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Subject: |
Integer overflow on Mac OS X 64-bit |
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Date: |
Sat, 09 Nov 2013 17:39:10 +0100 |
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User-agent: |
KMail/4.11.2 (Linux/3.11.6-200.fc19.x86_64; KDE/4.11.2; x86_64; ; ) |
Hi,
I am experimenting with swig bindings for guile on Mac OS X. One of the
swig tests (the integer test) is failing. I am aware that swig is not
guile, but the bug seems to be reproducible in pure guile as well.
When I calculate (2^64) -1 on the Mac OS X platform, it returns -1. On
my fedora system, the same calculation returns
18446744073709551615
The scheme command used for this is
(display (- (expt 2 64) 1))(newline)
Note that I don't have direct access to a 64-bit Mac OS X system. I have
run into this bug via that travis CI service.
Here's a link to one of the test runs for swig on that platform:
https://travis-ci.org/gjanssens/swig/jobs/13730706
The output of the calculation as given above is on line 2161.
(The test is missing the (newline) part, so some additional output is
appended on the same line. This comes from another display command
though).
I'm not sure what additional information I can provide. If you need, I
can run more tests indirectly on the travis platform, but other than
that, my options are fairly limited.
Geert
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--- Begin Message ---
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Subject: |
Re: bug#15842: Integer overflow on Mac OS X 64-bit |
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Date: |
Thu, 14 Nov 2013 19:25:25 -0500 |
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User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) |
Geert Janssens <address@hidden> writes:
> I am experimenting with swig bindings for guile on Mac OS X. One of the
> swig tests (the integer test) is failing. I am aware that swig is not
> guile, but the bug seems to be reproducible in pure guile as well.
>
> When I calculate (2^64) -1 on the Mac OS X platform, it returns -1. On
> my fedora system, the same calculation returns
> 18446744073709551615
When reporting bugs, please tell us what version of Guile you're using.
This is fixed in Guile 2.0.9. The bug came into existence when clang
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://git.savannah.gnu.org/gitweb/?p=guile.git;a=commit;h=2355f01709eadfd5350c510cdb095b4e3f71f17c
http://stackoverflow.com/questions/14495636/strange-multiplication-behavior-in-guile-scheme-interpreter
I'm closing this bug, on the assumption that you're using an old Guile
release. Please reopen it if the problem still exists in 2.0.9.
Thanks!
Mark
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