// Field from upvar nested
    {
        let mut x = 0;
           || {
               || { //[mir]~ ERROR free region `` does not outlive
                   let y = &mut x;
                   &mut x; //[ast]~ ERROR cannot borrow `**x` as mutable more than once at a time
                   //[mir]~^ ERROR cannot borrow `x` as mutable more than once at a time
                   *y = 1;
                   drop(y);
                }
           };
    }