics](https://peps.python.org/pep-0681/#dataclass-semantics), it says: > Except where stated otherwise in this PEP, classes impacted by `dataclass_transform`, either by inheriting from a class that is decorated with `dataclass_transform` or by being decorated with a function decorated with `dataclass_transform`, are assumed to behave like stdlib dataclass. The PEP doesn't seem to state anything about `__dataclass_fields__` or the related functions as far as I can tell, so we should assume that transforms should match the behavior of `dataclasses.dataclass` in this regard and include the attribute. This also matches the behavior of Pyright, which the PEP defines as the reference implementation. (cherry picked from commit 54635de)
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According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉 |
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dataclassesuses a__dataclass_fields__attribute on each class to mark that it is a dataclass, and Typeshed checks for this attribute in its stubs for functions likedataclasses.is_dataclassanddataclasses.asdict.In #14667, I mistakenly removed this attribute for classes transformed by a
dataclass_transform. This was due to a misinterpretation of PEP 681 on my part; after rereading the section on dataclass semantics, it says:The PEP doesn't seem to state anything about
__dataclass_fields__or the related functions as far as I can tell, so we should assume that transforms should match the behavior ofdataclasses.dataclassin this regard and include the attribute. This also matches the behavior of Pyright, which the PEP defines as the reference implementation.(cherry picked from commit 54635de)