;; Broken version
(let-syntax
    ((foo (syntax-rules ()
            ((_)
             (letrec-syntax
                 ((bar (er-macro-transformer
                        (lambda (e r c)
                          (if (= (cadr e) 0)
                              0
                              `(,(r '+) 1 (,(r 'bar) ,(- (cadr e) 1))))))))
               (bar 5))))))
  (foo))

;; Correct version
(let-syntax
    ((foo (syntax-rules ()
            ((_)
             (letrec-syntax
                 ((bar (er-macro-transformer
                        (lambda (e r c)
                          (if (= (caddr e) 0)
                              0
                              `(,(r '+) 1 (,(cadr e) ,(cadr e)
                                           ,(- (caddr e) 1))))))))
               (bar bar 5))))))
  (foo))