bug#39586: pfds 0.3 hamt-fold crashes with guile-2.0 and guile-3.0

With the current pdfs (https://github.com/ijp/pfds
454033f82dac7c0b0ea9e84eed1e8ed316487c78), the code below halts on an
rnrs record assertion failure with both guile-2.2 and guile-3.0, and I'm
wondering if I'm doing something wrong, if it might be a guile bug, or
if it's more likely an issue with pfds.

  (use-modules
   ((pfds hamts) #:prefix hamts/)
   ((srfi srfi-69) #:prefix hash/))

  (define x (hamts/hamt-set
             (hamts/hamt-set
              (hamts/hamt-set
               (hamts/make-hamt hash/hash eqv?)
               #:x 1)
              #:y 2)
             #:z 3))

  (hamts/hamt-fold (lambda (k v result) result)

It looks like the crash is in (rnrs records procedural) here:

    (if (and parent (struct-ref parent rtd-index-sealed?))
	(r6rs-raise (make-assertion-violation)))

And here's the full output:

  $ GUILE_LOAD_PATH=$(pwd)/mod guile -x .sls -s hamts-error.scm
  Backtrace:
  In ice-9/boot-9.scm:
    1736:10  8 (with-exception-handler _ _ #:unwind? _ # _)
  In unknown file:
             7 (apply-smob/0 #<thunk 563a568e6b20>)
  In ice-9/boot-9.scm:
      718:2  6 (call-with-prompt _ _ #<procedure default-prompt-handle?>)
  In ice-9/eval.scm:
      619:8  5 (_ #(#(#<directory (guile-user) 563a569b6f00>)))
  In ice-9/boot-9.scm:
     2806:4  4 (save-module-excursion _)
    4351:12  3 (_)
  In pfds/private/vectors.sls:
       62:0  2 (vector-fold #<procedure 563a568470c0 at pfds/hamts.sl?> ?)
  In pfds/hamts.sls:
      308:0  1 (_ _ #t)
  In rnrs/records/procedural.scm:
      130:2  0 (_ #(#f #f #f #f #f #f #f #f #f #f #f #f #f #f #f #f # ?))

  rnrs/records/procedural.scm:130:2: ERROR:
    1. &assertion-failure

Thanks
-- 
Rob Browning
rlb @defaultvalue.org and @debian.org
GPG as of 2011-07-10 E6A9 DA3C C9FD 1FF8 C676 D2C4 C0F0 39E9 ED1B 597A
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