[Openmcl-devel] = fails for integers with the same printed representation on 32bit CCL

[R. Matthew Emerson]

Filed as http://trac.clozure.com/ccl/ticket/1403

I don't think = is the problem.  It seems more likely to me that cl:random is returning a bignum with too many bignum digits.

Thanks for the report.


> On Jan 8, 2017, at 7:51 PM, Anton Vodonosov <avodonosov at gmail.com> wrote:
> 
> Hello,
> 
> I reduced the use case to the following
> 
>     (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)))
> 
> 
>    ;; it doesn't fail from the first time, try 2-3 times more
> 
> At some point assert fails and the message is:
> 
>     rand-val: 1037244565857250958, read-val: 1037244565857250958
>        [Condition of type SIMPLE-ERROR]
> 
> Inspecting the variables in SLIME debuggers shows this:
> 
> 
> RAND-VAL:
> 
> #<(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
> 
> 
> As you see, it prints the same binary representation, but Integer-length: 64 vs Integer-length: 60
> 
> 
> Is it a CCL bug?