gistfile1.txt

struct Foo {}

let foo: Foo;
let a: &'a mut &'aa mut Foo;
let b: &'b mut &'bb mut Foo;
let c: &'c mut &'cc mut Foo;

block START {
    goto X;
}

block X {
    b = &'b mut *a;
    goto END;
}

block END {
    *a = &'foo mut foo;
    use(b);
}

assert X/1 in 'b;
assert b live at END;