fn impl_complex_enum_tuple_variant_len(
    ctx: &Ctx,
    variant_cls_type: &Type,
    num_fields: usize,
) -> Result<(MethodAndSlotDef, ImplItemFn)>fn impl_complex_enum_tuple_variant_len(
    ctx: &Ctx,
    variant_cls_type: &Type,
    num_fields: usize,
) -> Result<(MethodAndSlotDef, ImplItemFn)>