Add NamedTuple __match_args__ attribute - #15906
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AlexWaygood merged 1 commit intoJun 13, 2026
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According to mypy_primer, this change has no effect on the checked open source code. 🤖🎉 |
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srittau
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Jun 13, 2026
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LGTM, we can merge this when you undraft it.
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charliermarsh
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June 13, 2026 11:28
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Done, thanks! |
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## Summary
Python 3.10 generates `__match_args__` on named tuples so their fields
can be used in positional class patterns. We already synthesize other
generated named-tuple attributes, but did not expose `__match_args__`.
```python
from typing import NamedTuple
class Point(NamedTuple):
x: int
y: str
reveal_type(Point.__match_args__) # tuple[Literal["x"], Literal["y"]]
```
The gradual fallback for named tuples with unknown fields comes from
`NamedTupleFallback`, as proposed in
python/typeshed#15906. (I've included a
temporary copy of that typeshed change until approved.)
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Summary
Python 3.10 adds __match_args__ to classes created by NamedTuple.
This adds the class variable to _typeshed._type_checker_internals.NamedTupleFallback and the obsolete typing.NamedTuple compatibility copy.
This was found while implementing __match_args__ support for named tuples in ty: astral-sh/ruff#25934