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From: Konrad Hinsen <konrad.hinsen@fastmail.net>
To: "Bonface M. K." <bonfacemunyoki@gmail.com>
Cc: guix-devel@gnu.org, "Ludovic Courtès" <ludovic.courtes@inria.fr>,
	"simon tournier" <simon.tournier@univ-paris-diderot.fr>,
	guix-hpc@gnu.org
Subject: Re: Reproducible Research Hackathon: Friday, July 3rd
Date: Tue, 14 Jul 2020 21:53:56 +0200	[thread overview]
Message-ID: <m1o8ohna97.fsf@fastmail.net> (raw)
In-Reply-To: <86tuyaeasw.fsf@gmail.com>

Hi Bonface and Ludo,

> That's strange. To get the right results, you'd have to do a `2L ** 64`.

Exactly. The long integer arithmetic works fine, it's the detection
of the overflow of 64-bit ints that fails.

> When I tried `2 ** 63` I got `-9223372036854775808`. There's also an

Good catch, I hadn't tried that one!

> Oooh, thank you!  It looks like an “interesting” bug, one of those
> that can help make the case for precise software environment control.
> :-)

Exactly. Most people have understood by now that Python and libraries
higher up on the stack suffer from breaking changes, but C and
libc/libm, that's still the unshakable ground on which software can
safely be built.

> Uh, weird!  We could check whether building Python with ‘-fwrapv’ helps.
> See also <https://lwn.net/Articles/511259/>.

Interesting. I am finding out that I don't know most of the possible
suspects in this crime story ;-)

Cheers,
  Konrad


  reply	other threads:[~2020-07-14 19:54 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-30 12:40 Reproducible Research Hackathon: Friday, July 3rd simon tournier
2020-07-01  4:57 ` Pjotr Prins
2020-07-01  9:10   ` zimoun
2020-07-01  9:21     ` Efraim Flashner
2020-07-03 17:10 ` zimoun
2020-07-03 17:36   ` Ricardo Wurmus
2020-07-03 17:56   ` Paul Garlick
2020-07-03 18:19     ` zimoun
2020-07-07 17:52       ` Paul Garlick
2020-07-03 21:17     ` Ricardo Wurmus
2020-07-07 17:44       ` Paul Garlick
2020-07-04  9:51   ` Konrad Hinsen
2020-07-13 13:41     ` Ludovic Courtès
2020-07-14  8:13       ` Konrad Hinsen
2020-07-14  8:54         ` Bonface M. K.
2020-07-14 19:53           ` Konrad Hinsen [this message]
2020-07-14 13:18         ` Ludovic Courtès

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