Custom Query (1030 matches)

    (defparameter *rnd-state* (make-random-state t))

    (dotimes (i 300000)
      (let* ((rand-val (random #.(1- (expt 2 64)) *rnd-state*))
             (read-val (read-from-string (with-output-to-string (o)
                                           (pprint rand-val o)))))
        (assert (= rand-val read-val)
                nil
                "rand-val: ~S, read-val: ~S" rand-val read-val)))

At some point (it may be necessary to try a few times), the assert fails and the message is:

    rand-val: 1037244565857250958, read-val: 1037244565857250958

Inspecting the variables in SLIME debuggers shows this:

#<(INTEGER 536870912) #xE65086FE5202E8E>
--------------------
Value: 1037244565857250958 = #xE65086FE5202E8E = #o71450206774510027216 = #b1110 01100101 00001000 01101111 11100101 00100000 00101110 10001110 = 1.0260616E+19
Integer-length: 64



READ-VAL:

#<(INTEGER 536870912) #xE65086FE5202E8E>
--------------------
Value: 1037244565857250958 = #xE65086FE5202E8E = #o71450206774510027216 = #b1110 01100101 00001000 01101111 11100101 00100000 00101110 10001110 = 1.0372446E+18
Integer-length: 60

I (rme) was able to duplicate this on a 32-bit ARM lisp (I haven't tested an x8632 lisp), where the message was

> Error: rand-val: 1769403817437272421, read-val: 1769403817437272421
1 > :f 0
 (76BA44C8) : 0 (%ASSERTION-FAILURE NIL (= RAND-VAL READ-VAL) "rand-val: ~S, read-val: ~S" 1769403817437272421 1769403817437272421) 452
  (SETF-PLACES-P TEST-FORM STRING &REST CONDITION-ARGS)
   SETF-PLACES-P: NIL
   TEST-FORM: (= RAND-VAL READ-VAL)
   STRING: "rand-val: ~S, read-val: ~S"
   CONDITION-ARGS: (1769403817437272421 1769403817437272421)
1 > :arg 'condition-args 0
(1769403817437272421 1769403817437272421)
1 > (mapcar 'integer-length *)
(64 61)
1 > (mapcar 'uvsize **)
(3 2)

So, that's not right: the first value appears to be a three-digit bignum.

This makes me think that we are somehow allowing non-normalized bignums to escape from the lab. I wonder if there's an error in the guts of the implementation of cl:random.

​https://lists.clozure.com/pipermail/openmcl-devel/2017-January/011456.html

? (lisp-implementation-version)
"Version 1.6-dev-r14231M  (LinuxX8632)"
? (defun foo (a b)
  (declare (type (integer -314476952 -84061465) a))
  (declare (type (integer 16008 1204497162) b))
  (logand b (the integer a)))
FOO
? (foo -299404531 1081111751)
> Error: value -299404531 is not of the expected type (UNSIGNED-BYTE 32).
> While executing: FOO, in process listener(1).

​http://clozure.com/pipermail/openmcl-devel/2012-December/013952.html