Any known problems with 1.4, (read-enable 'positions) and debugging?

[Rob Browning]

I was trying to track down a problem in some code using 1.4, so I
turned on

          --with-threads \
          --enable-debug-freelist \
          --enable-debug-malloc \
          --enable-guile-debug

and I edited configure.in to add

  CFLAGS="$CFLAGS -DSCM_DEBUG_CELL_ACCESSES=1"

I also added to the code I was trying to test:

  (debug-enable 'backtrace)
  (debug-enable 'debug)
  (read-enable 'positions)

Then with this debugging 1.4, I ran in to a new failure (not the one I
was originally trying to diagnose) that looked like this

  3 segments total (2:6006, 1:46023, 1:24012)
      996 2-cells in segment 0
  3 segments total (2:6006, 1:46023, 1:24012)
      996 2-cells in segment 0
  Bad cell in freelist on newcell 321632: 0'th elt

After some experimentation, I found that if I commented out the
(read-enable 'positions) command, the newcell problem vanished.

Any idea why?  Is this a known issue, or is 'positions not likely to
be related to the problem.

Thanks

-- 
Rob Browning
rlb @defaultvalue.org, @linuxdevel.com, and @debian.org
Previously @cs.utexas.edu
GPG=1C58 8B2C FB5E 3F64 EA5C  64AE 78FE E5FE F0CB A0AD