[ty] Patch Self for fallback-methods on NamedTuples and TypedDicts (#20328)
## Summary
We use classes like
[`_typeshed._type_checker_internals.NamedTupleFallback`](d9c76e1d9f/stdlib/_typeshed/_type_checker_internals.pyi (L54-L75))
to tack on additional attributes/methods to instances of user-defined
`NamedTuple`s (or `TypedDict`s), even though these classes are not
present in the MRO of those types.
The problem is that those classes use implicit and explicit `Self`
annotations which refer to `NamedTupleFallback` itself, instead of to
the actual type that we're adding those methods to:
```py
class NamedTupleFallback(tuple[Any, ...]):
# […]
def _replace(self, **kwargs: Any) -> typing_extensions.Self: ...
```
In effect, when we access `_replace` on an instance of a custom
`NamedTuple` instance, its `self` parameter and return type refer to the
wrong `Self`. This leads to incorrect *"Argument to bound method
`_replace` is incorrect: Argument type `Person` does not satisfy upper
bound `NamedTupleFallback` of type variable `Self`"* errors on #18007.
It would also lead to similar errors on `TypedDict`s, if they would
already implement assignability properly.
## Test Plan
I applied the following patch to typeshed and verified that no errors
appear anymore.
<details>
```diff
diff --git a/crates/ty_vendored/vendor/typeshed/stdlib/_typeshed/_type_checker_internals.pyi b/crates/ty_vendored/vendor/typeshed/stdlib/_typeshed/_type_checker_internals.pyi
index feb22aae00..8e41034f19 100644
--- a/crates/ty_vendored/vendor/typeshed/stdlib/_typeshed/_type_checker_internals.pyi
+++ b/crates/ty_vendored/vendor/typeshed/stdlib/_typeshed/_type_checker_internals.pyi
@@ -29,27 +29,27 @@ class TypedDictFallback(Mapping[str, object], metaclass=ABCMeta):
__readonly_keys__: ClassVar[frozenset[str]]
__mutable_keys__: ClassVar[frozenset[str]]
- def copy(self) -> typing_extensions.Self: ...
+ def copy(self: typing_extensions.Self) -> typing_extensions.Self: ...
# Using Never so that only calls using mypy plugin hook that specialize the signature
# can go through.
- def setdefault(self, k: Never, default: object) -> object: ...
+ def setdefault(self: typing_extensions.Self, k: Never, default: object) -> object: ...
# Mypy plugin hook for 'pop' expects that 'default' has a type variable type.
- def pop(self, k: Never, default: _T = ...) -> object: ... # pyright: ignore[reportInvalidTypeVarUse]
- def update(self, m: typing_extensions.Self, /) -> None: ...
- def __delitem__(self, k: Never) -> None: ...
- def items(self) -> dict_items[str, object]: ...
- def keys(self) -> dict_keys[str, object]: ...
- def values(self) -> dict_values[str, object]: ...
+ def pop(self: typing_extensions.Self, k: Never, default: _T = ...) -> object: ... # pyright: ignore[reportInvalidTypeVarUse]
+ def update(self: typing_extensions.Self, m: typing_extensions.Self, /) -> None: ...
+ def __delitem__(self: typing_extensions.Self, k: Never) -> None: ...
+ def items(self: typing_extensions.Self) -> dict_items[str, object]: ...
+ def keys(self: typing_extensions.Self) -> dict_keys[str, object]: ...
+ def values(self: typing_extensions.Self) -> dict_values[str, object]: ...
@overload
- def __or__(self, value: typing_extensions.Self, /) -> typing_extensions.Self: ...
+ def __or__(self: typing_extensions.Self, value: typing_extensions.Self, /) -> typing_extensions.Self: ...
@overload
- def __or__(self, value: dict[str, Any], /) -> dict[str, object]: ...
+ def __or__(self: typing_extensions.Self, value: dict[str, Any], /) -> dict[str, object]: ...
@overload
- def __ror__(self, value: typing_extensions.Self, /) -> typing_extensions.Self: ...
+ def __ror__(self: typing_extensions.Self, value: typing_extensions.Self, /) -> typing_extensions.Self: ...
@overload
- def __ror__(self, value: dict[str, Any], /) -> dict[str, object]: ...
+ def __ror__(self: typing_extensions.Self, value: dict[str, Any], /) -> dict[str, object]: ...
# supposedly incompatible definitions of __or__ and __ior__
- def __ior__(self, value: typing_extensions.Self, /) -> typing_extensions.Self: ... # type: ignore[misc]
+ def __ior__(self: typing_extensions.Self, value: typing_extensions.Self, /) -> typing_extensions.Self: ... # type: ignore[misc]
# Fallback type providing methods and attributes that appear on all `NamedTuple` types.
class NamedTupleFallback(tuple[Any, ...]):
@@ -61,18 +61,18 @@ class NamedTupleFallback(tuple[Any, ...]):
__orig_bases__: ClassVar[tuple[Any, ...]]
@overload
- def __init__(self, typename: str, fields: Iterable[tuple[str, Any]], /) -> None: ...
+ def __init__(self: typing_extensions.Self, typename: str, fields: Iterable[tuple[str, Any]], /) -> None: ...
@overload
@typing_extensions.deprecated(
"Creating a typing.NamedTuple using keyword arguments is deprecated and support will be removed in Python 3.15"
)
- def __init__(self, typename: str, fields: None = None, /, **kwargs: Any) -> None: ...
+ def __init__(self: typing_extensions.Self, typename: str, fields: None = None, /, **kwargs: Any) -> None: ...
@classmethod
def _make(cls, iterable: Iterable[Any]) -> typing_extensions.Self: ...
- def _asdict(self) -> dict[str, Any]: ...
- def _replace(self, **kwargs: Any) -> typing_extensions.Self: ...
+ def _asdict(self: typing_extensions.Self) -> dict[str, Any]: ...
+ def _replace(self: typing_extensions.Self, **kwargs: Any) -> typing_extensions.Self: ...
if sys.version_info >= (3, 13):
- def __replace__(self, **kwargs: Any) -> typing_extensions.Self: ...
+ def __replace__(self: typing_extensions.Self, **kwargs: Any) -> typing_extensions.Self: ...
# Non-default variations to accommodate couroutines, and `AwaitableGenerator` having a 4th type parameter.
_S = TypeVar("_S")
```
</details>
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