[Armedbear-devel] EQUALP raises type-error comparing large bignums to floats (patch attached)

[Massimiliano Ghilardi]

If a bignum exceeds the largest representable single-float,
EQUALP will raise a type-error when comparing it to a single-float.
The same problem happens with double-floats.

I am reporting this because my understanding of CLHS
http://www.lispworks.com/documentation/lw51/CLHS/Body/f_equalp.htm#equalp
tells that EQUALP is not supposed to raise errors at all:
"Exceptional Situations: None."


How to reproduce:

;; =========== double-floats ===========
(= (ash 1 1024) most-positive-double-float)
NIL

(equalp (ash 1 1024) most-positive-double-float)
; Evaluation aborted on #<TYPE-ERROR {215F90FE}>.


;; =========== single-floats ===========
(= 340282360000000000000000000000000000000 0.0f0)
NIL

(equalp 340282360000000000000000000000000000000 0.0f0)
; Evaluation aborted on #<TYPE-ERROR {1CFFC364}>.


In attachment the detailed stacktrace and a proposed patch to fix this 
problem.


Regards,

Massimiliano Ghilardi



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CL-USER> (= 340282360000000000000000000000000000000 0.0f0)
NIL

CL-USER> (equalp 340282360000000000000000000000000000000 0.0f0)
; Evaluation aborted on #<TYPE-ERROR {1CFFC364}>.

#|
The value 340282360000000000000000000000000000000 is too large to be converted to a single float.
   [Condition of type TYPE-ERROR]

Restarts:
 0: [RETRY] Retry SLIME REPL evaluation request.
 1: [*ABORT] Return to SLIME's top level.
 2: [ABORT] Abort thread.

Backtrace:
  0: (#<FUNCTION {1BEB6543}> #<TYPE-ERROR {64477E27}> #<FUNCTION {1BEB6543}>)
  1: (APPLY #<FUNCTION {1BEB6543}> (#<TYPE-ERROR {64477E27}> #<FUNCTION {1BEB6543}>))
  2: (SYSTEM::RUN-HOOK SYSTEM::*INVOKE-DEBUGGER-HOOK* #<TYPE-ERROR {64477E27}> #<FUNCTION {1BEB6543}>)
  3: (INVOKE-DEBUGGER #<TYPE-ERROR {64477E27}>)
  4: org.armedbear.lisp.Lisp.error(Lisp.java:382)
  5: org.armedbear.lisp.Bignum.floatValue(Bignum.java:292)
  6: org.armedbear.lisp.Bignum.equalp(Bignum.java:219)
  7: org.armedbear.lisp.Primitives$pf_equalp.execute(Primitives.java:405)
  8: (EQUALP 340282360000000000000000000000000000000 0.0)
  9: (SYSTEM::%EVAL (EQUALP 340282360000000000000000000000000000000 0.0))
 10: (EVAL (EQUALP 340282360000000000000000000000000000000 0.0))
 --more--
|#


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