memory corruption on racketcs with reencode-output-port

[samth]

This program:

#lang racket/base
(require scheme/port)
(define-struct transcoder (codec eol-style error-handling-mode))
(define-struct codec (enc))
(define utf-8 (make-codec "utf-8"))
(define-struct textual-output-port (port transcoder)
  #:property prop:output-port 0)

(define utf8-transcoder
  (make-transcoder utf-8 'none '?))
(define (transcode-output p t)
  (reencode-output-port p
                        (codec-enc (transcoder-codec t))
                        #f
                        #t
                        (object-name p)
                        #f
                        #f))

(let-values (((out) (make-textual-output-port (transcode-output (open-output-string) utf8-transcoder) utf8-transcoder)))
  (let-values
             (((r) (begin (newline out) #;(get-output-string out))))
  #t))

causes an "invalid memory reference" error on racketcs, but works correctly on racket.

[samth]

Originally reported in #2675.

[gus-massa]

Minimized version:

#lang racket/base
(define-struct myport (port)
  #:property prop:output-port 0)

(define out
  (make-myport
   #;(current-output-port)
   (open-output-string)))
#;(display 777 out)
(newline out)

You can replace (open-output-string) with (open-output-string), but you can't replace newline with display. My guess is that newline doesn't understand custom ports.

[mflatt]

Thanks for the report and for narrowing down the problem!

For future reference, when you suspect a bug in the Racket layer over Chez Scheme, it can help to try building that layer in safe mode. To do that, comment out --unsafe in racket/src/cs/Makefile, then go to racket/src/build/cs/c (or wherever your build directory is) and delete all ".so" files, make, and try ./racketcs.

Safe mode produces an error that confirms @gus-massa's suspicion: core-port-buffer: #<myport> is not of type #<struct-type>.

[gus-massa]

Now the test of racket-r7rs finish cleanly in HEAD and HEADCS https://travis-ci.org/gus-massa/racket-r7rs/builds/542031427