[Haskell-cafe] MPFR / FFI - Nefarious (Simple?) bug

[Chris Mears]

"Jared Updike" <jupdike at gmail.com> writes:

> Can someone else verify if this is a Mac/BSD only problem by compiling
> and running my code? (Does the C executable"works" work? Does the
> Haskell executable "noworks" not work?) Can anyone on Linux and
> Windows attempt to compile/run and see if you can get the same
> results?

I can't help you fix the problem, but can confirm that it behaves as you
describe on my Linux system.  The program "works" produces correct
output, but noworks gives:

==================================================
[...]
290
1.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
291
1.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000315821571076304370386829039486164636536120569099678825575157477354990710405658927062619547595122867857873765133026050519075772712996650488675128428778696175272153632855303857710094714398932056909218681833163883482512398576534211955878126971368731378321605715030861892325510831739618679352919703855747262870175016933079782350322237289103929997053812694251557912158924211585973481445271933347978517620
292
[...]
384
1.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000315821571076304370386829039486164636536120569099678825575157477354990710405658927062619547595122867857873765133026050519075772712996650488675128428778696175272153632855303857710094714398932056909218681833163883482512398576534211955878126971368731378321605715030861892325510831739618679352919703855747262870175016933079782350322237289103929997053812694251557912158924211585973481445271933347978517620
385
1.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000315821571076304370386829039486164636536120569099678825575157477354990710405658927062619547595122867857873765133026050519075772712996650488675128428778696175272153632855303857710094714398932056909218681833163883482512398576534211955878126971368731378321605715030861892281684860507747503219323326708248193093246881500522519352192987169395899758472958160241015525770811984166890239749344848735134541218
386
../get_str.c:149:  assertion failed: size_s1 >= m
Aborted
==================================================

All the values from 291-384 are the same, but 385 is slightly different.