[debbugs-tracker] bug#15320: closed ([2.0.7] Rational number representation problem)

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Your message dated Thu, 12 Sep 2013 17:03:34 -0400
with message-id <address@hidden>
and subject line Re: bug#15320: [2.0.7] Rational number representation problem
has caused the debbugs.gnu.org bug report #15320,
regarding [2.0.7] Rational number representation problem
to be marked as done.

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15320: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=15320
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--- Begin Message --- Subject: [2.0.7] Rational number representation problem Date: Tue, 10 Sep 2013 14:28:37 +0100

It seems that certain small numbers are represented as integers, as (* 4294967296 4294967296) results in 0, but (* 3294967296 3294967296) returns the correct value of 10856809481709551616. In addition, (ash 1 64) gives 0, but (ash 1 65) works correctly.

--- End Message ---

> --- Begin Message ---
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> Subject: 
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> Re: bug#15320: [2.0.7] Rational number representation problem
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> Date: 
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> Thu, 12 Sep 2013 17:03:34 -0400
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> User-agent: 
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> Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux)
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> Josh Stokes <address@hidden> writes:
>
> > It seems that certain small numbers are represented as integers, as (*
> > 4294967296 4294967296) results in 0, but (* 3294967296 3294967296)
> > returns the correct value of 10856809481709551616. In addition, (ash 1
> > 64) gives 0, but (ash 1 65) works correctly.
>
> This is fixed in Guile 2.0.9.
>
> In case you're curious: this bug came into existence when C compilers
> started optimizing out overflow checks, on the theory that if a signed
> integer overflow occurs then the behavior is unspecified and thus the
> compiler can do whatever it likes.
>
> http://stackoverflow.com/questions/14495636/strange-multiplication-behavior-in-guile-scheme-interpreter/14498437#14498437
>
>     Thanks,
>       Mark
>
>
> --- End Message ---