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ruff/crates/ty_python_semantic
Charlie Marsh 0793bfdb16 [ty] Avoid overload errors when detecting dataclass-on-tuple (#22687)
## Summary

Fixes some TODOs introduced in #22672 around cases like the following:


```python
from collections import namedtuple
from dataclasses import dataclass

NT = namedtuple("NT", "x y")

# error: [invalid-dataclass] "Cannot use `dataclass()` on a `NamedTuple` class"
dataclass(NT)
```

On main, `dataclass(NT)` emits `# error: [no-matching-overload]`
instead, which is wrong -- the overload does match! On main, the logic
proceeds as follows:

1. `dataclass` has two overloads:
  - `dataclass(cls: type[_T], ...) -> type[_T]`
  - `dataclass(cls: None = None, ...) -> Callable[[type[_T]], type[_T]]`
2. When `dataclass(NT)` is called:
- Arity check: Both overloads accept one positional argument, so both
pass.
- Type checking on first overload: `NT` matches `type[_T]`... but then
`invalid_dataclass_target()` runs and adds `InvalidDataclassApplication`
error
- Type checking on second overload: `NT` doesn't match `None`, so we
have a type error.
3. After type checking, both overloads have errors.
4. `matching_overload_index()` filters by
`overload.as_result().is_ok()`, which checks if `errors.is_empty()`.
Since both overloads have errors, neither matches...
5. We emit the "No overload matches arguments" error.

Instead, we now differentiate between non-matching errors, and errors
that occur when we _do_ match, but the call has some other semantic
failure.
2026-01-19 13:55:11 +00:00
..
2025-05-03 19:49:15 +02:00