def _(flag: bool):
    class A:
        always_bound: int = 1

        if flag:
            union = 1
        else:
            union = "abc"

        if flag:
            union_declared: int = 1
        else:
            union_declared: str = "abc"

        if flag:
            possibly_unbound: str = "abc"

    reveal_type(A.always_bound)  # revealed: int

    reveal_type(A.union)  # revealed: int | str

    reveal_type(A.union_declared)  # revealed: int | str

    # error: [possibly-missing-attribute] "Attribute `possibly_unbound` may be missing on class `A`"
    reveal_type(A.possibly_unbound)  # revealed: str

    # error: [unresolved-attribute] "Class `A` has no attribute `non_existent`"
    reveal_type(A.non_existent)  # revealed: Unknown

class IntBox:
    attr: int

class StrBox:
    attr: str

def f() -> None:
    (box := IntBox()).attr = 1
    box = StrBox()
    reveal_type(box.attr)  # revealed: str