test.rkt

#lang racket

(require (for-syntax syntax/stx))

(define-syntax (m1 stx)
  (syntax-case stx ()
    [(_ i1)
     (let ()
       (define i2 (car (generate-temporaries '(1))))
       #`(begin (quote-syntax #,i2)
                (define-syntax i1 (make-rename-transformer (quote-syntax #,i2)))
                (define #,i2 'dummy)
                0))]))

(define-syntax (m2 stx)
  (define expanded (local-expand (stx-car (stx-cdr stx)) 'expression null))
  (displayln (syntax->datum expanded))
  (syntax-case expanded (let-values begin quote-syntax)
    ;; match expansion on HEAD
    [(let-values () (let-values ((() (begin (quote-syntax x) _))) (let-values (((y) _)) _)))
     (displayln (free-identifier=? #'x #'y))
     #'(void)]
    ;; match expansion on 6.2
    [(let-values () (e ... ((() (begin (quote-syntax x) _)) ((y) _)) body))
     (displayln (free-identifier=? #'x #'y))
     #'(void)]))

(m2
 (let ()
   (m1 x)))