不兼容的返回类型[7]：预期`varible [t]

发布于 2025-02-01 12:54:23 字数 650 浏览 3 评论 0原文

PYRE类型失败，因为当我们返回T时，它假设返回类型R不正确。当我们在另一类中使用派生类并访问从父类中键入的通用字段时，就会发生这种情况。

以下是在最后一行投诉的玩具代码。

T = TypeVar("T")
R = TypeVar("R")

@dataclass(frozen=True)
class A(Generic[T, R]):
    t: T
    r: R

class B(A[T, R]):
    ...

@dataclass(frozen=True)
class X(Generic[T, R]):
    a: A[T, R]
    b: B[T, R]

    def getfromA(self) -> T:
        return self.a.t

    def getfromB(self) -> T:
        # pyre-fixe[7] Incompatible return type [7]: Expected `Variable[T]` but got `Variable[R]`.Pyre
        return self.b.t

请注意，使用a，带有通用的基类时，它可以正常工作。但是，当与B（派生类）一起使用时，它会反转类型。

我是想念什么还是撞到了一些已知的pyre错误？

谢谢

原文

Pyre type fails because it assumes an incorrect return type R when we are returning T.
It happens when we use a derived class in another class and access a field that is generic typed from the parent class.

Following is the toy code for which it is complaining at the last line.

T = TypeVar("T")
R = TypeVar("R")

@dataclass(frozen=True)
class A(Generic[T, R]):
    t: T
    r: R

class B(A[T, R]):
    ...

@dataclass(frozen=True)
class X(Generic[T, R]):
    a: A[T, R]
    b: B[T, R]

    def getfromA(self) -> T:
        return self.a.t

    def getfromB(self) -> T:
        # pyre-fixe[7] Incompatible return type [7]: Expected `Variable[T]` but got `Variable[R]`.Pyre
        return self.b.t

Notice that it works correctly when using A, the base class with generic.
But when using with B, the derived class, it inverts the types.

Am I missing something or am I hitting some known pyre bug?

Thanks

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