unbound variable check on R6RS is done incorrectly.

[Takashi Kato]

This should not raise an error.

(library (helper)
    (export mark)
    (import (rnrs))
(define mark #'mark)
)
(library (bug)
    (export foo)
    (import (rnrs) (for (helper) expand))

(define-syntax foo
  (lambda (x)
    (display mark) (newline)
    (syntax-case x ()
      ((_) 'ok))))
)

[Takashi Kato]

This happens only -r6 option is passed and the reported script is written in one file. So it's more like program hidden syntax's problem.

[Takashi Kato]

Executing libraries inside of 'program' syntax. (Fixes #180)

→ <<cset e0a42e967218>>