[ty] Fix false-positive diagnostics on super() calls (#20814)
This commit is contained in:
Alex Waygood
@@ -14,9 +14,16 @@ common usage.
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### Explicit Super Object
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<!-- snapshot-diagnostics -->
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`super(pivot_class, owner)` performs attribute lookup along the MRO, starting immediately after the
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specified pivot class.
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```toml
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[environment]
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python-version = "3.12"
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```
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```py
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class A:
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def a(self): ...
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@@ -34,21 +41,15 @@ reveal_type(C.__mro__) # revealed: tuple[<class 'C'>, <class 'B'>, <class 'A'>,
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super(C, C()).a
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super(C, C()).b
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# error: [unresolved-attribute] "Type `<super: <class 'C'>, C>` has no attribute `c`"
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super(C, C()).c
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super(C, C()).c # error: [unresolved-attribute]
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super(B, C()).a
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# error: [unresolved-attribute] "Type `<super: <class 'B'>, C>` has no attribute `b`"
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super(B, C()).b
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# error: [unresolved-attribute] "Type `<super: <class 'B'>, C>` has no attribute `c`"
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super(B, C()).c
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super(B, C()).b # error: [unresolved-attribute]
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super(B, C()).c # error: [unresolved-attribute]
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# error: [unresolved-attribute] "Type `<super: <class 'A'>, C>` has no attribute `a`"
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super(A, C()).a
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# error: [unresolved-attribute] "Type `<super: <class 'A'>, C>` has no attribute `b`"
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super(A, C()).b
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# error: [unresolved-attribute] "Type `<super: <class 'A'>, C>` has no attribute `c`"
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super(A, C()).c
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super(A, C()).a # error: [unresolved-attribute]
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super(A, C()).b # error: [unresolved-attribute]
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super(A, C()).c # error: [unresolved-attribute]
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reveal_type(super(C, C()).a) # revealed: bound method C.a() -> Unknown
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reveal_type(super(C, C()).b) # revealed: bound method C.b() -> Unknown
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@@ -56,12 +57,80 @@ reveal_type(super(C, C()).aa) # revealed: int
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reveal_type(super(C, C()).bb) # revealed: int
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```
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Examples of explicit `super()` with unusual types. We allow almost any type to be passed as the
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second argument to `super()` -- the only exceptions are "pure abstract" types such as `Callable` and
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synthesized `Protocol`s that cannot be upcast to, or interpreted as, a non-`object` nominal type.
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```py
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import types
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from typing_extensions import Callable, TypeIs, Literal, TypedDict
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def f(): ...
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class Foo[T]:
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def method(self): ...
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@property
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def some_property(self): ...
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type Alias = int
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class SomeTypedDict(TypedDict):
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x: int
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y: bytes
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# revealed: <super: <class 'object'>, FunctionType>
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reveal_type(super(object, f))
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# revealed: <super: <class 'object'>, WrapperDescriptorType>
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reveal_type(super(object, types.FunctionType.__get__))
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# revealed: <super: <class 'object'>, GenericAlias>
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reveal_type(super(object, Foo[int]))
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# revealed: <super: <class 'object'>, _SpecialForm>
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reveal_type(super(object, Literal))
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# revealed: <super: <class 'object'>, TypeAliasType>
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reveal_type(super(object, Alias))
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# revealed: <super: <class 'object'>, MethodType>
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reveal_type(super(object, Foo().method))
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# revealed: <super: <class 'object'>, property>
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reveal_type(super(object, Foo.some_property))
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def g(x: object) -> TypeIs[list[object]]:
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return isinstance(x, list)
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def _(x: object, y: SomeTypedDict, z: Callable[[int, str], bool]):
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if hasattr(x, "bar"):
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# revealed: <Protocol with members 'bar'>
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reveal_type(x)
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# error: [invalid-super-argument]
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# revealed: Unknown
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reveal_type(super(object, x))
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# error: [invalid-super-argument]
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# revealed: Unknown
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reveal_type(super(object, z))
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is_list = g(x)
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# revealed: TypeIs[list[object] @ x]
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reveal_type(is_list)
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# revealed: <super: <class 'object'>, bool>
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reveal_type(super(object, is_list))
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# revealed: <super: <class 'object'>, dict[Literal["x", "y"], int | bytes]>
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reveal_type(super(object, y))
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```
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### Implicit Super Object
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<!-- snapshot-diagnostics -->
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The implicit form `super()` is same as `super(__class__, <first argument>)`. The `__class__` refers
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to the class that contains the function where `super()` is used. The first argument refers to the
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current method’s first parameter (typically `self` or `cls`).
