(🐞) FURB118 (reimplemented-operator) false positive when reference in the item position

[KotlinIsland]

b = 1
def f(a):  # Use `operator.itemgetter(b)` instead of defining a function
    return a[b]
b = 2
f([1, 2, 3])  # 3

playground
but if we follow that direction:

b = 1
f = operator.itemgetter(b)
b = 2
f([1, 2, 3])  # 2

Original issue:

class A:
    def __init__(self):
        self.foo = 1
    
    @property
    def f(self) -> object:  # Use `operator.itemgetter(self.foo)` instead of defining a function
        return self[self.foo]

playground

This function references an input in the value position, making it impossible to rewrite as an attribute

class A:
    def __init__(self):
        self.foo = 1

    f = property(operator.itemgetter(self.foo))

And if we define it in the __init__ then it would always use the intial value of foo:

class A:
    def __init__(self):
        self.foo = 1
        self.f = property(operator.itemgetter(self.foo))

[MichaReiser]

Yeah, that's certainly not safe. We should either mark the fix as unsafe or "properly" fix (although that would likely require to replace all call-sites of f which I don't think we can do easily)

[KotlinIsland]

Or detect if there is a reference in the item then don't try to fix it?

[DetachHead]

shouldn't it just not even report the error at all in that case, since it means there's no way to properly convert it to an itemgetter

[KotlinIsland]

Could be a constant