about reportArgumentType

[jingyugao]

For err1 , I use check_int to check param is int or other. But pyrwight also report an issue . This is an false positive.
For err2, this will casue an runtime error.
Can reportArgumentType distinguish err2 from err1 ? err2 must be resolved， but err1 is not。

def get_val(i :int):
    if i >0:
        return i
    else:
        return None

def do_int(i:int):
    pass

def check_int(i:int | None):
    if i is not None:
        return True
    else:
        return False
def test(i : int):
    v=get_val(i)
    if check_int(v) :
        do_int(v) # err1: assigned int| none to int
    do_int("asd") # err2: assigned str to int

[UnboundVariable]

Your do_int function is sometimes referred to a "type guard function". The type system includes a special feature for type guard functions. You can read more about it in this chapter of the typing spec.

If you make the following change in your code, you can eliminate err1 because the type checker will now be able to apply type narrowing to the expression v.

def check_int(i: int | None) -> TypeIs[int]: ...