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```toml
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[environment]
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python-version = "3.12"
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```
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```py
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from __future__ import annotations
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@@ -74,6 +143,7 @@ class B(A):
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def __init__(self, a: int):
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# TODO: Once `Self` is supported, this should be `<super: <class 'B'>, B>`
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reveal_type(super()) # revealed: <super: <class 'B'>, Unknown>
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reveal_type(super(object, super())) # revealed: <super: <class 'object'>, super>
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super().__init__(a)
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@classmethod
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@@ -86,6 +156,123 @@ super(B, B(42)).__init__(42)
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super(B, B).f()
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```
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Some examples with unusual annotations for `self` or `cls`:
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```py
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import enum
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from typing import Any, Self, Never, Protocol, Callable
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from ty_extensions import Intersection
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class BuilderMeta(type):
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def __new__(
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cls: type[Any],
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name: str,
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bases: tuple[type, ...],
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dct: dict[str, Any],
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) -> BuilderMeta:
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# revealed: <super: <class 'BuilderMeta'>, Any>
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s = reveal_type(super())
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# revealed: Any
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return reveal_type(s.__new__(cls, name, bases, dct))
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class BuilderMeta2(type):
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def __new__(
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cls: type[BuilderMeta2],
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name: str,
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bases: tuple[type, ...],
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dct: dict[str, Any],
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) -> BuilderMeta2:
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# revealed: <super: <class 'BuilderMeta2'>, <class 'BuilderMeta2'>>
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s = reveal_type(super())
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# TODO: should be `BuilderMeta2` (needs https://github.com/astral-sh/ty/issues/501)
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# revealed: Unknown
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return reveal_type(s.__new__(cls, name, bases, dct))
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class Foo[T]:
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x: T
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def method(self: Any):
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reveal_type(super()) # revealed: <super: <class 'Foo'>, Any>
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if isinstance(self, Foo):
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reveal_type(super()) # revealed: <super: <class 'Foo'>, Any>
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def method2(self: Foo[T]):
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# revealed: <super: <class 'Foo'>, Foo[T@Foo]>
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reveal_type(super())
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def method3(self: Foo):
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# revealed: <super: <class 'Foo'>, Foo[Unknown]>
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reveal_type(super())
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def method4(self: Self):
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# revealed: <super: <class 'Foo'>, Foo[T@Foo]>
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reveal_type(super())
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def method5[S: Foo[int]](self: S, other: S) -> S:
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# revealed: <super: <class 'Foo'>, Foo[int]>
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reveal_type(super())
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return self
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def method6[S: (Foo[int], Foo[str])](self: S, other: S) -> S:
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# revealed: <super: <class 'Foo'>, Foo[int]> | <super: <class 'Foo'>, Foo[str]>
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reveal_type(super())
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return self
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def method7[S](self: S, other: S) -> S:
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# error: [invalid-super-argument]
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# revealed: Unknown
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reveal_type(super())
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return self
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def method8[S: int](self: S, other: S) -> S:
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# error: [invalid-super-argument]
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# revealed: Unknown
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reveal_type(super())
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return self
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def method9[S: (int, str)](self: S, other: S) -> S:
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# error: [invalid-super-argument]
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# revealed: Unknown
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reveal_type(super())
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return self
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def method10[S: Callable[..., str]](self: S, other: S) -> S:
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# error: [invalid-super-argument]
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# revealed: Unknown
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reveal_type(super())
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return self
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type Alias = Bar
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class Bar:
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def method(self: Alias):
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# revealed: <super: <class 'Bar'>, Bar>
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reveal_type(super())
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def pls_dont_call_me(self: Never):
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# revealed: <super: <class 'Bar'>, Unknown>
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reveal_type(super())
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def only_call_me_on_callable_subclasses(self: Intersection[Bar, Callable[..., object]]):
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# revealed: <super: <class 'Bar'>, Bar>
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reveal_type(super())
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class P(Protocol):
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def method(self: P):
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# revealed: <super: <class 'P'>, P>
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reveal_type(super())
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class E(enum.Enum):
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X = 1
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def method(self: E):
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match self:
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case E.X:
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# revealed: <super: <class 'E'>, E>
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reveal_type(super())
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```
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### Unbound Super Object
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Calling `super(cls)` without a second argument returns an _unbound super object_. This is treated as
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@@ -167,11 +354,19 @@ class A:
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## Built-ins and Literals
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```py
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from enum import Enum
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reveal_type(super(bool, True)) # revealed: <super: <class 'bool'>, bool>
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reveal_type(super(bool, bool())) # revealed: <super: <class 'bool'>, bool>
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reveal_type(super(int, bool())) # revealed: <super: <class 'int'>, bool>
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reveal_type(super(int, 3)) # revealed: <super: <class 'int'>, int>
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reveal_type(super(str, "")) # revealed: <super: <class 'str'>, str>
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reveal_type(super(bytes, b"")) # revealed: <super: <class 'bytes'>, bytes>
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class E(Enum):
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X = 42
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reveal_type(super(E, E.X)) # revealed: <super: <class 'E'>, E>
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```
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## Descriptor Behavior with Super
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@@ -342,7 +537,7 @@ def f(x: int):
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# error: [invalid-super-argument] "`typing.TypeAliasType` is not a valid class"
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super(IntAlias, 0)
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# error: [invalid-super-argument] "`Literal[""]` is not an instance or subclass of `<class 'int'>` in `super(<class 'int'>, Literal[""])` call"
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# error: [invalid-super-argument] "`str` is not an instance or subclass of `<class 'int'>` in `super(<class 'int'>, str)` call"
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# revealed: Unknown
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reveal_type(super(int, str()))
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