Function privilege_allowed 

pub fn privilege_allowed(
    owner: &RoleIdentity,
    acl: Option<&[ObjectAclEntry]>,
    grant_option: bool,
    superuser: bool,
    has_role: impl Fn(&RoleIdentity) -> bool,
) -> bool

Whether a role holding has_role memberships may use the object, or grant it when grant_option is set.